below find all my code and xml. My problem is that the spinner (in code spinner1) is null for some reason I can't determine and I get no errors other than the app failing to run. Any help would be appreciated!
activity_main.xml:
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/black"
tools:context=".MainActivity" />
MainActivity.java:
package com.example.passwordplayground;
import java.util.Locale;
import com.example.MyApplication.EncryptionSpinner;
import com.example.MyApplication.MyApplication;
import android.app.ActionBar;
import android.app.Activity;
import android.app.FragmentTransaction;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.NavUtils;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
/**
* The {#link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {#link android.support.v4.app.FragmentPagerAdapter} derivative, which
* will keep every loaded fragment in memory. If this becomes too memory
* intensive, it may be best to switch to a
* {#link android.support.v4.app.FragmentStatePagerAdapter}.
*/
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {#link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Set up the action bar.
final ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
Spinner spinner1 = (Spinner) findViewById(R.id.encryptionSpin);
if (spinner1 == null)
System.out.println("Spinner1 is null");
else
System.out.println("Funcion is null");
spinner1.setOnItemSelectedListener(new EncryptionSpinner());
// Create the adapter that will return a fragment for each of the three
// primary sections of the app.
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
// When swiping between different sections, select the corresponding
// tab. We can also use ActionBar.Tab#select() to do this if we have
// a reference to the Tab.
mViewPager
.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
// Create a tab with text corresponding to the page title defined by
// the adapter. Also specify this Activity object, which implements
// the TabListener interface, as the callback (listener) for when
// this tab is selected.
actionBar.addTab(actionBar.newTab()
.setText(mSectionsPagerAdapter.getPageTitle(i))
.setTabListener(this));
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public void onTabSelected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
// When the given tab is selected, switch to the corresponding page in
// the ViewPager.
mViewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
#Override
public void onTabReselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a DummySectionFragment (defined as a static inner class
// below) with the page number as its lone argument.
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
fragment.setArguments(args);
return fragment;
}
#Override
public int getCount() {
// Show 4 total pages.
return 4;
}
#Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return getString(R.string.title_section1).toUpperCase(l);
case 1:
return getString(R.string.title_section2).toUpperCase(l);
case 2:
return getString(R.string.title_section3).toUpperCase(l);
case 3:
return ("Practicality").toUpperCase();
}
return null;
}
}
/**
* A dummy fragment representing a section of the app, but that simply
* displays dummy text.
*/
public static class DummySectionFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
public static final String ARG_SECTION_NUMBER = "section_number";
public DummySectionFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = null;
if (getArguments().getInt(ARG_SECTION_NUMBER)==1) {
rootView = inflater.inflate(R.layout.encryption,container, false);
}
else if (getArguments().getInt(ARG_SECTION_NUMBER)==2) {
rootView = inflater.inflate(R.layout.fragment_main_dummy,
container, false);
TextView dummyTextView = (TextView) rootView
.findViewById(R.id.section_label);
dummyTextView.setText("I'm second!");
}
else if (getArguments().getInt(ARG_SECTION_NUMBER)==3) {
//dummyTextView.setText("I'm third");
}
else if (getArguments().getInt(ARG_SECTION_NUMBER)==4) {
//dummyTextView.setText("I'm fourth and last!");
}
return rootView;
}
}
}
encryption.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:android1="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity$Encryption" >
<Spinner
android1:id="#+id/encryptionSpin"
android1:layout_width="fill_parent"
android1:layout_height="wrap_content"
android1:layout_alignParentTop="true"
android1:layout_centerHorizontal="true"
android1:layout_marginTop="14dp"
android1:background="#color/orange"
android1:entries="#array/cryptArray" />
</RelativeLayout>
EncryptionSpinner.java:
package com.example.MyApplication;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener;
public class EncryptionSpinner implements OnItemSelectedListener {
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
// An item was selected. You can retrieve the selected item using
// parent.getItemAtPosition(pos)
Toast toast = Toast.makeText(MyApplication.getAppContext(), parent.getItemAtPosition(pos).toString(), Toast.LENGTH_LONG);
toast.show();
System.out.println(parent.getItemAtPosition(pos).toString());
}
public void onNothingSelected(AdapterView<?> parent) {
// Another interface callback
}
}
Logcat Error:
04-09 01:16:28.637: I/System.out(1440): Spinner1 is null
04-09 01:16:28.657: D/AndroidRuntime(1440): Shutting down VM
04-09 01:16:28.657: W/dalvikvm(1440): threadid=1: thread exiting with uncaught exception (group=0x414c4700)
04-09 01:16:28.692: E/AndroidRuntime(1440): FATAL EXCEPTION: main
04-09 01:16:28.692: E/AndroidRuntime(1440): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.passwordplayground/com.example.passwordplayground.MainActivity}: java.lang.NullPointerException
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.app.ActivityThread.access$600(ActivityThread.java:141)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.os.Handler.dispatchMessage(Handler.java:99)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.os.Looper.loop(Looper.java:137)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.app.ActivityThread.main(ActivityThread.java:5103)
04-09 01:16:28.692: E/AndroidRuntime(1440): at java.lang.reflect.Method.invokeNative(Native Method)
04-09 01:16:28.692: E/AndroidRuntime(1440): at java.lang.reflect.Method.invoke(Method.java:525)
04-09 01:16:28.692: E/AndroidRuntime(1440): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
04-09 01:16:28.692: E/AndroidRuntime(1440): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
04-09 01:16:28.692: E/AndroidRuntime(1440): at dalvik.system.NativeStart.main(Native Method)
04-09 01:16:28.692: E/AndroidRuntime(1440): Caused by: java.lang.NullPointerException
04-09 01:16:28.692: E/AndroidRuntime(1440): at com.example.passwordplayground.MainActivity.onCreate(MainActivity.java:65)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.app.Activity.performCreate(Activity.java:5133)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-09 01:16:28.692: E/AndroidRuntime(1440): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
04-09 01:16:28.692: E/AndroidRuntime(1440): ... 11 more
Layouts' Gui:
if you want to user spinner from activity_main then you have to put it in that file because right now its not their and it is in encryption.xml file.
make activity_main.xml like below:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:android1="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity$Encryption" >
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/black"
tools:context=".MainActivity" />
<Spinner
android1:id="#+id/encryptionSpin"
android1:layout_width="fill_parent"
android1:layout_height="wrap_content"
android1:layout_alignParentTop="true"
android1:layout_centerHorizontal="true"
android1:layout_marginTop="14dp"
android1:background="#color/orange"
android1:entries="#array/cryptArray" />
</RelativeLayout>
You have inflated the layout activity_main in your activity and you are trying to access the Spinner which is not in your activity_main layout.
In that point you are getting error. As the Spinner does not resides in your activity_main layout.
So will have to initialize your Spinner in DummySectionFragment onCreateView method as below:
public static class DummySectionFragment extends Fragment {
public static final String ARG_SECTION_NUMBER = "section_number";
public DummySectionFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = null;
if (getArguments().getInt(ARG_SECTION_NUMBER)==1) {
rootView = inflater.inflate(R.layout.encryption,container, false);
Spinner spinner1 = (Spinner)rootView.findViewById(R.id.encryptionSpin);
}
you see there is null pointer exception.
means you have no control on the components you are using.
this could be caused due to two reason
1. two components have same ids.
2. wrong defined layout.
in your case you are using layout
R.layout.activity_main
while your layout name is
R.layout.encryption
change the name of layout and you are ready to go.
You putting ViewPager in activity_mail layout and Spinner in encryption.xml if u setting content view as any one of xml. so any one ll identify another one will not be identify. It will throw the null pointer exception.
R.layout.activity_main having ViewPager
R.layout.encryption having Spinner
if u set setcontentView(R.layout.activity_main) then findViewById(R.id.encryptionSpin); line will throw null pointer.
if u set setcontentView(R.layout.encryption) then mViewPager = (ViewPager) findViewById(R.id.pager); line will throw null pointer.
Related
I am trying to call a fragment that acts as a side bar menu but when I try to run my app it says application has stopped. I have been trying all the ways I found on the internet. This is what I made so far.
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.user.sample.MainActivity">
<TextView
android:onClick="menuHeader"
android:layout_width="match_parent"
android:layout_height="40dp"
android:text="☰"
android:layout_alignParentTop="true"
android:background="#931d21"
android:gravity="center_vertical"
android:paddingLeft="10dp" />
<fragment
android:name="com.example.user.sample.MenuFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/fragment_container" />
</LinearLayout
MainActivity.java
package com.example.user.sample;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
public class MainActivity extends FragmentActivity {
private MenuFragment fragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void menuHeader(View view) {
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragment = new MenuFragment();
fragmentTransaction.add(R.id.fragment_container, fragment);
fragmentTransaction.commit();
}
}
MenuFragment.java
package com.example.user.sample;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* A fragment representing a list of Items.
* <p/>
* Activities containing this fragment MUST implement the {#link OnListFragmentInteractionListener}
* interface.
*/
public class MenuFragment extends Fragment {
// TODO: Customize parameter argument names
private static final String ARG_COLUMN_COUNT = "column-count";
// TODO: Customize parameters
private int mColumnCount = 1;
private OnListFragmentInteractionListener mListener;
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public MenuFragment() {
}
// TODO: Customize parameter initialization
#SuppressWarnings("unused")
public static MenuFragment newInstance(int columnCount) {
MenuFragment fragment = new MenuFragment();
Bundle args = new Bundle();
args.putInt(ARG_COLUMN_COUNT, columnCount);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_menu_list, container, false);
// Set the adapter
if (view instanceof RecyclerView) {
Context context = view.getContext();
RecyclerView recyclerView = (RecyclerView) view;
if (mColumnCount <= 1) {
recyclerView.setLayoutManager(new LinearLayoutManager(context));
} else {
recyclerView.setLayoutManager(new GridLayoutManager(context, mColumnCount));
}
}
return view;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnListFragmentInteractionListener) {
mListener = (OnListFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnListFragmentInteractionListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnListFragmentInteractionListener {
// TODO: Update argument type and name
// void onListFragmentInteraction(DummyItem item);
}
}
LOGCAT
02-10 10:11:19.236 3643-3643/com.example.user.sample E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.user.sample, PID: 3643
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.user.sample/com.example.user.sample.MainActivity}: android.view.InflateException: Binary XML file line #23: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3190)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3300)
at android.app.ActivityThread.access$1000(ActivityThread.java:211)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1705)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6946)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
Caused by: android.view.InflateException: Binary XML file line #23: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:770)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:813)
at android.view.LayoutInflater.inflate(LayoutInflater.java:511)
at android.view.LayoutInflater.inflate(LayoutInflater.java:415)
at android.view.LayoutInflater.inflate(LayoutInflater.java:366)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:450)
at android.app.Activity.setContentView(Activity.java:2366)
at com.example.user.sample.MainActivity.onCreate(MainActivity.java:16)
at android.app.Activity.performCreate(Activity.java:6575)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1134)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3143)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3300)
at android.app.ActivityThread.access$1000(ActivityThread.java:211)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1705)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6946)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
Caused by: java.lang.RuntimeException: com.example.user.sample.MainActivity#197f8eef must implement OnListFragmentInteractionListener
at com.example.user.sample.MenuFragment.onAttach(MenuFragment.java:75)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1231)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1472)
at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1691)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:3413)
at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:120)
at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:378)
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:33)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:79)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:740)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:813)
at android.view.LayoutInflater.inflate(LayoutInflater.java:511)
at android.view.LayoutInflater.inflate(LayoutInflater.java:415)
at android.view.LayoutInflater.inflate(LayoutInflater.java:366)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:450)
at android.app.Activity.setContentView(Activity.java:2366)
at com.example.user.sample.MainActivity.onCreate(MainActivity.java:16)
at android.app.Activity.performCreate(Activity.java:6575)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1134)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3143)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3300)
at android.app.ActivityThread.access$1000(ActivityThread.java:211)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1705)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6946)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
The fragment will show when the ☰ is clicked. But the app crashes because of the existence of fragment inside the acitvity layout.
I already have a layout for the fragment and I didn't make any changes to it so I don't know if I need to post it here. Thanks
Your error is this
.RuntimeException: com.example.user.sample.MainActivity#197f8eef must implement OnListFragmentInteractionListener
So your activity needs to implement OnListFragmentInteractionListener.
So add
public class MainActivity extends FragmentActivity implements
OnListFragmentInteractionListener{
....
I want to show/hide fragment when i click the action bar menu item. But my app give me error when i click. Fragment coming on first run. When I want to hide fragment App give null error.
How can i solve this problem ?
Thanks in now.
Logcat
01-26 03:48:40.942 2295-2295/test.sy.myapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at android.app.BackStackRecord.run(BackStackRecord.java:661)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1435)
at android.app.FragmentManagerImpl$1.run(FragmentManager.java:441)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
LayerList.Java
package test.sy.myapplication;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class LayerList extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View mView = inflater.inflate(R.layout.layerlist,container,false);
return mView;
}
}
MainActivity.Java
package test.sy.myapplication;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
switch (item.getItemId()) {
case R.id.action_settings:
return true;
case R.id.showsth:
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.setCustomAnimations(android.R.animator.fade_in,
android.R.animator.fade_out);
ft.show(fm.findFragmentById(R.id.fragment));
ft.commit();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
ft.show(fm.findFragmentById(R.id.fragment));
this line causes the problem
fm.findFragmentById(R.id.fragment) returns null.
With this line you are trying to find a fragment in layout/activity_main which is previously added to R.id.fragment.
If you didn't add or replace fragment before, it is obvious to return null AMK
I fix this issue.
This situation caused by adding fragment without any framelayout.
Once add framelayout to main activity. And give it id;
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin" tools:context=".MainActivity">
<FrameLayout
android:layout_width="200dp"
android:layout_height="450dp"
android:layout_centerVertical="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="false"
android:id="#+id/frameLayout"></FrameLayout>
Second;
Create fragment with its activty. In this example our fragment name may be FragmentTest.java and our Fragments activity may be fragment_activity.xml.
And adding fragment to main activiy;
In Oncreate method you should add this line;
FragmentTest Mfragmenttest = new FragmentTest();
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
//R.id.frameLayout is our frame layouts id.
ft.add(R.id.frameLayout, Mfragmenttest , "Hello Fragment");
ft.commit
I am mainly looking for clarification and advice on this. In the app I am working on I setup a fragment for handling some basic controls and text, and moved the necessary XML from the activities layout file into the fragments layout file, without making any changes. However now when I run the app I get a NULLPOINTEREXCEPTION and it seems to be caused at line 19 in my GameStart activty when I try to set the textView by its ID. I have not changed the ID, only moved it to the fragment layout file, so I have two questions:
1) What exactly is the reason this is happening, because something similar happened before that I resolved but I don't see the reason it was happening in the reference docs on Android Developers
2) Any advice on how to fix this
Below is the GameStart activity, LogCat with the error, and the XML files in question. Thanks in advance, I've spent 2 hours now trying to find this answer.
EDITED FILES/LOGCAT BELOW
LogCat:
12-04 13:48:06.322 826-826/com.saphiric.simproject E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.saphiric.simproject/com.saphiric.simproject.GameStart}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2137)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:109)
at com.saphiric.simproject.GameStart.<init>(GameStart.java:25)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1130)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Starting Activity (The error occurs when the app tries to start the GameStart activity):
package com.saphiric.simproject;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
public class TitleMenu extends ActionBarActivity {
public void startGame(View view){
Intent gameStart = new Intent(this, GameStart.class);
startActivity(gameStart);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActionBar actionBar = getSupportActionBar();
actionBar.hide();
setContentView(R.layout.activity_main_menu);
}
}
Fragment XML
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- Relative layout to handle main interaction area -->
<RelativeLayout
android:id="#+id/relativeLayout"
android:layout_width="wrap_content"
android:layout_height="90dp"
android:layout_alignParentBottom="true"
android:background="#drawable/bg_text">
<TextView
android:id="#id/storyText"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:text="#string/story_opening_one"
android:textColor="#color/black" />
<Button
android:id="#+id/advanceButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#id/controlsFragment"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:background="#drawable/button_advance"
android:onClick="advanceGame" />
<Button
android:id="#+id/menuButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:layout_below="#id/advanceButton"
android:background="#drawable/menu_button" />
</RelativeLayout>
</RelativeLayout>
Fragment Class:
package com.saphiric.simproject;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* Created by Saphiric on 12/4/14.
*/
public class ControlsFragment extends Fragment {
/**
* Fragment Lifecycle Methods
*/
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
// Inflates the layout resource for the fragment
return inflater.inflate(R.layout.controls_fragment, container, false);
}
#Override
public void onPause(){
}
}
GameStart activity:
package com.saphiric.simproject;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
/**
* Created by Saphiric on 11/12/14.
*/
public class GameStart extends Activity{
/**
* Necessary activity variables
*/
protected int clickCount = 0;
TextView storyText = (TextView) findViewById(R.id.storyText);
/**
* Sets up and alert dialogue builder for making decisions
* This will need to be revised during production
*/
AlertDialog.Builder decisionTime = new AlertDialog.Builder(getApplicationContext());
/**
* Handles advancing non character based conversations at the beginning
* of the story.
* If the player decides to investigate the scream, then the app loads the appropriate activity, and the same with the
* decision to leave the scene.
*/
public void advanceGame(View view){
clickCount = clickCount + 1; // Increments clickCount by 1 per click
if (clickCount == 1){
storyText.setText(R.string.story_opening_two);
} else if(clickCount == 2){
decisionTime.setTitle("Decision Time!"); // Sets the title for the decision box
decisionTime.setCancelable(false); // Sets it so that the decision can not be cancelled.
decisionTime.setPositiveButton("Investigate",new DialogInterface.OnClickListener() { // Sets up the positive button
#Override
public void onClick(DialogInterface dialog, int which) {
}
});
decisionTime.setNegativeButton("Leave the scene.",new DialogInterface.OnClickListener() { // Sets up the negative button
#Override
public void onClick(DialogInterface dialog, int which) {
}
});
}
}
/**
* Android activity methods
* #param savedInstanceState is the apps savedInstanceState
*/
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_start);
}
}
GameStart Layout XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/bg_school_gate"
android:orientation="vertical">
<fragment
android:id="#+id/controlsFragment"
android:name="com.saphiric.simproject.ControlsFragment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:layout="#layout/controls_fragment" />
</RelativeLayout>
No, you don't have any fragment here, read more on How to use fragments.
But that's not your problem it should work the way you did it.
The only problem is that you're calling findViewById in your constructor, or even before that.
findViewById only works if you have a UI, so you must do all UI initialization after setContentView in onCreate!
TextView storyText;
...
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_start);
storyText = (TextView) findViewById(R.id.storyText);
}
Also don't forget to call show() on decisionTime.
TextView storyText = (TextView) findViewById(R.id.storyText);
This should only be called after you set your contentview.
The final result should be:
TextView storyText;
And then on onCreate
setContentView(R.layout.activity_game_start);
storyText = (TextView) findViewById(R.id.storyText);
1) The reason this is happening is that the view has not yet been instantiated at the time you are trying to get it's reference.
2) How to fix it: if you have a Fragment, then you should get a reference to it's View's in the Fragment.onCreateView() method. Then you can setup the Activity to talk to the Fragment to do whatever changes you need to the View.
Hi I have been creating an app that implements a cutom sliding navigation drawer. However, I keep on receiving an error shown on the title.
Logs:
10-30 15:38:20.510: E/AndroidRuntime(1863): FATAL EXCEPTION: main
10-30 15:38:20.510: E/AndroidRuntime(1863): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobextph.krispykreme/com.mobextph.krispykreme.ParentActivity}: java.lang.IllegalArgumentException: View android.widget.LinearLayout{5321e6b8 V.E..... ......ID 0,0-0,0 #7f090002 app:id/left_drawer} is not a sliding drawer
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.os.Handler.dispatchMessage(Handler.java:99)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.os.Looper.loop(Looper.java:137)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.app.ActivityThread.main(ActivityThread.java:5041)
10-30 15:38:20.510: E/AndroidRuntime(1863): at java.lang.reflect.Method.invokeNative(Native Method)
10-30 15:38:20.510: E/AndroidRuntime(1863): at java.lang.reflect.Method.invoke(Method.java:511)
10-30 15:38:20.510: E/AndroidRuntime(1863): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-30 15:38:20.510: E/AndroidRuntime(1863): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-30 15:38:20.510: E/AndroidRuntime(1863): at dalvik.system.NativeStart.main(Native Method)
10-30 15:38:20.510: E/AndroidRuntime(1863): Caused by: java.lang.IllegalArgumentException: View android.widget.LinearLayout{5321e6b8 V.E..... ......ID 0,0-0,0 #7f090002 app:id/left_drawer} is not a sliding drawer
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.support.v4.widget.DrawerLayout.closeDrawer(DrawerLayout.java:1170)
10-30 15:38:20.510: E/AndroidRuntime(1863): at com.mobextph.krispykreme.ParentActivity.changeFragment(ParentActivity.java:141)
10-30 15:38:20.510: E/AndroidRuntime(1863): at com.mobextph.krispykreme.ParentActivity.onCreate(ParentActivity.java:111)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.app.Activity.performCreate(Activity.java:5104)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
10-30 15:38:20.510: E/AndroidRuntime(1863): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
The Main Activity class is:
package com.mobextph.krispykreme;
import java.util.ArrayList;
import com.mobextph.krispykreme.constants.Constants;
import android.R.color;
import android.content.res.Configuration;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.DrawerLayout;
import android.view.Gravity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.ListView;
public class ParentActivity extends FragmentActivity {
private Fragment changedFragment= null;
private FragmentManager fm;
private DrawerLayout mDrawerLayout;
private LinearLayout linearLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
// nav drawer title
private CharSequence mDrawerTitle;
// used to store app title
private CharSequence mTitle;
// slide menu items
private String[] navMenuTitles;
private ArrayList<String> navDrawerItems;
private ArrayAdapter<String> adapter;
private String[] menuItem= {"ORDER", "STAMP CARD", "REWARDS", "STORES", "FAVORITES"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Drawable d;
// getActionBar().setBackgroundDrawable(new ColorDrawable(getResources().getColor(android.R.color.transparent)));
/*Slider*/
mTitle = mDrawerTitle = getTitle();
navMenuTitles= menuItem;
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.list_slidermenu);
linearLayout = (LinearLayout) findViewById(R.id.left_drawer);
mDrawerList.setAdapter(new ArrayAdapter<String>(this, R.layout.drawer_list_item, R.id.title, menuItem));
mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
R.drawable.button_menu, //nav menu toggle icon
R.string.app_name, // nav drawer open - description for accessibility
R.string.app_name // nav drawer close - description for accessibility
) {
public void onDrawerClosed(View view) {
getActionBar().setTitle(mTitle);
// calling onPrepareOptionsMenu() to show action bar icons
invalidateOptionsMenu();
}
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle(mDrawerTitle);
// calling onPrepareOptionsMenu() to hide action bar icons
invalidateOptionsMenu();
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
if (savedInstanceState == null) {
// on first time display view for first nav item
// changeFragment(-1);
}
fm = getSupportFragmentManager();
// DatabaseHandler db= new DatabaseHandler(this);
//
// for(int i = 0; i < 2; i++){
// db.insertFavorite(Constants.id[i], Constants.imageItem[i],
// Constants.title[i], Constants.price[i], Constants.desc[i],
// Constants.status[i]);
// }
changeFragment(-1);
}
public void changeFragment(int fragment){
FragmentTransaction transaction = fm.beginTransaction();
changedFragment = null;
switch(fragment){
case -1:
changedFragment = new HomeFragment();
// mDrawerLayout.closeDrawers();
break;
case Constants.ORDER_SCREEN_CLICKED:
changedFragment = new OrderFragment();
break;
case Constants.FAVORITES_SCREEN_CLICKED:
changedFragment = new FavoritesFragment();
break;
}
if (changedFragment != null) {
transaction.replace(R.id.fragment_holder, changedFragment);
transaction
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
transaction.addToBackStack(null);
transaction.commit();
mDrawerList.setItemChecked(fragment, true);
mDrawerList.setSelection(fragment);
mDrawerLayout.closeDrawer(linearLayout);
}
}
private class SlideMenuClickListener implements
ListView.OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// display view for selected nav drawer item
int fragment = 0;
if(position == 0)
fragment= Constants.ORDER_SCREEN_CLICKED;
else if(position == 4)
fragment= Constants.FAVORITES_SCREEN_CLICKED;
changeFragment(fragment);
}
}
// #Override
// public boolean onCreateOptionsMenu(Menu menu) {
// // Inflate the menu; this adds items to the action bar if it is present.
// getMenuInflater().inflate(R.menu.main, menu);
// return true;
// }
//
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
// int id = item.getItemId();
// if (id == R.id.action_settings) {
// return true;
// }
// return super.onOptionsItemSelected(item);
if(mDrawerToggle.onOptionsItemSelected(item))
return true;
switch(item.getItemId()){
default: return super.onOptionsItemSelected(item);
}
}
/**
* When using the ActionBarDrawerToggle, you must call it during
* onPostCreate() and onConfigurationChanged()...
*/
#Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
mDrawerToggle.onConfigurationChanged(newConfig);
}
}
The view code that shows a linear layout for the sliding drawer and a listview is:
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<FrameLayout
android:id="#+id/fragment_holder"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<LinearLayout
android:id="#+id/left_drawer"
android:layout_width="260dp"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#008265"
android:gravity= "left" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageView
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="1"
android:src="#drawable/icon_login"/>
<TextView
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_gravity="center"
android:text="LOGIN"
android:textSize="15dp"
android:paddingLeft="5dp"
android:paddingRight="0dp"/>
<TextView
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_gravity="center"
android:text="|"
android:gravity="center"
android:textSize="15dp"/>
<TextView
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_gravity="center"
android:text="SIGN UP"
android:textSize="15dp"
android:paddingLeft="0dp"
android:paddingRight="5dp"/>
</LinearLayout>
<ListView
android:id="#+id/list_slidermenu"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="start"
android:choiceMode="singleChoice"
android:divider="#color/list_divider"
android:dividerHeight="1dp"
android:listSelector="#drawable/list_selector"
android:gravity= "left" />
</LinearLayout>
</android.support.v4.widget.DrawerLayout>
Try setting
layout_gravity="start" or layout_gravity="left"
in your left_drawer instead of gravity
I am stuck with an idea.
I am trying to implement a feature in a android application.
I have an edittext and a button, if I enter 3 in edittext
and press the button I want to go to another activity which will be having 3 buttons.
If i enter 10 I wanna go to another activity where to display 10 buttons.
I know how to make such switch, I don't know how to do it dynamically ,
I want to make for values between 0 and 10 and I don't want to have 10 fragments .
Plaese give me solution to achieve it ..
Thanks..
Untill now:
mainactivity.java:
package com.example.instances_temperature;
import com.example.instances_temperature.Tabel;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
EditText instances;
Button ok;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ok = (Button) findViewById(R.id.ok);
instances = (EditText) findViewById(R.id.instances);
ok.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (instances.getText().toString().length() > 0)
{
int value = Integer.parseInt(instances.getText().toString());;
if(value > 10)
Toast.makeText(getApplicationContext(), "Enter a value between 0 and 10!", Toast.LENGTH_SHORT).show();
else
if(value<0)
Toast.makeText(getApplicationContext(), "Enter a value between 0 and 10!", Toast.LENGTH_SHORT).show();
else
if(value >= 0 && value <=10)
{
schimba(v);
}
}
else
{
Toast.makeText(getApplicationContext(), "Enter a value between 0 and 10!", Toast.LENGTH_SHORT).show();
}
}
});
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
public void schimba(View view){
int value = Integer.parseInt(instances.getText().toString());;
Intent intent = new Intent(this, Tabel.class);
intent.putExtra("max", value);
startActivity(intent);
}
}
activity_main.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.instances_temperature.MainActivity"
tools:ignore="MergeRootFrame" >
<TextView
android:id="#+id/ShowValue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="139dp"
android:text="Instances No.:"
android:textAppearance="?android:attr/textAppearanceLarge" />
<EditText
android:id="#+id/instances"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:ems="10"
android:inputType="number" >
<requestFocus />
</EditText>
<Button
android:id="#+id/ok"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/instances"
android:layout_centerHorizontal="true"
android:layout_marginTop="48dp"
android:text="Ok"
android:onClick="schimba" />
</RelativeLayout>
tabel.java:
package com.example.instances_temperature;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.os.Build;
public class Tabel extends ActionBarActivity {
int i;
int value;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tabel);
Intent intentObject = getIntent();
value = intentObject.getIntExtra("max", 0);
LinearLayout layout = (LinearLayout)findViewById(R.id.container);
for(i=1;i<=value;i++)
{
LayoutInflater layoutinflate = null;
layoutinflate = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
final View rowview = layoutinflate.inflate( R.layout.ShowMe, null);
TextView showvalue;
showvalue = (TextView) rowview.findViewById(R.id.showid);
showvalue.setText(""+value);
layout.addView(rowview);
}
//showvalue.setText(String.valueOf(getIntent().getExtras().getInt("max")));
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.tabel, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_tabel,
container, false);
return rootView;
}
}
}
activity_tabel.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.instances_temperature.Tabel"
tools:ignore="MergeRootFrame" >
</LinearLayout>
LinearLayout code of inflation_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/inflationn"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/ShowMe"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge" />
</LinearLayout>
LogCat error:
04-24 06:21:04.244: E/AndroidRuntime(269): FATAL EXCEPTION: main
04-24 06:21:04.244: E/AndroidRuntime(269): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.instances_temperature/com.example.instances_temperature.Tabel}: java.lang.NullPointerException
04-24 06:21:04.244: E/AndroidRuntime(269): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-24 06:21:04.244: E/AndroidRuntime(269): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-24 06:21:04.244: E/AndroidRuntime(269): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-24 06:21:04.244: E/AndroidRuntime(269): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-24 06:21:04.244: E/AndroidRuntime(269): at android.os.Handler.dispatchMessage(Handler.java:99)
04-24 06:21:04.244: E/AndroidRuntime(269): at android.os.Looper.loop(Looper.java:123)
04-24 06:21:04.244: E/AndroidRuntime(269): at android.app.ActivityThread.main(ActivityThread.java:4627)
04-24 06:21:04.244: E/AndroidRuntime(269): at java.lang.reflect.Method.invokeNative(Native Method)
04-24 06:21:04.244: E/AndroidRuntime(269): at java.lang.reflect.Method.invoke(Method.java:521)
04-24 06:21:04.244: E/AndroidRuntime(269): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-24 06:21:04.244: E/AndroidRuntime(269): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-24 06:21:04.244: E/AndroidRuntime(269): at dalvik.system.NativeStart.main(Native Method)
04-24 06:21:04.244: E/AndroidRuntime(269): Caused by: java.lang.NullPointerException
04-24 06:21:04.244: E/AndroidRuntime(269): at com.example.instances_temperature.Tabel.onCreate(Tabel.java:42)
04-24 06:21:04.244: E/AndroidRuntime(269): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-24 06:21:04.244: E/AndroidRuntime(269): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
04-24 06:21:04.244: E/AndroidRuntime(269): ... 11 more
You can get the value from the editText by...
String value= EditText.getText().toString();
Pass the value to another activity (Activity2) through Intent
Now in Activity2 you write this code in the onCreate()
for(int i=1 ; i<= value ; i++){
Button b = new Button(getApplicationContext());
LinearLayout.addView(b);
}
Answer to your edited question.....
main xml file activity_table:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/layout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
</LinearLayout>
layout file to be inflated layout_inflate:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/ShowValue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Text" />
</LinearLayout>
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tabel);
Intent intentObject = getIntent();
value = intentObject.getIntExtra("max", 0);
LinearLayout layout= (LinearLayout)findViewById(R.id.layout)
for(i=0;i<=value;i++)
{
LayoutInflater layoutinflate = null;
layoutinflate = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowview = layoutinflate.inflate( R.layout.layout_inflate, null);
TextView showvalue;
showvalue = (TextView) rowview.findViewById(R.id.ShowValue);
showvalue.setText(""+value);
layout.addView(rowview);
}
You can retrieve the EditText value on tha Button click. And pass the Value with the intent.
In that Activity you can build your logic Using Swicth cases. Then you can add the number of Buttons dynamically (eg:- for(i=0;i<yourValue;i++) yourValue is got From intent.)