So I just started learning to develop Android apps, and I have a programming background (Python mainly), so I somewhat know what I'm doing. I'm having a problem with using startActivity(). I've commented code to figure out exactly where the error gets thrown, and it happens right as startActivity() is encountered. The error I get is from the emulator and it is just a popup window that says, "Unfortunately, Test has stopped." (Test is my program name) after I click my button. My code is this
package com.test.test;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
public class TestActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.test.test.MESSAGE";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public class DisplayMessageActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
}
public void sendMessage(View view) {
setContentView(R.layout.main);
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.textBox1);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
}
Now I know that won't do anything yet, but why is it crashing?
My XML:
<?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="horizontal" >
<EditText android:id="#+id/textBox1"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/textBox1Hint" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button1"
android:onClick="sendMessage" />
</LinearLayout>
My manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.test.test"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="15" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name" >
<activity
android:name=".TestActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".DisplayMessageActivity" >
</activity>
</application>
</manifest>
I saw that a lot of other people were having problems with this because they had not declared their activities in the manifest, but I think I have done so properly. Any help would be so greatly appreciated.
One possible problem is that
EditText editText = (EditText) findViewById(R.id.textBox1);
returns null because you dont set anywhere the layout for your activity (with setContentView)
If your editetext is included in view (passed to sendMessage), you can find it with
EditText editText = (EditText) view.findViewById(R.id.textBox1);
I think problem is you are on DisplayMessageActivity and starting the same activity.
What you need to do is start test activity and call DisplayMessageActivity from intent.
Use separate files for TestActivity and DisplayMessageActivity classes. In your given code you are not specifying a layout for your DisplayMessageActivity activity using setContentView.
the problem is this,
you declare in the manifest that the main class is TestActivity:
<activity
android:name=".TestActivity"
android:label="#string/app_name" >
but you wanted to start DisplayMessageActivity,
so, change this to the following:
public class TestActivity extends Activity {
#Override
I can't understand what you are actually trying to achieve by starting the same activity again. Try this,
public class DisplayMessageActivity extends Activity {
private String message ;
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setLayout(R.layout.<name of the xml file> ); // change the name if it is not in layout folder
EditText editText = (EditText) findViewById(R.id.textBox1);
String message = editText.getText().toString();
Button submitBtn = (Button) findViewById(R.id.button1);
submitBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Toast toast = Toast.makeText(DisplayMessageActivity.this,
message,
Toast.LENGTH_SHORT);
toast.show();
}});
}
}
The above code simply displays the String, This is just a sample code... Hope that helps!!!
EDIT
To run this code you must also add id tag to your Button Tag inside XML file having value button1..
Actullay you have created the Activity inside activity. Which is not much pref-able but if want to stick with that then you have to change the android:name=".DisplayMessageActivity" to
Related
This question already has answers here:
What does a "Cannot find symbol" or "Cannot resolve symbol" error mean?
(18 answers)
Closed 10 months ago.
I'm a beginner in Android , so please pardon my ignorance.
As I was learning Android programming,I followed the book and the codes are as follows:
FirstActivity.java
package com.example.activitytest;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
public class FirstActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.first_layout);
Button button1 = (Button)findViewById(R.id.button_1);
button1.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
Toast.makeText(FirstActivity.this, "You clicked Button 1", Toast.LENGTH_SHORT).show();
}
});
}
}
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.activitytest">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/Theme.Activitytest">
<activity
android:name=".FirstActivity"
android:label="This is FirstActivity"
android:exported="true">
<intent-filter>
<action android:name = "android.intent.action.MAIN"/>
<category android:name = "android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
</manifest>
first_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="#+id/button_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/button_1"
tools:ignore="MissingConstraints"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="1dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
And android studio reports that:
error: cannot find symbol
Button button1 = (Button)findViewById(R.id.button_1);
^
symbol: class Button
location: class FirstActivity
and then I search stackoverflow to find the method to debug.
I once tried this method:
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
Button buttonClick = (Button)rootView.findViewById(R.id.button);
buttonClick.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
onButtonClick((Button) view);
}
});
But it still does not work.As I am just a beginner, I can't find a way to debug.
Can someone help me? Thank you for that.
As I can see in your code that in xml you have assigned the id to the button which is
android:id="#+id/button_1"
but you are trying to access the wrong id here
Button buttonClick = (Button)rootView.findViewById(R.id.button);
and if you are in activity there is no need of rootView you can simply access the button with findViewById(R.id.button_1)
Also it is missing in your first_layout.xml
tools:context=".FirstActivity"
add this to the constraintLayout in xml
also add import
import android.widget.Button;
And I will suggest you to use viewBinding it will help you a lot in this case
add this line
import android.widget.Button;
FirstActivity.java
package com.example.activitytest;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
import android.widget.Button;
public class FirstActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.first_layout);
Button button1 = (Button)findViewById(R.id.button_1);
button1.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
Toast.makeText(FirstActivity.this, "You clicked Button 1", Toast.LENGTH_SHORT).show();
}
});
}
}
Here's my code for clicking the button from my class showInforActivity:
btnRegister.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(showInfoActivity.this, InformationFragment.class);
startActivity(intent);
}
});
Whenever I click the button I got error Unable to find explicit activity class {com.example.drawerapplication/com.example.drawerapplication.ui.information.InformationFragment}; have you declared this activity in your AndroidManifest.xml? and it loads the previous class and layout instead of loading this
InformationFragment class:
package com.example.drawerapplication.ui.information;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import com.example.drawerapplication.databinding.FragmentInformationBinding;
public class InformationFragment extends Fragment {
private FragmentInformationBinding binding;
private EditText name, address, age, contact;
private Button btnAdd, btnViewData;
DatabaseHelper mDatabaseHelper;
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
binding = FragmentInformationBinding.inflate(inflater, container, false);
View root = binding.getRoot();
name = binding.name;
address = binding.address;
age = binding.age;
contact = binding.contact;
btnAdd = binding.add;
btnViewData = binding.viewdata;
mDatabaseHelper = new DatabaseHelper(getActivity());
btnAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (name.length() != 0 && address.length() != 0
&& age.length() != 0 && contact.length() != 0){
mDatabaseHelper.addData(name.getText().toString(), address.getText().toString(),
age.getText().toString().trim(), Long.valueOf(contact.getText().toString().trim()));
toastMessages("Data Successfully Inserted!");
}else {
toastMessages("Please complete all the requirements needed");
}
}
});
btnViewData.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(getContext(), ListDataActivity.class);
startActivity(intent);
}
});
return root;
}
#Override
public void onDestroyView() {
super.onDestroyView();
binding = null;
}
private void toastMessages(String message){
Toast.makeText(getContext(),message,Toast.LENGTH_SHORT).show();
}
}
The layout of this InformationFragment is fragment_information:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".ui.information.InformationFragment"
android:layout_marginStart="10dp"
android:layout_marginEnd="10dp">
...
Heres my **AndroidManifest file:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.example.drawerapplication">
<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
tools:ignore="ScopedStorage" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/Theme.DrawerApplication">
<activity android:name=".ui.information.ListDataActivity"/>
<activity android:name=".ui.information.showInfoActivity"/>
<activity
android:name=".MainActivity"
android:exported="true"
android:label="#string/app_name"
android:theme="#style/Theme.DrawerApplication.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
I tried adding InformationFragment there however, it says Class referenced in the manifest, com.example.drawerapplication.InformationFragment, was not found in the project or the libraries
Please let me know what I'm missing or if you need more information. Thanks!
You cannot use an Intent to start/create a Fragment much like you would for an Activity. A Fragment actually lives inside an Activity i.e. its lifecycle is bound to an Activity. To start a Fragment you have to use the FragmentManager that is available with the Activity instance
This error is coming up because Android thinks that your InformationFragment is an Activity rather than a Fragment and hence it is asking you if you have declared it in your AndroidManifest.xml file because as the rule says, you need to have each Activity in your app declared inside the AndroidManifest.xml file
So, now you can use something like this, inside your showInfoActivity. Technically there are many solutions available as to what you could essentially do and that's why I linked you to all possible solutions rather than just writing them here
You can not use Intent for navigate to Fragment from a Activity.
For this reason you are getting this error. As, Intent receive 2 parameter Intent(FromActivity, ToActivity.class) . you are using fragment in 2nd parameter. We know that, when we create a activity then it it declared with AndroidManifest.xml file. Here, in your manifest file there are not any activity called InformationFragment.
You can learn Android Navigation Component to easily communicate with Activity and fragments.
I’m following the android tutorial First App in the link below:
https://developer.android.com/training/basics/firstapp/starting-activity.html
The app can be launched in the emulator but the problem is when I click on the button “send, the application crashed with the message “unfortunately, my fist app has stopped”.
I think I did follow the instructions in the tutorial and can’t figure out where is the problem from.
Logcat send this message:
02-12 16:19:36.031: E/AndroidRuntime(786): java.lang.RuntimeException:
Unable to instantiate activity
ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.DisplayMessageActivity}:
java.lang.NullPointerException
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="horizontal">
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
</LinearLayout>
MAinActivity.java
package com.example.myfirstapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
// Do something in response to button
}
#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.main, menu);
return true;
}
}
activity_display_message.xml
<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: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=".DisplayMessageActivity" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
</RelativeLayout>
DisplayMessageActivity.java
package com.example.myfirstapp;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.MenuItem;
import android.widget.TextView;
public class DisplayMessageActivity extends Activity {
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
#SuppressLint("NewApi")
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
// Make sure we're running on Honeycomb or higher to use ActionBar APIs
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
// Show the Up button in the action bar.
getActionBar().setDisplayHomeAsUpEnabled(true);
}
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
}
MyFirstApp Manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myfirstapp"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.myfirstapp.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.example.myfirstapp.DisplayMessageActivity"
android:label="#string/title_activity_display_message"
android:parentActivityName="com.example.myfirstapp.MainActivity" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.myfirstapp.MainActivity" />
</activity>
</application>
</manifest>
Thank you for your help
I believe the problem is
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
before onCreate(). Intent needs a Context which isn't available until the Activity has been created. Remove those lines since you already have it in onCreate().
Also, when it crashes, post your full logcat because it will tell us, usually, exactly where and what the problem is.
I am a beginner in Android, and I need some advice/help with the following issue as I'm doing an Android tutorial http://developer.android.com/training/basics/firstapp/starting-activity.html#AddToManifest. I got a little problem here when running the app it displays a BLANK ACTIVITY of myfirstapp (both on emulator and my Samsung Galaxy S2) - it doesn't show up anything on the app - no text field, no button.
MainActivity.java:
package com.example.myfirstapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE ="com.example.myfirstapp.MESSAGE";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
}
#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;
}
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
}
activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<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:baselineAligned="true"
android:orientation="horizontal" >
<EditText
android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
</LinearLayout>
activity_display_message.xml:
<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: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=".DisplayMessageActivity" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
</RelativeLayout>
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myfirstapp"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.myfirstapp.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".DisplayMessageActivity"
android:label="#string/title_activity_display_message"
android:parentActivityName="com.example.myfirstapp.MainActivity" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.myfirstapp.MainActivity" />
</activity>
</application>
</manifest>
However when I remove this particular piece of code from my main activity:
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
It will run an app as normally showing everything although it won't process the text entered. Once you click on the button it will only show up a new activity with Hello World. Any ideas where the problem occurs?
I hope you are aware that in the tutorial two classes are used - MainActivity and DisplayMessageActivity - it seems you've merged them into one class accidentally.
The following code should be in the onCreate method of DisplayMessageActivity.java and not in MainActivity.java
// Get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
Are you getting anything in the message variable. If it is empty then nothing will be set in the setText(message) and hence nothing will be displayed.
I have 2 files: main_activity.xml and home.xml. I made a button in main_activity.xml
Here is the code snippet:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:background="#drawable/splash_background"
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" >
<Button
android:id="#+id/Home"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginRight="43dp"
android:onClick="home"
android:text="Home" />
</RelativeLayout>
And then, I have my home.xml. I want the button to open up home.xml. How can i do this?
I don't know any java and I am new to android development.
Here is my home.xml below:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:background="#drawable/app_bg"
android:layout_height="match_parent"
android:orientation="vertical" >
</LinearLayout>
And below is my AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.idozer"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="false"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.idozer.SplashActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name="com.example.idozer.MainActivity"
android:label="#string/app_name" >
</activity>
</application>
</manifest>
And that's all I have. Please, if you reply, tell me where to add the code such as the directory or between code snippets.
For managing click activity in android ,you can do as below
Implement OnClickListener on YourActivity.java class like
public class MainActivity extends Activity implements OnClickListener
Then, declare your button in .java class like
Button btn = (Button) findViewById(R.id.btnPlay);
Then use button btn variable as below
btn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
myClick(v); /* my method to call new intent or activity */
}
});
Handle the click event:
public void myClick(View v) {
Intent intent = new Intent(**this, Swipe.class**);
startActivity(intent);// for calling the activity
}
you also need to register your activity(.java) in android manifest as below
<activity
android:name=".Swipe"
android:screenOrientation="landscape" >
</activity>
You can use this code.
Android: OnClickListener
In our activity class we add the onclick method.
In our activity class we add the onclick method.
//On click event for button1
public void button1OnClick(View v) {
//Inform the user the button has been clicked
Toast.makeText(this, "Button1 clicked.", Toast.LENGTH_SHORT).show();
}
In the layout file we add a reference to the onclick handler in the
activity. The app will automatically bind the onclick method to the
view (in this case button1)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button1"
android:onClick="button1OnClick"/>
</LinearLayout>
create another class goto your project right click and click class and create Home.
In that Home class file extends activity and add code like this
public class Home extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home);
}
}
in splash activity class add this line
Intent intent = new Intent(SplashActivity.this,Home.class);
startActivity(intent);
add Home activity class in your android manifest file
<activity android:name="com.example.idozer.Home"
android:label="#string/app_name" >
</activity>
I will give you just a little bit to get you started as this answer may help others that are having trouble with using onClick() this way but you really need to learn Java and go through the Android Docs so you can ask better questions
You need to read Here about Actviities and how to create them. Then in your code you will have a function
public void home(View v) //the name of this function comes from where you declared in your manifest `android:onClick="home"
{
Intent intent (MainActivity.this, HomeActivity.class); //MainActivity is the name of current activity and HomeActivity is the name of the activity you want to start
can add intent extras/flags/categories here
startActivity(intent);
}
You also need to add the HomeActivity in your manifest as you have for the other Activities.
But you really need to go through the docs and do some tutorials to get an idea of how the Android framework operates and you need to learn Java to make your life a whole lot easier. Besides the previous two links I have given, also see this post about click events as there are different ways to use onClick()
I hope this is enough to get you started and I really hope you go through the docs to get a better understanding of what you are doing. Good luck to you!
Another important link to get started
Intents
android:onClick was added in API level 4 to make it easier, more Javascript-web-like, and drive everything from the XML. What it does internally is add an OnClickListener on the Button, which calls your home method.
<Button
android:id="#+id/Home"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginRight="43dp"
android:onClick="home"
android:text="Home" />
.
public void home(View view){
Intent intent=new Intent (view.getContext(),Luton.class);
this.startActivity(intent);
}
In your activity class
Using java code you can do button click by getting the id of the button from xml.
<Button
android:id="#+id/myHomeButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginRight="43dp"
android:text="Home" />
.
Button button= (Button) findViewById(R.id.myHomeButton);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//do whatever you want on button click
}
});
Both are exactly the same
Button button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(MainActivity.this, "Button Clicked", Toast.LENGTH_SHORT).show();
}
});