Develop Reference

How to call findViewById(R.id.textView) in another class than MainActivity?

I am new to Android.
I am trying to refer a View by Id from a separate class than MainActivity.
Note: My app has single activity.
Main Activity:
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState)//Activity Oncreate callback
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) //Oncreate Options_menu callback
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main_menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.option1:
//Here am calling a method from another class
SecondClass secondClassObject=new SecondClass();
secondClassObject.method1();
}
return true;
}
Second Class:
public class SecondClass {
public void method1(){
TextView tv1 = (TextView)findViewById(R.id.textView);
tv1.setText("");
}
}
How to refer to the textView by ID in the SecondClass? How to set the context as MainActivity in this SecondClass?

Add an Activity parameter for your method
public void method1(Activity act){
TextView tv1 = (TextView)act.findViewById(R.id.textView);
tv1.setText("");
}
From your activity define an Activity variable Activity act; so as to use it across other functions .Assign a value of your Activity to the variable act=this; and finaly use it on the function you want.
public class MainActivity extends AppCompatActivity {
Activity act;
#Override
protected void onCreate(Bundle savedInstanceState)//Activity Oncreate callback
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
act=this;
}
#Override
public boolean onCreateOptionsMenu(Menu menu) //Oncreate Options_menu callback
{
act=this;
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main_menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.option1:
//Here am calling a method from another class
//SecondClass secondClassObject=new SecondClass();
//secondClassObject.method1();
SecondClass secondClassObject=new SecondClass();
secondClassObject.method1(act);
}
return true;
}
you can also pass the parent layout view
public void method1(View act){
TextView tv1 = (TextView)act.findViewById(R.id.textView);
tv1.setText("");
}
And call it like so
SecondClass secondClassObject=new SecondClass();
secondClassObject.method1(findViewById(R.id.your_parent_layout));
Avoid using passing Activity method if its not absolutely necessary to avoid possibilities of memory leaks.

OnCreate method is not called (Sunshine app)

I'm working on the android self study Sunshine app and I'm having trouble getting extra menu entries in the action bar.
The most likely reason I've found, is that the OnCreate method of my frame class is not being called and thus the menu is not being inflated.
Here's my MainActivity code:
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d("MainActivity","OnCreate Started 1");
if (savedInstanceState == null) {
Log.d("MainActivity","OnCreate Started 2");
ForecastFragment MyFragment = new ForecastFragment();
if (MyFragment == null){
Log.d("MainActivity","OnCreate Started 3");
}
else{
getSupportFragmentManager().beginTransaction()
.add(R.id.container, MyFragment)
.commit();}
}
}
Here is now the code of my ForecastFragment class:
public class ForecastFragment extends Fragment {
public ForecastFragment() {
}
//#Override
protected void OnCreate(Bundle savedInstanceState){
Log.d("Forecastfragment","OnCreate Started");
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
// Inflate the menu; this adds items to the action bar if it is present.
inflater.inflate(R.menu.forecastfragment, menu);
}
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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_refresh) {
FetchWeatherTask WeatherTask = new FetchWeatherTask();
WeatherTask.execute();
return true;
}
return super.onOptionsItemSelected(item);
}
When I run the app, I don't see the logging that the OnCreate method of the ForecastFragment class is being called.
Any ideas?

This is not the exact inherited onCreate method of Fragment
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.i(TAG, "onCreate()");
}
it should be onCreate not OnCreate

How to Extend Two Classes in Android?

I need to extend Two classes from a Single Class.My class Wants to extend Both ListActivity & MainActivity.
I found a question similar to this.
But i don't know how to Implement this https://stackoverflow.com/a/5836735/2781359
Thanks for your Help.
The Class which has to be Extended is ConnectionEditActivity.
public class ConnectionEditActivity extends ListActivity implements OnClickListener
{
public static Connection connectionParam;
private Connection connection;
private Button save;
private EditText name;
private EditText password;
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
this.connection = connectionParam;
this.save = (Button) this.findViewById(R.id.save);
this.save.setOnClickListener(this);
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.GINGERBREAD)
{
// Don't need the Save button on newer devices
android.widget.LinearLayout.LayoutParams a = (LayoutParams) this.save.getLayoutParams();
a.height = 0;
this.save.setLayoutParams(a);
this.save.forceLayout();
}
this.name = (EditText) this.findViewById(R.id.name);
this.password = (EditText) this.findViewById(R.id.password);
}
#Override
public boolean onCreateOptionsMenu(android.view.Menu menu)
{
// Inflate the menu items for use in the action bar
android.view.MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.connection_edit_menu, menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(android.view.MenuItem item)
{
// Handle presses on the action bar items
switch (item.getItemId())
{
case R.id.action_save:
this.finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
protected void onResume()
{
super.onResume();
this.name.setText(this.connection.getName());
this.password.setText(this.connection.getPassword());
}
protected void onPause()
{
super.onPause();
this.connection.setName(this.name.getText().toString());
this.connection.setPassword(this.password.getText().toString());
finish();
}
public void onClick(View v)
{
if (v == this.save)
{
this.finish();
}
}
}
Mainactivity
public abstract class MainActivity extends ActionBarActivity
{
protected ListView mDrawerList;
protected DrawerLayout mDrawer;
private CustomActionBarDrawerToggle mDrawerToggle;
private String[] menuItems;
String LOG_TAG = "Remote It";
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
supportRequestWindowFeature(WindowCompat.FEATURE_ACTION_BAR);
// getSupportActionBar().hide();
setContentView(R.layout.activity_main_drawer);
// enable ActionBar app icon to behave as action to toggle nav drawer
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
mDrawer = (DrawerLayout) findViewById(R.id.drawer_layout);
// set a custom shadow that overlays the main content when the drawer
// opens
mDrawer.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
_initMenu();
mDrawerToggle = new CustomActionBarDrawerToggle(this, mDrawer);
mDrawer.setDrawerListener(mDrawerToggle);
}
private void _initMenu()
{
NsMenuAdapter mAdapter = new NsMenuAdapter(this);
// Add Header
mAdapter.addHeader(R.string.ns_menu_main_header);
// Add first block
menuItems = getResources().getStringArray(R.array.ns_menu_items);
String[] menuItemsIcon = getResources().getStringArray(R.array.ns_menu_items_icon);
int res = 0;
for (String item : menuItems)
{
int id_title = getResources().getIdentifier(item, "string", this.getPackageName());
int id_icon = getResources().getIdentifier(menuItemsIcon[res], "drawable", this.getPackageName());
NsMenuItemModel mItem = new NsMenuItemModel(id_title, id_icon);
// if (res==1) mItem.counter=12; //it is just an example...
// if (res==3) mItem.counter=3; //it is just an example...
mAdapter.addItem(mItem);
res++;
}
// Second Block
mAdapter.addHeader(R.string.ns_menu_main_header2);
menuItems = getResources().getStringArray(R.array.ns_menu_itemss);
String[] menuItemsIcons = getResources().getStringArray(R.array.ns_menu_items_iconss);
int ress = 0;
for (String item : menuItems)
{
int id_title = getResources().getIdentifier(item, "string", this.getPackageName());
int id_icon = getResources().getIdentifier(menuItemsIcons[ress], "drawable", this.getPackageName());
NsMenuItemModel mItem = new NsMenuItemModel(id_title, id_icon);
// if (res==1) mItem.counter=12; //it is just an example...
// if (res==3) mItem.counter=3; //it is just an example...
mAdapter.addItem(mItem);
res++;
}
mDrawerList = (ListView) findViewById(R.id.drawer);
if (mDrawerList != null)
mDrawerList.setAdapter(mAdapter);
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
}
#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);
mDrawerToggle.onConfigurationChanged(newConfig);
}
#Override
public boolean onOptionsItemSelected(MenuItem item)
{
/*
* The action bar home/up should open or close the drawer.
* ActionBarDrawerToggle will take care of this.
*/
if (mDrawerToggle.onOptionsItemSelected(item))
{
return true;
}
// Handle your other action bar items...
return super.onOptionsItemSelected(item);
}
private class CustomActionBarDrawerToggle extends ActionBarDrawerToggle
{
public CustomActionBarDrawerToggle(Activity mActivity, DrawerLayout mDrawerLayout)
{
super(mActivity, mDrawerLayout, R.drawable.ic_drawer, R.string.ns_menu_open, R.string.ns_menu_close);
}
#Override
public void onDrawerClosed(View view)
{
getSupportActionBar().setTitle(getString(R.string.ns_menu_close));
supportInvalidateOptionsMenu(); // creates call to
// onPrepareOptionsMenu()
}
#Override
public void onDrawerOpened(View drawerView)
{
getSupportActionBar().setTitle(getString(R.string.ns_menu_open));
supportInvalidateOptionsMenu(); // creates call to
// onPrepareOptionsMenu()
}
}
private class DrawerItemClickListener implements ListView.OnItemClickListener
{
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
mDrawer.closeDrawer(mDrawerList);
switch (position)
{
case 1:
Intent a = new Intent(MainActivity.this, Home.class);
startActivity(a);
break;
case 2:
Intent ac = new Intent(MainActivity.this, ConnectionListActivity.class);
startActivity(ac);
break;
default:
}
}
EDIT
I need to Extend it.Because the MainActivity has the navigation drawer.Now ConnectionEditActivity
doesn't shows the navigationDrawer nor the ActionBar .But i need to show the ActionBar
Any Suggestions ??

In Java you can't extend multiple classes, and for a good reason. Take for example what you are trying to accomplish by extending MainActivity and ListActivity. In your new class, when you call:
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
...
}
Which onCreate() are you overriding? The one from ListActivity, or the one from MainActivity?
What the link you posted is saying is that instead of inheriting from another object, you compose your new object of the one you are trying to use. For example:
public class NewClass extends OldClass1 {
private OldClass2 mOldClass2 = new OldClass2();
#Override
public methodFromOldClass1() {
}
public methodFromOldClass2() {
mOldClass2.methodFromOldClass2();
}
}
The problem with this approach is that the methods from MainActivity and ListActivity are still going to have the same name, which although you can work around, it will become a headache quickly.
So the problem is a result of how you designed your class hierarchy. You will need to think about what functions you need from MainActivity, and what functions from ListActivity and choose how to reimplement your objects.
My Suggestion, since ListActivity only makes it slightly easier to work with lists (not that much easier) you can just skip it and implement the code related to the list on your own, and that way you can just extend MainActivity

You need to start by identifying what parts of MainActivity you need to inherit from, and what do you need from ListActivity.
Then, you have various possibilities:
Trivially, not extending ListActivity. Extending ListActivity only provides you with utility methods to work with the ListView, but you can totally have a ListView in an Activity without it being a ListActivity.
Create a utility class that contains extracted methods you need from MainActivity and call these methods from both your new class and MainActivity.
Modify MainActivity so that it extends ListActivity. After all it does contain a ListView (you'd loose the ActionBar thing, though).

ActionBarCompat can't find methods from the superclass

I'm following a tutorial on ActionBarCompat that also enables a search text area. I extended the ActionBarActivity from the v7 support lib. When I try to override these two methods it can't find them in the superclass. I went to source and looked at the superclass' methods and I can't locate them there as well. The two methods are onQueryTextSubmit and onQueryTextChange
This was the tutorial.
Any idea what I am doing wrong?
This is the error when I hover over the methods:
The method onQueryTextChange(String) of type MainActivity must override or implement a supertype method
public class MainActivity extends ActionBarActivity{
private SearchView mSearchView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
ViewConfiguration config = ViewConfiguration.get(this);
Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");
if(menuKeyField != null) {
menuKeyField.setAccessible(true);
menuKeyField.setBoolean(config, false);
}
} catch (Exception ex) {
// Ignore
}
}
#Override
public boolean onQueryTextSubmit(String s) {
Toast.makeText(this, s, Toast.LENGTH_LONG).show();
return true;
}
#Override
public boolean onQueryTextChange(String s) {
return false;
}
#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);
MenuItem searchItem=menu.findItem(R.id.action_search);
mSearchView = (SearchView) MenuItemCompat.getActionView(searchItem);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()){
case R.id.action_search:
mSearchView.setIconified(false);
return true;
}
return false;
}

It sounds like you are not implementing the class that is needed for those methods.
public class MainActivity extends ActionBarActivity implements SearchView.OnQueryTextListener
Make sure that you implemented SearchView.OnQueryTextListener.

Where to declare onOptionsItemSelected for global use?

I'm very new to Android development.
In my MainActivity.java file, I've declared an onOptionsItemSelected(MenuItem menu) method that allows the user to jump between the current MainActivity.java page and another page I created called Settings.java.
When the user goes to the Settings.java page, and they click on the Home option from the menu, nothing happens. I know this is because the onOptionsItemSelected(MenuItem menu) is only defined in the MainActivity.java class and not in the Settings.java class.
I'm overcoming this right now by copying the onOptionsItemSelected(MenuItem menu) from MainActivity.java into Settings.java. But this is very redundant.
Where should I be declaring methods that could be reused in different classes?
MainActivity.java
public class MainActivity extends Activity {
...
#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;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_settings:
showMsg("Settings Clicked");
this.startActivity(new Intent(this, Settings.class));
return true;
case R.id.action_home:
showMsg("Home clicked");
this.startActivity(new Intent(this, MainActivity.class));
return true;
default:
return super.onOptionsItemSelected(item);
}
}
private void showMsg(String msg) {
Toast toast = Toast.makeText(this.getBaseContext(), msg, Toast.LENGTH_LONG);
toast.show();
}
}
Settings.java
public class Settings extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.settings);
}
#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) {
switch (item.getItemId()) {
case R.id.action_settings:
this.startActivity(new Intent(this, Settings.class));
return true;
case R.id.action_home:
this.startActivity(new Intent(this, MainActivity.class));
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}

If you create an Activity called BaseActivity that has your common onOptionsItemSelected() code then extend this class to create MainActivity and Settings both of these classes will use the super class' (i.e. BaseActivity's) onOptionsItemSelected().
Another approach is to switch to Fragments, since Fragments use the host Activity's onOptionsItemSelected() as well as their own. Both of these tactics allow you to use "centralized" code and not have to maintain multiple "cut and paste" copies.