“specified child already has a parent” error
Sorry to make another topic on this subjcet but I've already read several of them and still don't know why I'm getting this error. I followed the "Building Your First App" tutorial on <http://developer.android.com/training/basics/firstapp/index.html> and then tried to modify my application to give a layout to DisplayMessageActivity Class. I've created a file called "activity_displaymessage.xml" and implemented it to the class.

I'm new to android and I'm trying to understand how this all works. What am I doing wrong?

Here is my code:

MainActivity.java

    public class MainActivity extends Activity {
    
    	public final static String EXTRA_MESSAGE = "com.example.sampleandroid.MESSAGE";
    	
            .
            .
            .
    
        
        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);
        }
    }

DisplayMessageActivity.java

    public class DisplayMessageActivity extends Activity {
    
    	@Override
    	public void onCreate(Bundle savedInstanceState){
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_displaymessage);
    		
    		Intent intent = getIntent();
    		String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
    		
    		TextView textview = (TextView) findViewById(R.id.text_view);
    		textview.setText(message);
    		
    		setContentView(textview);
    	}
    }

activity_displaymessage.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:orientation="horizontal"
        android:weightSum="2">
        
        <TextView android:id="@+id/text_view"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:textSize="30sp"/>
        
    </LinearLayout>
“specified child already has a parent” error
===

Sorry to make another topic on this subjcet but I've already read several of them and still don't know why I'm getting this error. I followed the "Building Your First App" tutorial on <http://developer.android.com/training/basics/firstapp/index.html> and then tried to modify my application to give a layout to DisplayMessageActivity Class. I've created a file called "activity_displaymessage.xml" and implemented it to the class.

I'm new to android and I'm trying to understand how this all works. What am I doing wrong?

Here is my code:

MainActivity.java

    public class MainActivity extends Activity {
    
    	public final static String EXTRA_MESSAGE = "com.example.sampleandroid.MESSAGE";
    	
            .
            .
            .
    
        
        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);
        }
    }

DisplayMessageActivity.java

    public class DisplayMessageActivity extends Activity {
    
    	@Override
    	public void onCreate(Bundle savedInstanceState){
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_displaymessage);
    		
    		Intent intent = getIntent();
    		String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
    		
    		TextView textview = (TextView) findViewById(R.id.text_view);
    		textview.setText(message);
    		
    		setContentView(textview);
    	}
    }

activity_displaymessage.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:orientation="horizontal"
        android:weightSum="2">
        
        <TextView android:id="@+id/text_view"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:textSize="30sp"/>
        
    </LinearLayout>