Open an app will flash back

Recent study android, here there is a small problem, open the application on the flash back what is the reason?

 
package com.example.linearlayouttest; 



import android.os.Bundle; 
import android.app.Activity; 
import android.view.Menu; 
import android.widget.Button; 
import android.widget.LinearLayout; 

public class LinearLayoutTest extends Activity {

@ Override 
protected void onCreate (Bundle savedInstanceState) {
super.onCreate (savedInstanceState); 
setContentView (R.layout.activity_linear_layout_test); 
LinearLayout root = (LinearLayout) findViewById (R.id.root); 
Button bn1 = (Button) findViewById (R.id.bn1); 
bn1.setText (R.string.bn1); 
root.addView (bn1); 
Button bn2 = (Button) findViewById (R.id.bn2); 
bn2.setText (R.string.bn2); 
root.addView (bn2); 
} 

@ Override 
public boolean onCreateOptionsMenu (Menu menu) {
/ / Inflate the menu; this adds items to the action bar if it is present 
.getMenuInflater () inflate (R.menu.linear_layout_test, menu);. 
return true; 
} 

} 

 
xmlns: tools = "http://schemas.android.com/tools" 
android: layout_width = "match_parent" 
android: layout_height = "match_parent" 
android: orientation = "vertical" 
android: gravity = "bottom | center_horizontal" 
android: id = "@ + id / root" 
> 

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Reply:
The error message posted about ah
Reply:

 LinearLayout root = (LinearLayout) findViewById (R.id.root); 
root.addView (bn1); 
root.addView (bn2); 

More than three commented
Reply:
You can use the software to repair it
Reply:

reference to the second floor hjywyj reply:

 LinearLayout root = (LinearLayout) findViewById (R.id.root); 
root.addView (bn1); 
root.addView (bn2); 

The above three commented

Oh ah, because if directly in java in a direct new components only need addView eh?
Reply:

references, 4th Floor kaitankedemao reply:

Quote: references to the second floor hjywyj reply:

 LinearLayout root = (LinearLayout) findViewById (R.id.root); 
root.addView (bn1); 
root.addView (bn2); 

The above three commented

Oh ah, because if directly in java in a direct new components only need addView eh?

2nd Floor positive solution, addView belong to dynamic loading, and
setContentView (R.layout.activity_linear_layout_test); has a static loaded.
That is, the control has a static load, and there is no need static loading.
Reply:

The reply was deleted administrator at 2013-11-25 10:02:11

Reply:
Layout can not be achieved dynamically modify
root.addView (bn1);

Reply:
Can be dynamically loaded, but you have to re-set a btn the id, otherwise it will error