how to set imagebutton resource using a for loop Android

Try the below. You have not initialized ImageButton

   ImageButton b[];    

In your onnCreate(param)

  b = new ImageButton[15]; 
  for (int i = 0 ; i <15; i++){
    b[i] = new ImageButton(ActiivtyName.this);
    b[i].setImageResource(R.drawable.playzz);        
}

Also remember to add the button to you root view of the layout.

Example:

You can also set the layout programatically. You can use use linear layout or relative layout set the layout parameters. Add the Imagebuttons to the layout and set the content to the activity.

Modify the below according to your requirements.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView
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">
<LinearLayout 
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
android:id="@+id/ll"
tools:context=".MainActivity" >
</LinearLayout> 
</ScrollView>

MainActivity.java

public class MainActivity extends Activity {   
ImageButton b[]; 
LinearLayout ll;
protected void onCreate(Bundle savedInstanceState) {   
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ll = (LinearLayout) findViewById(R.id.ll);// initialize linearlayout           
    setresource();
}
public void setresource()
{
       b = new ImageButton[15];
       for (int i = 0 ; i < 15; i++){
        b[i]= new ImageButton(MainActivity.this); // initilize
        b[i].setMaxWidth(40); // set the maxwidth
        b[i].setImageResource(R.drawable.ic_launcher); // set background image
        ll.addView(b[i]); // add the imagebutton to the linearlayout
       }
  }
}