Question

How would I implement a Buttonlistener for a second layout which is still be called in the main Acitivity?
I already tried it by a named Button listener and via an anonymous. But still get nullpointer Exceptions.

Code:

back = (Button) findViewById(R.id.backToMain);
 if(back != null)
    back.setOnClickListener( new View.OnClickListener() {
                public void onClick(View view) {
                    setLayout(R.layout.main);
                }
            });

Layout.xml

<Button android:layout_width="fill_parent" 
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:id="@+id/backToMain"
        android:text="Zurück">
    </Button>

Answer 1

Try this

Change the button attr tag

<Button android:layout_width="fill_parent" 
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:id="@+id/backToMain"
        android:text="Zurück"
        android:onClick="goBack">
    </Button>

In your activity create a method

public void goBack(View v) {
//Write code here
}