问继承-方法崩溃的android开发

EN

package de.basti12354.tage.uebungen;


import com.example.bikinifigur2.R;

import android.app.Activity;


 public class Oberklasse extends Activity {


public void crunch() {
    setContentView(R.layout.crunch);
}


public void Crunch(int anzahl) {
     setContentView(R.layout.crunch);
}

}

 package de.basti12354.tage.uebungen;



 import com.example.bikinifigur2.R;

 import android.app.Activity;
 import android.os.Bundle;
 import android.support.v7.app.ActionBarActivity;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;

 public class Tag1 extends Oberklasse implements OnClickListener {

public Button btn;
Oberklasse neu = new Oberklasse();

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.tt1);


    //getActionBar().setTitle("Trainingstag 1");
    //getActionBar().setDisplayHomeAsUpEnabled(true);   


    //Button finden und Initialisieren!
    btn = (Button) findViewById(R.id.trainingsstart);
    btn.setOnClickListener(this);



}

@Override
public void onClick(View v) {
    // TODO Auto-generated method stub

    neu.crunch();

}

 }

 03-20 11:50:11.956: E/AndroidRuntime(2017): FATAL EXCEPTION: main
 03-20 11:50:11.956: E/AndroidRuntime(2017): java.lang.NullPointerException
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at android.app.Activity.setContentView(Activity.java:1895)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at de.basti12354.tage.uebungen.Oberklasse.crunch(Oberklasse.java:13)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at de.basti12354.tage.uebungen.Tag1.onClick(Tag1.java:41)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at android.view.View.performClick(View.java:4240)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at android.view.View$PerformClick.run(View.java:17721)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at android.os.Handler.handleCallback(Handler.java:730)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at android.os.Handler.dispatchMessage(Handler.java:92)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at android.os.Looper.loop(Looper.java:137)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at android.app.ActivityThread.main(ActivityThread.java:5103)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at java.lang.reflect.Method.invokeNative(Native Method)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at java.lang.reflect.Method.invoke(Method.java:525)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
 03-20 11:50:11.956: E/AndroidRuntime(2017):    at dalvik.system.NativeStart.main(Native Method)

<Button
    android:id="@+id/trainingsstart"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="115dp"
    android:text="@string/trainingstart" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="58dp"
    android:text="TextView" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="17dp"
    android:text="@string/heutigeuebungen"
    android:textAppearance="?android:attr/textAppearanceLarge" />

 </RelativeLayout>