在活动中通过onclicklistener切换片段

Question

public class StartActivity extends Activity {

    public static Context appContext;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //Fragment
        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction =
            fragmentManager.beginTransaction();

        MeinFragment A_fragment = new MeinFragment();
        fragmentTransaction.replace(android.R.id.content, A_fragment);

        fragmentTransaction.commit();

        ImageButton BTN1 = (ImageButton) findViewById(R.id.leftButton);
        BTN1.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                SearchFragment A_fragment = new SearchFragment();
                fragmentTransaction.replace(android.R.id.content, A_fragment);

            }
        }); 
    }
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    FragmentManager fragmentManager = getFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();


    MeinFragment A_fragment = new MeinFragment();


    fragmentTransaction.replace(android.R.id.content, A_fragment);

    fragmentTransaction.commit();


  //Fragments changing
    ImageButton BTN1 = (ImageButton) findViewById(R.id.leftButton);
   BTN1.setOnClickListener(new OnClickListener() {
       public void onClick(View v) {



          FragmentManager fragmentManager = getFragmentManager();
            FragmentTransaction fragmentTransaction =                        fragmentManager.beginTransaction();


          SearchFragment B_fragment = new SearchFragment();
            fragmentTransaction.replace(android.R.id.content, B_fragment);
            fragmentTransaction.commit();

       }
       });

}

和logcat：

Answer 1

fragmentTransaction
    .beginTransaction()
    .replace(android.R.id.content, A_fragment)
    .commit();