Question

在与片段进行通信时，我得到致命异常。

此应用程序的主要功能是

1）主要活动包含两个片段A＆amp;乙

2）片段A包含一个按钮

3）片段B包含一个TextView。

4）如果我点击FrgamentA中的按钮计数器应该增加，这将显示在片段B中

例外如下::

04-29 08:08:29.234: E/AndroidRuntime(1289): FATAL EXCEPTION: main
04-29 08:08:29.234: E/AndroidRuntime(1289): Process: com.example.fragmentscommunication, PID: 1289
04-29 08:08:29.234: E/AndroidRuntime(1289): java.lang.NullPointerException
04-29 08:08:29.234: E/AndroidRuntime(1289):     at com.example.fragmentscommunication.FragmentA.onClick(FragmentA.java:37)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at android.view.View.performClick(View.java:4438)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at android.view.View$PerformClick.run(View.java:18422)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at android.os.Handler.handleCallback(Handler.java:733)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at android.os.Handler.dispatchMessage(Handler.java:95)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at android.os.Looper.loop(Looper.java:136)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at java.lang.reflect.Method.invokeNative(Native Method)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at java.lang.reflect.Method.invoke(Method.java:515)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-29 08:08:29.234: E/AndroidRuntime(1289):     at dalvik.system.NativeStart.main(Native Method)

我的java代码是

MainActivity.java

public class MainActivity extends ActionBarActivity implements communicator{

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

@Override
public void respond(String str) {
    // TODO Auto-generated method stub

    FragmentManager fm = getFragmentManager();
    FragmentB fB = (FragmentB) fm.findFragmentById(R.id.fragment2);
    fB.setText(str);

}

}

FragmentA.java

public class FragmentA extends Fragment implements OnClickListener{

Button bt;
int counter = 0;
communicator comm;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    return inflater.inflate(R.layout.fragment_a, container,false);
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onActivityCreated(savedInstanceState);

    bt=(Button) getActivity().findViewById(R.id.button1);
    bt.setOnClickListener(this);
}

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

    counter++;
    comm.respond("Button was clicked "+counter +"times");
}

}

FragmentB.java

public class FragmentB extends Fragment{

TextView tv;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    return inflater.inflate(R.layout.fragment_b, container,false);
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onActivityCreated(savedInstanceState);
    tv = (TextView) getActivity().findViewById(R.id.textView1);
}

public void setText(String data)
{
    tv.setText(data);
}

}

Answer 1

尝试以下代码： -

public class FragmentA extends Fragment implements OnClickListener{

Button bt;
int counter = 0;
communicator comm;
View view;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    view =  inflater.inflate(R.layout.fragment_a, container,false);

    return view;
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onActivityCreated(savedInstanceState);
    tv = (TextView) view.findViewById(R.id.textView1);
}
@Override
public void onClick(View v) {
    // TODO Auto-generated method stub

    counter++;
    comm.respond("Button was clicked "+counter +"times");
}

}

错误，因为您正在使用片段视图而未获取片段视图。

片段传播中的致命异常

1 个答案: