我在使以下代码正常工作时遇到问题。当我按下"图像"按钮时,应用程序会崩溃。有人能指出我下面的代码哪里出了问题吗?
public class training extends Fragment {
ImageButton run;
public training()
{
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
View rootView = inflater.inflate(R.layout.fragment_training, container, false);
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
run = (ImageButton) getActivity().findViewById
(R.id.StartRunClass);
run.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i= new Intent(getActivity(),Running.class);
getActivity().startActivity(i);
}
});
}
}
我在被点名的班级里只有
public class Running extends FragmentActivity
//implements LocationProvider.LocationCallback {
// private GoogleMap mMap; // Might be null if Google Play services APK is not available.
//public LocationProvider mLocationProvider;
{
ImageButton start, stop;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_run);
获取以下运行时错误
02-24 16:12:26.377 30732-30732/project.project E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at project.project.training.run(training.java:38)
at project.project.training.onCreateView(training.java:30)
at android.app.Fragment.performCreateView(Fragment.java:1695)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:885)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1057)
at android.app.BackStackRecord.run(BackStackRecord.java:694)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1435)
at android.app.FragmentManagerImpl$1.run(FragmentManager.java:441)
at android.os.Handler.handleCallback(Handler.java:800)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5392)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
我很确定问题出在getActivity()
返回null
。
覆盖OnAttach
并存储对附加活动的引用:
Activity activity;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
this.activity = activity;
}
用您的参考号替换getActivity()
:
@Override
public void onClick(View v) {
Intent i= new Intent(activity,Running.class);
activity.startActivity(i);
}
编辑
它崩溃是因为run
为null。我认为问题出在你使用findViewByID
:的方式上
run = (ImageButton) getActivity().findViewById(R.id.StartRunClass);
您应该在onCreateView
上执行此操作,并使用rootView
而不是getActivity
:
View rootView = inflater.inflate(R.layout.fragment_training, container, false);
run = (ImageButton) rootView.findViewById(R.id.StartRunClass);
如果它仍然崩溃,请检查fragment_training
布局以确保它包含一个名为StartRunClass
的ImageView。