当我通过 App-Change 按钮再次打开已关闭的应用程序时,我收到此错误消息:
Caused by: java.lang.InstantiationException: can't instantiate class com.*.FragmentContact$1; no empty constructor
我发现了一些关于内部类的技巧,并使它们成为静态等。但是这个 FragmentContact 是*.java 文件中的一个公共类,并且有一个公共的空构造函数。我在这个项目中使用 Google Maps Api v2 并从互联网的某个地方做一个技巧来设置我的 MapView。看这里:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_contact, null);
try {
MapsInitializer.initialize(this.getActivity().getApplicationContext());
} catch (GooglePlayServicesNotAvailableException e) {
e.printStackTrace();
}
fragment = new SupportMapFragment() {
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mMap = fragment.getMap();
if (mMap != null) {
setupMap();
}
}
};
getFragmentManager().beginTransaction().replace(R.id.fragment_orte_map_parent, fragment).commit();
return v;
}
当我把这个 MapView 东西剪掉时,一切正常。也许有人可以解释我做错了什么。
我完整的堆栈跟踪:
FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.*/com.*.MainActivity}: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment com.*.FragmentContact$1: make sure class name exists, is public, and has an empty constructor that is public
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2357)
at android.app.ActivityThread.access$600(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5226)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment com.*.FragmentContact$1: make sure class name exists, is public, and has an empty constructor that is public
at android.support.v4.app.Fragment.instantiate(Fragment.java:405)
at android.support.v4.app.FragmentState.instantiate(Fragment.java:97)
at android.support.v4.app.FragmentManagerImpl.restoreAllState(FragmentManager.java:1767)
at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:208)
at com.*.MainActivity.onCreate(MainActivity.java:20)
at android.app.Activity.performCreate(Activity.java:5104)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2261)
... 11 more
Caused by: java.lang.InstantiationException: can't instantiate class com.*.FragmentContact$1; no empty constructor
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1319)
at android.support.v4.app.Fragment.instantiate(Fragment.java:394)
... 18 more