我在活动的onCreate中实现了一个Map Support片段，如下所示：
mMapFragment = new DRPCustomMapFragment() {
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
_map = mMapFragment.getMap();
setUpMapUI();
}
};
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fm.beginTransaction();
fragmentTransaction.replace(R.id.mapContainer, mMapFragment);
fragmentTransaction.commit();
fm.executePendingTransactions();
实际的CustomMapFragment类如下所示：
public class DRPCustomMapFragment extends SupportMapFragment {
private View mOriginalView;
private DRPMapWrapperLayout mMapWrapperLayout;
public DRPCustomMapFragment(){
}
public void onCreate(Bundle savedInstanceState) {
setRetainInstance(true);
super.onCreate(savedInstanceState);
}
@Override
public void onDestroyView() {
super.onDestroyView();
try {
SupportMapFragment fragment = (SupportMapFragment) getActivity()
.getSupportFragmentManager().findFragmentById(
R.id.map);
if (fragment != null) getFragmentManager().beginTransaction().remove(fragment).commit();
} catch (IllegalStateException e) {
//handle this situation because you are necessary will get
//an exception here :-(
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
mOriginalView = super.onCreateView(inflater, container, savedInstanceState);
mMapWrapperLayout = new DRPMapWrapperLayout(getActivity());
mMapWrapperLayout.addView(mOriginalView);
return mMapWrapperLayout;
}
@Override
public View getView() {
return mOriginalView;
}
public void setOnDragListener(DRPMapWrapperLayout.OnDragListener onDragListener) {
mMapWrapperLayout.setOnDragListener(onDragListener);
}
}
当我从开发人员选项中打开“不要保留活动”，以测试保存的实例状态包时，出现错误：
> 04-25 07:35:31.362: E/AndroidRuntime(19210):
> java.lang.RuntimeException: Unable to start activity
> ComponentInfo{com.sdsd.inhouse.drop/com.sdsd.inhouse.drop.activities.DRPCreateDropActivity}:
> android.support.v4.app.Fragment$InstantiationException: Unable to
> instantiate fragment
> com.sdsd.inhouse.drop.activities.DRPCreateDropActivity$5: make sure
> class name exists, is public, and has an empty constructor that is
> public 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.app.ActivityThread.access$800(ActivityThread.java:135) 04-25
> 07:35:31.362: E/AndroidRuntime(19210): at
> android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.os.Handler.dispatchMessage(Handler.java:102) 04-25
> 07:35:31.362: E/AndroidRuntime(19210): at
> android.os.Looper.loop(Looper.java:136) 04-25 07:35:31.362:
> E/AndroidRuntime(19210): at
> android.app.ActivityThread.main(ActivityThread.java:5017) 04-25
> 07:35:31.362: E/AndroidRuntime(19210): at
> java.lang.reflect.Method.invokeNative(Native Method) 04-25
> 07:35:31.362: E/AndroidRuntime(19210): at
> java.lang.reflect.Method.invoke(Method.java:515) 04-25 07:35:31.362:
> E/AndroidRuntime(19210): at
> com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 04-25
> 07:35:31.362: E/AndroidRuntime(19210): at
> dalvik.system.NativeStart.main(Native Method) 04-25 07:35:31.362:
> E/AndroidRuntime(19210): Caused by:
> android.support.v4.app.Fragment$InstantiationException: Unable to
> instantiate fragment
> com.sdsd.inhouse.drop.activities.DRPCreateDropActivity$5: make sure
> class name exists, is public, and has an empty constructor that is
> public 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.support.v4.app.Fragment.instantiate(Fragment.java:413) 04-25
> 07:35:31.362: E/AndroidRuntime(19210): at
> android.support.v4.app.FragmentState.instantiate(Fragment.java:97)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.support.v4.app.FragmentManagerImpl.restoreAllState(FragmentManager.java:1790)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:213)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> com.sdsd.inhouse.drop.activities.DRPCreateDropActivity.onCreate(DRPCreateDropActivity.java:183)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.app.Activity.performCreate(Activity.java:5231) 04-25
> 07:35:31.362: E/AndroidRuntime(19210): at
> android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
> 04-25 07:35:31.362: E/AndroidRuntime(19210): ... 11 more 04-25
> 07:35:31.362: E/AndroidRuntime(19210): Caused by:
> java.lang.InstantiationException: can't instantiate class
> com.sdsd.inhouse.drop.activities.DRPCreateDropActivity$5; no empty
> constructor 04-25 07:35:31.362: E/AndroidRuntime(19210): at
> java.lang.Class.newInstanceImpl(Native Method) 04-25 07:35:31.362:
> E/AndroidRuntime(19210): at
> java.lang.Class.newInstance(Class.java:1208) 04-25 07:35:31.362:
> E/AndroidRuntime(19210): at
> android.support.v4.app.Fragment.instantiate(Fragment.java:402) 04-25
> 07:35:31.362: E/AndroidRuntime(19210): ... 18 more
我看到了有关此here的另一篇文章，但坦率地说，我不明白解决方案是什么
最佳答案
解决方案是创建一个真实的子类。
语法new DRPCustomMapFragment() { // stuff }创建一个扩展DRPCustomMapFragment的匿名内部类。它没有构造函数，更不用说公共零参数了。
所以：
创建扩展AnotherDRPCustomMapFragment的DRPCustomMapFragment，将您的逻辑从您的匿名内部类移到那里。
从DRPCustomMapFragment中删除零参数构造函数，或者至少从中调用super()。
将AnotherDRPCustomMapFragment用作您的mMapFragment数据成员。
关于android - map 支持上没有空的构造函数错误，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/23292203/