java - android DialogFragment mDialog 为空导致异常

Question

我正在开发安卓纸牌游戏，我正在使用 DialogFragment 渲染一些图像并告诉玩家对对手采取行动。

下面的代码被执行了很多次，完全没有错误，但是在假设 5 到 10 次之后发生了以下异常。

E/AndroidRuntime: FATAL EXCEPTION: mainProcess: com.arabdealgame.arabdealgame, PID: 8359
                                                                             java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.Dialog.setOwnerActivity(android.app.Activity)' on a null object reference
                                                                                 at android.app.DialogFragment.onActivityCreated(DialogFragment.java:482)
                                                                                 at com.arabdealgame.activities.dialog.RentCardDialog.onActivityCreated(RentCardDialog.java:342)
                                                                                 at android.app.Fragment.performActivityCreated(Fragment.java:2362)
                                                                                 at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1014)
                                                                                 at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1171)
                                                                                 at android.app.BackStackRecord.run(BackStackRecord.java:815)
                                                                                 at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1578)
                                                                                 at android.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:563)
                                                                                 at com.arabdealgame.bo.Actions.RentActionCard$5.run(RentActionCard.java:315)
                                                                                 at android.os.Handler.handleCallback(Handler.java:751)
                                                                                 at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                 at android.os.Looper.loop(Looper.java:154)
                                                                                 at android.app.ActivityThread.main(ActivityThread.java:6077)
                                                                                 at java.lang.reflect.Method.invoke(Native Method)
                                                                                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
                                                                                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

上面的异常说明里面android.app.DialogFragment mDialog 在该行为空mDialog.setContentView(view);

android.app.DialogFragment

 public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        if (!mShowsDialog) {
            return;
        }

        View view = getView();
        if (view != null) {
            if (view.getParent() != null) {
                throw new IllegalStateException("DialogFragment can not be attached to a container view");
            }
            mDialog.setContentView(view);
        }
        mDialog.setOwnerActivity(getActivity());

我正在从这里实例化对话框错误发生在

boolean executePendingTransactions = fm.executePendingTransactions();我按照相关帖子中的建议添加了它以解决问题。在添加此语句之前，错误发生时没有说明我的包下的任何类

RentActionCard.java

 getActivity().runOnUiThread(new Runnable() {
            @Override
            public void run() {
                MyLog.i(TAG, "run: --------------------------1");
                FragmentManager fm = getActivity().getFragmentManager();
                MyLog.i(TAG, "run: --------------------------2");
                RentCardDialog rentCardDialog = new RentCardDialog();
                MyLog.i(TAG, "run: --------------------------3");
                if (!GameInfo.getCurrentPlayer().isUser()) {
                    MyLog.i(TAG, "run: --------------------------4");
                    rentCardDialog.setAgainstUser(true);
                }
                rentCardDialog.show(fm, "ccc");
                boolean executePendingTransactions = fm.executePendingTransactions();
                MyLog.d(TAG, "RentActionCard - executePendingTransactions : " + executePendingTransactions);
                MyLog.i(TAG, "run: --------------------------5");
            }
        });

为了在我的对话框中进行调试，此方法已被重写

@Override
    public void onActivityCreated(Bundle savedInstanceState) {
        MyLog.i(TAG, "onActivityCreated: ----------------------------------");
        super.onActivityCreated(savedInstanceState);
    }

Answer 1

通过执行以下操作不再显示此异常:

1. 我将所有组件声明为字段成员而不是局部变量

   public class RentCardDialog extends DialogFragment {
   
   private static final String TAG = "RentCardDialog";
   
   private TextView title1;
   private TextView title2;
   private TextView title1TxtView;
   private TextView title2TxtView;
   

2. 然后只需在 onCreateView 中初始化它们，如下所示

   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) {
   
   View rootView = inflater.inflate(R.layout.dialog_rent_card, container, false);
   
   title1 = (TextView) rootView.findViewById(R.id.rent_card_dialog_title1);
   title2 = (TextView) rootView.findViewById(R.id.rent_card_dialog_title2);
   title1TxtView = (TextView) rootView.findViewById(R.id.rent_card_dialog_title1);
   title2TxtView = (TextView) rootView.findViewById(R.id.rent_card_dialog_title2);
   

3. 最后，我添加了我想要的任何 fragment ，并按如下方式在 onActivityCreated 中构建所有对话框组件

    @Override  
    public void onActivityCreated(Bundle savedInstanceState) {
   
   super.onActivityCreated(savedInstanceState);  // Will now complete and not crash
   
   try {
       buildUserOptions();
       MyLog.i(TAG, "onCreateView: ---------------------------3");
   
       player2Fragment.setExecuteCallback(new CallbackInterface() {
           @Override
           public void execute() {
               player2Fragment.refreshPlayerData(player2);
           }
       });
   

在对话框的业务工作在 onCreateView 内部之前，所以问题可能是某些组件尚未真正加载，特别是 fragment ，因此它会触发该异常，

现在通过执行以下操作，它可以完美地工作。