Question

所以我正在编写一个名为摇滚，纸张，剪刀的游戏，每当我试图提示用户遇到困难时，我都会收到NullPointerException。我的目的是通过意图的putExtra方法启动一个通过难度值的新活动。此操作将通过自定义对话框执行。这是日志：

08-11 13:38:09.619    8725-8725/dserov.rockpaperscissors E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: dserov.rockpaperscissors, PID: 8725
java.lang.NullPointerException
        at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
        at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
        at android.widget.AbsListView.obtainView(AbsListView.java:2255)
        at android.widget.ListView.measureHeightOfChildren(ListView.java:1263)
        at android.widget.ListView.onMeasure(ListView.java:1175)
        at android.view.View.measure(View.java:16497)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
        at android.view.View.measure(View.java:16497)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
        at android.view.View.measure(View.java:16497)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at android.view.View.measure(View.java:16497)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at android.view.View.measure(View.java:16497)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
        at android.view.View.measure(View.java:16497)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1912)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1084)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1291)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5600)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
        at android.view.Choreographer.doCallbacks(Choreographer.java:574)
        at android.view.Choreographer.doFrame(Choreographer.java:544)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5001)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
        at dalvik.system.NativeStart.main(Native Method)

这是MainActivity：

public class MainActivity extends AppCompatActivity {

@Bind(R.id.singleplayerButton) Button mSingleplayerButton;
@Bind(R.id.multiplayerButton) Button mMultiplayerButton;
@Bind(R.id.gameEmblem) ImageView mGameEmblem;

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

    ButterKnife.bind(this);
    View.OnClickListener listener = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            switch (v.getId()) {
                case (R.id.singleplayerButton) : {
                    AlertDialogFragment dialog = new AlertDialogFragment();
                    dialog.show(getFragmentManager(), getString(R.string.difficulty_dialog));
                    break;
                }

                case (R.id.multiplayerButton) : {
                    break;
                }

            }
        }
    };

    mSingleplayerButton.setOnClickListener(listener);
    mMultiplayerButton.setOnClickListener(listener);
}

这是AlertDialogFragment：

public class AlertDialogFragment extends DialogFragment {
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final Context context = getActivity();
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        builder.setTitle(R.string.difficulty_prompt)
            .setItems(R.array.difficulties, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    Intent intent = new Intent(context, PlayActivity.class);
                    switch (which) {
                        case 0 : {
                            intent.putExtra(context.getString(R.string.difficulty_label), 0);
                            break;
                        }
                        case 1 : {
                            intent.putExtra(context.getString(R.string.difficulty_label), 1);
                            break;
                        }
                    }
                    startActivity(intent);
                }
            });
    AlertDialog dialog = builder.create();
    return dialog;
    }
}

Android Studio的bugtracker功能不会产生任何结果，只要按下Singleplayer按钮，就会通过某些系统功能抛出异常。在我获得异常的代码行之后没有任何线索，但我最好的猜测是AlertDialogFragment的show（）方法。

Answer 1

什么时候粉碎？在你的代码中，我没有看到你关闭对话框的行，所以如果你没有那行，并且在对话框显示后应用程序崩溃，并且在重定向到另一个活动之前尝试解除对话框

Answer 2

我一直在试图弄清楚它，我终于明白错误是什么。将.setItems(context.getResources().getStringArray(R.array.difficulties) ...更改为{{1}}就可以了。

显示AlertDialogFragment会导致NullPointerException

2 个答案: