Question

我遇到来自/发送到片段的通知有问题。我将尝试尽可能清楚地解释我的情景以显示问题。

我有一个活动，MyWorkout.java，这个活动有一个可扩展的列表视图。可扩展列表视图上的所有项目都将用户发送到第二个活动WorkoutDaysActivity。它们都发送了单独的额外意图，因此我知道用户点击了哪个项目。在WorkoutDaysActivity.java中，创建了3个片段，周一，周三和周五。我为每个活动都有单独的课程。这些类具有回收器视图和计时器。我知道，当计时器结束时，用户会收到通知。这有效，但是当我尝试将用户从通知发送到WorkoutDaysActivity时，它会因以下错误而崩溃。

    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.hashCode()' on a null object reference
                                                                                at com.bestworkouts.sheikoworkout.WorkoutDaysActivity.addPages(WorkoutDaysActivity.java:45)
                                                                                at com.bestworkouts.sheikoworkout.WorkoutDaysActivity.onCreate(WorkoutDaysActivity.java:29)

它发送给我的那一行是它试图根据MyWorkout.java传递的意图设置标题（下面的switch语句）。我猜这是因为当他们从通知而不是从MyWorkout.java到达这个类时没有传递意图，因此字符串标题为null。我的问题是我不知道如何解决这个问题。如果我将它发送到MyWorkout.java，通知工作正常，但我更愿意将其发送回设置定时器的位置。

public class WorkoutDaysActivity extends BaseActivity{

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.workout_days);
    mToolBar = activateToolbar();
    setUpNavigationDrawer();



    ViewPager vp = (ViewPager) findViewById(R.id.view_pager);
    this.addPages(vp);

    TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
    tabLayout.setupWithViewPager(vp);
    tabLayout.setOnTabSelectedListener(listener(vp));
}

//ADD ALL PAGES
private void addPages(ViewPager pager) {
    MyFragPagerAdapter adapter = new MyFragPagerAdapter(getSupportFragmentManager());
    Intent intent = getIntent();
    String workout = intent.getStringExtra("workout");
    Bundle args = new Bundle();
    args.putString("workout", workout);
    String title = args.getString("workout");
    switch(title) {
        case "w29w1" : {
            getSupportActionBar().setTitle("Workout 29 Week 1");
            break;
        }
        case "w29w2" : {
            getSupportActionBar().setTitle("Workout 29 Week 2");
            break;
        }
MondayFragment mondayFragment = new MondayFragment();
    mondayFragment.setArguments(args);
    adapter.addPage(mondayFragment);
    WedFragment wedFragment = new WedFragment();
    wedFragment.setArguments(args);
    adapter.addPage(wedFragment);
    FridayFragment fridayFragment = new FridayFragment();
    fridayFragment.setArguments(args);
    adapter.addPage(fridayFragment);
    pager.setAdapter(adapter);
}

这是计时器的位置（MondayFragment.java）：

private Button btnStart;
private Button btnStop;
private Button btnReset;
private CountDownTimer mCountDownTimer;
private TextView txtViewRest;

private void start() {
    mCountDownTimer = new CountDownTimer(5000, 1000) {
        @Override
        public void onTick(long millisUntilFinished) {
            txtViewRest.setText("Rest Remaining: " + millisUntilFinished / 1000 + " seconds.");
        }

        @Override
        public void onFinish() {
            txtViewRest.setText("Done!");
            showNotification();
        }
    }.start();
}
public void cancel() {
    if (mCountDownTimer != null) {
        mCountDownTimer.cancel();
        txtViewRest.setText("Rest Remaining: 5 seconds");
    } else return;
}
public void reset() {
    if (mCountDownTimer != null) {
        mCountDownTimer.cancel();
        txtViewRest.setText("Rest Remaining: 5 Seconds");
    } else return;
}

   public void showNotification() {
    NotificationCompat.Builder builder = new NotificationCompat.Builder(getContext());
    builder.setSmallIcon(R.drawable.sheikoicon);
    builder.setContentTitle("Sheiko Rest Timer");
    builder.setContentText("Rest timer is up, start your set!");
    builder.setDefaults(Notification.DEFAULT_SOUND|Notification.DEFAULT_VIBRATE);
    builder.setAutoCancel(true);
    Intent intent = new Intent(getActivity(), WorkoutDaysActivity.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    TaskStackBuilder stackBuilder = TaskStackBuilder.create(getContext());
    stackBuilder.addParentStack(WorkoutDaysActivity.class);
    stackBuilder.addNextIntent(intent);
    PendingIntent pendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_NO_CREATE);
    builder.setContentIntent(pendingIntent);
    NotificationManager NM = (NotificationManager) getActivity().getSystemService(Context.NOTIFICATION_SERVICE);
    NM.notify(0, builder.build());
}

  @Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    SharedPreferences pref = this.getActivity().getSharedPreferences("MyPref", 0);
   View view = inflater.inflate(R.layout.monday_fragment, null);

    txtViewRest = (TextView) view.findViewById(R.id.txtViewRest);
    btnStart = (Button) view.findViewById(R.id.btnStart);
    btnStop = (Button) view.findViewById(R.id.btnStop);
    btnReset = (Button) view.findViewById(R.id.btnReset);

    btnStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            start();
        }
    });
    btnStop.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            cancel();
        }
    });
    btnReset.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            reset();
        }
    });

非常感谢任何和所有帮助！

Answer 1

我设法解决了这个问题，我会在这里发布解决方案，以防将来有人遇到同样的问题。

这实际上是一个非常简单的修复，我所要做的只是将额外的意图放在通知代码中。

所以从MyWorkout.java我把这个意图传递给了WorkoutDaysActivity：

Intent intent = new Intent(getApplicationContext(), WorkoutDaysActivity.class);
                    intent.putExtra("workout", "w29w1");
                    startActivity(intent);

在锻炼日活动中，我有这个意图，并将其作为参数传递给所有三个片段，如下所示：

Intent intent = getIntent();
    String workout = intent.getStringExtra("workout");
    Bundle args = new Bundle();
    args.putString("workout", workout);

    MondayFragment mondayFragment = new MondayFragment();
    mondayFragment.setArguments(args);
    adapter.addPage(mondayFragment);
    WedFragment wedFragment = new WedFragment();
    wedFragment.setArguments(args);
    adapter.addPage(wedFragment);

然后在我发出通知的每个片段中，我必须添加intent.putExtra

public void showNotification() {
    NotificationCompat.Builder builder = new NotificationCompat.Builder(getContext());
    builder.setSmallIcon(R.drawable.sheikoicon);
    builder.setContentTitle("Rest Timer");
    builder.setContentText("Rest timer is up, start your set!");
    builder.setDefaults(Notification.DEFAULT_SOUND|Notification.DEFAULT_VIBRATE);
    builder.setAutoCancel(true);
    Intent intent = new Intent(getActivity(), WorkoutDaysActivity.class);
    intent.putExtra("workout", workout3);
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    TaskStackBuilder stackBuilder = TaskStackBuilder.create(getContext());
    stackBuilder.addParentStack(WorkoutDaysActivity.class);
    stackBuilder.addNextIntent(intent);
    PendingIntent pendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
    builder.setContentIntent(pendingIntent);
    NotificationManager NM = (NotificationManager) getActivity().getSystemService(Context.NOTIFICATION_SERVICE);
    NM.notify(0, builder.build());
}

其中，锻炼3是：

 args = getArguments();
    workout3 = args.getString("workout");

Android错误将从通知中分离出来

1 个答案: