尝试从类

Question

我建了一个闹钟，我有一个待释放的内容，应该打瞌睡闹钟。当它在Activity中时，相同的代码工作得很好。我改变了一些东西，现在它改变了一个不同的类。我得到一个nullpointerExecption。 （承包商从活动中获取背景信息。

延后功能：

public void settingNewIntentForSnooze() {
    PendingIntent alarmPendingIntent=null;
    Calendar calendar = Calendar.getInstance();
    // new alarm after the snooze.
    calendar.set(Calendar.MINUTE, calendar.get(Calendar.MINUTE) + snoozeTime);
    Intent snoozeIntent = new Intent(context, Alarm_Reciver.class);
    snoozeIntent.putExtra("click_status", true);
    //add that to try to solve the problem...
    snoozeIntent.setAction("Snooze");
    alarmPendingIntent = PendingIntent.getBroadcast(context, 0, snoozeIntent, alarmPendingIntent.FLAG_ONE_SHOT);
    //tells to phone to set the alarm
    alarm_manager.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), alarmPendingIntent);
}

AlarmPage活动（创建变量的代码）：

snooze= new Snooze(this,alarm_manager);

AlarmReciver：

public void onReceive(Context context, Intent intent) {
    Log.e("in alarm reciver","in alarm reciver");
    Intent service_intent= new Intent(context, RingtonePlayingService.class);//intent for the service ringtone playing
    boolean button_status = intent.getExtras().getBoolean("click_status");
    service_intent.putExtra("click_status", button_status);//passing button status
    context.startService(service_intent);//start the ringtone service
}

错误：

09-17 18:25:25.564 1563-1563/com.example.itay.newfrindlyalarm E/AndroidRuntime: FATAL EXCEPTION: main
                                                                            Process: com.example.itay.newfrindlyalarm, PID: 1563
                                                                            java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.AlarmManager.set(int, long, android.app.PendingIntent)' on a null object reference
                                                                                at com.example.itay.newfrindlyalarm.Snooze.settingNewIntentForSnooze(Snooze.java:60)
                                                                                at com.example.itay.newfrindlyalarm.Snooze.operate(Snooze.java:44)
                                                                                at com.example.itay.newfrindlyalarm.AlarmPage.operateSnooze(AlarmPage.java:88)
                                                                                at com.example.itay.newfrindlyalarm.AlarmPage$3.onClick(AlarmPage.java:68)
                                                                                at android.view.View.performClick(View.java:6256)
                                                                                at android.view.View$PerformClick.run(View.java:24697)
                                                                                at android.os.Handler.handleCallback(Handler.java:789)
                                                                                at android.os.Handler.dispatchMessage(Handler.java:98)
                                                                                at android.os.Looper.loop(Looper.java:164)
                                                                                at android.app.ActivityThread.main(ActivityThread.java:6541)
                                                                                at java.lang.reflect.Method.invoke(Native Method)
                                                                                at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                                                                                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
enter code here

Answer 1

根据错误消息判断alarm_manager null是否可能是AlarmManager？如果正确初始化TextView tv; Calendar mCurrentDate; int day, month, year; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_tuto4); tv = (TextView) findViewById(R.id.datePicker); mCurrentDate = Calendar.getInstance(); day = mCurrentDate.get(Calendar.DAY_OF_MONTH); month = mCurrentDate.get(Calendar.MONTH); year = mCurrentDate.get(Calendar.YEAR); month = month + 1; tv.setText(day+"/"+month+"/"+year); tv.setOnClickListener(new View.OnClickListener() { @Override public void onClick (View v) { final Calendar calendar = Calendar.getInstance(); int yy = calendar.get(Calendar.YEAR); int mm = calendar.get(Calendar.MONTH); int dd = calendar.get(Calendar.DAY_OF_MONTH); DatePickerDialog datePicker = new DatePickerDialog(Tuto4Activity.this, new DatePickerDialog.OnDateSetListener() { @Override public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) { String date = "Date"+String.valueOf(year) +"-"+String.valueOf(monthOfYear) +"-"+String.valueOf(dayOfMonth); tv.setText(date); tv.setText(date); } }, yy, mm, dd); datePicker.show(); } }); } public void onRadioButtonClicked(View view) { boolean checked = ( (RadioButton) view). isChecked(); switch (view.getId()) { case R.id.radioButton1: if (checked) setContentView(R.layout.activity_tuto2); break; case R.id.radioButton2: if (checked) setContentView(R.layout.activity_tuto3); break; case R.id.radioButton3: if (checked) setContentView(R.layout.activity_tuto4); break; } } } ，错误是否会消失？