android - 从 PendingIntent.getActivity Android 获取空指针异常

Question

我正在尝试从按钮的 onClick 中添加一个未决 Intent 以实现警报，但我在“android:app.PendingIntent.getActivity(PendingIntent.java:257)”和“at android:app”处收到空指针异常.PendingIntent.getActivity(PendingIntent.java:224)”。

这是我的代码，点击“添加”按钮应该会创建待处理的 Intent。

public class DisplayAlertMessage extends Activity {
private int mYear, mMonth, mDay, mHour, mMinute;
private long alarm_time;
    private int rem = 0;
    private String date,time;
    private String lists1[] = new String[10];
static final int DATE_DIALOG_ID = 999;

@SuppressLint("InflateParams") 
public void displayAlertDialog(LayoutInflater inflater,final MainActivity obj,final MainActivity obj1,final Context con) {
    /** This intent invokes the activity DemoActivity, which in turn opens the AlertDialog window */
    final Intent in = new Intent("com.example.todotry_1.demoactivity");
     final View alertLayout = inflater.inflate(R.layout.layout_custom_dialog, null);
     final EditText Note = (EditText) alertLayout.findViewById(R.id.Note);
     final EditText Lists = (EditText) alertLayout.findViewById(R.id.Lists);
     final TextView Remind = (TextView) alertLayout.findViewById(R.id.Remind);
     final TextView Time = (TextView) alertLayout.findViewById(R.id.Time);
     final TextView Date = (TextView) alertLayout.findViewById(R.id.Date);
     final TextView Timeval = (TextView) alertLayout.findViewById(R.id.Timeval);
     final TextView Dateval = (TextView) alertLayout.findViewById(R.id.Dateval);
     final ImageView iv=(ImageView) alertLayout.findViewById(R.id.img);
     i=iv;
     AlertDialog.Builder alert = new AlertDialog.Builder(obj,R.style.DialogTheme);
     Remind.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               Log.d("onCLICK","REMIND");
               Toast.makeText(con, "REMIND CLICKED", Toast.LENGTH_SHORT).show();
               Remind.setVisibility(View.GONE);
               Time.setVisibility(View.VISIBLE);
               Date.setVisibility(View.VISIBLE);
               rem = 1;
               Time.setOnClickListener(new OnClickListener() {
                @Override
                            public void onClick(View v) {
                            final Calendar c = Calendar.getInstance();
                                mHour = c.get(Calendar.HOUR_OF_DAY);
                                mMinute = c.get(Calendar.MINUTE);

                                // Launch Time Picker Dialog
                                TimePickerDialog tpd = new TimePickerDialog(obj,new TimePickerDialog.OnTimeSetListener() 
                                {

                                            @Override
                                            public void onTimeSet(TimePicker view, int hourOfDay,int minute) {
                                             // Display Selected time in textbox
                                            Timeval.setVisibility(View.VISIBLE);
                                                Timeval.setText(hourOfDay + ":" + minute);
                                            }
                                        }, mHour, mMinute, false);
                                    tpd.show();
                                    time = mHour+":"+mMinute;
                            }
                    });
               Date.setOnClickListener(new OnClickListener() {
                            @Override
                            public void onClick(View v) {
                            final Calendar c = Calendar.getInstance();
                                mYear = c.get(Calendar.YEAR);
                                mMonth = c.get(Calendar.MONTH);
                                mDay = c.get(Calendar.DAY_OF_MONTH);

                            // Launch Date Picker Dialog
                            DatePickerDialog dpd = new DatePickerDialog(obj,new DatePickerDialog.OnDateSetListener() {
                @Override
                                        public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
                                            // Display Selected date in textbox
                                        Dateval.setVisibility(View.VISIBLE);
                                            Dateval.setText(dayOfMonth + "-"+ (monthOfYear + 1) + "-" + year);
                }
                                    }, mYear, mMonth, mDay);
                                dpd.show();
                                date = mDay+"-"+mMonth+"-"+mYear;
                            }
                    });
               GregorianCalendar calendar = new GregorianCalendar(mYear,mMonth,mDay, mHour, mMinute);
               alarm_time = calendar.getTimeInMillis();
           }
        });


     alert.setTitle("ADD NOTE");
     alert.setView(alertLayout);
     alert.setCancelable(false);
     alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {

     @Override
     public void onClick(DialogInterface dialog, int which) {
     Toast.makeText(con, "Cancel clicked", Toast.LENGTH_SHORT).show();
     }
     });

     alert.setPositiveButton("ADD", new DialogInterface.OnClickListener() {

     @Override
     public void onClick(DialogInterface dialog, int which) {
     // code for matching password
     String note = Note.getText().toString();
     String lists = Lists.getText().toString() + '\n';

     int l=lists.length();
     int i=0;
     String one="";
     char q;
     String main1="";
     int count = 0,j=0;
     for (i=0;i<l;i++)
     {
         q=lists.charAt(i);
         if(q!='\n' )
             one += q;
         else
         { 
             Log.d("the string",":" + one);
             //Toast.makeText(getBaseContext(), "Words " + one , Toast.LENGTH_SHORT).show();
             main1 += count + " : " + one;
             lists1[j++] = one;
             one=""; 
         }
         count++;
     }
     Log.d("DISplay","111before finish add");
     if((date == null)^(time == null))
     {
         Toast.makeText(con, "Enter both date and time to set alarm", Toast.LENGTH_SHORT).show();
     }
     else{
     TaskDBHelper ob = new TaskDBHelper(obj1);
     SQLiteDatabase sqlDB = ob.getWritableDatabase();
     if((date != null)&(time != null))
     {
         String f1 = String.format("INSERT INTO prioritised (task,date,time,ringtone,done,Hidden) VALUES('"+note+"','"+date+"','"+time+"','"+""+"',0,"+MainActivity.getStat()+")");
         sqlDB.execSQL(f1);
         if((j!=0)&(main1!="\n") )
         {
             int id=0;
             Cursor cursor = sqlDB.rawQuery("SELECT _id from prioritised where task = '"+note+"'",null);

             if (cursor != null) {
                    try {
                        if (cursor.moveToFirst()) {
                            id = cursor.getInt(0);
                        }
                    } finally {
                        cursor.close();
                    }
                }
             Log.d("Prio"," "+id);
             String add;
             for(int k=0;k<j;k++)
             {
                 add = String.format("INSERT INTO sublistprioritised (_id1,sublist,done,hidden) VALUES("+id+",'"+lists1[k]+"',0,"+MainActivity.getStat()+")");
                 sqlDB.execSQL(add);
             }

         }

            /** Creating a Pending Intent */
            Context x=getBaseContext();
                            int requestID = (int) System.currentTimeMillis();
            PendingIntent operation = PendingIntent.getActivity(x, requestID, in,Intent.FLAG_ACTIVITY_NEW_TASK);

            /** Getting a reference to the System Service ALARM_SERVICE */
            AlarmManager alarmManager = (AlarmManager) x.getSystemService(ALARM_SERVICE);

            /** Setting an alarm, which invokes the operation at alart_time */
                    alarmManager.set(AlarmManager.RTC_WAKEUP  , alarm_time , operation);
                    /** Alert is set successfully */
                    Toast.makeText(x, "Alarm is set successfully",Toast.LENGTH_SHORT).show();
     }
     else{
     String f2 = String.format("INSERT INTO unprioritised (task,done,Hidden) VALUES('"+note+"',0,"+MainActivity.getStat()+")");
     sqlDB.execSQL(f2);
     if((j!=0)&(main1!="\n") )
     {
         int id=0;
         Cursor cursor = sqlDB.rawQuery("SELECT _id from unprioritised where task = '"+note+"'",null);
         if (cursor != null) {
                try {
                    if (cursor.moveToFirst()) {
                        id = cursor.getInt(0);
                    }
                } finally {
                    cursor.close();
                }
            }
         String add;
         for(int k=0;k<j;k++)
         {
             add = String.format("INSERT INTO sublistunprioritised (_id1,sublist,done,Hidden) VALUES("+id+",'"+lists1[k]+"',0,"+MainActivity.getStat()+")");
             sqlDB.execSQL(add);
         }

     }
     }
     }
     }
     });
     AlertDialog dialog = alert.create();
     dialog.show();
     }
}

谢谢。感谢您的帮助。

这是 Logcat

04-02 13:38:03.922: E/AndroidRuntime(2120): FATAL EXCEPTION: main
04-02 13:38:03.922: E/AndroidRuntime(2120): Process: com.example.todotry_1, PID: 2120
04-02 13:38:03.922: E/AndroidRuntime(2120): java.lang.NullPointerException
04-02 13:38:03.922: E/AndroidRuntime(2120): at android.app.PendingIntent.getActivity(PendingIntent.java:257)
04-02 13:38:03.922: E/AndroidRuntime(2120): at android.app.PendingIntent.getActivity(PendingIntent.java:224)
04-02 13:38:03.922: E/AndroidRuntime(2120): at com.example.todotry_1.DisplayAlertMessage$4.onClick(DisplayAlertMessage.java:244)
04-02 13:38:03.922: E/AndroidRuntime(2120): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
04-02 13:38:03.922: E/AndroidRuntime(2120): at android.os.Handler.dispatchMessage(Handler.java:102)
04-02 13:38:03.922: E/AndroidRuntime(2120): at android.os.Looper.loop(Looper.java:136)
04-02 13:38:03.922: E/AndroidRuntime(2120): at android.app.ActivityThread.main(ActivityThread.java:5017)
04-02 13:38:03.922: E/AndroidRuntime(2120): at java.lang.reflect.Method.invokeNative(Native Method)
04-02 13:38:03.922: E/AndroidRuntime(2120): at java.lang.reflect.Method.invoke(Method.java:515)
04-02 13:38:03.922: E/AndroidRuntime(2120): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-02 13:38:03.922: E/AndroidRuntime(2120): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-02 13:38:03.922: E/AndroidRuntime(2120): at dalvik.system.NativeStart.main(Native Method)

更新日志:

04-02 15:59:03.140: E/AndroidRuntime(1880): android.database.sqlite.SQLiteConstraintException: columns _id1, sublist are not unique (code 19)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.database.sqlite.SQLiteConnection.nativeExecuteForChangedRowCount(Native Method)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.database.sqlite.SQLiteConnection.executeForChangedRowCount(SQLiteConnection.java:734)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.database.sqlite.SQLiteSession.executeForChangedRowCount(SQLiteSession.java:754)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.database.sqlite.SQLiteStatement.executeUpdateDelete(SQLiteStatement.java:64)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1674)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1603)
04-02 15:59:03.140: E/AndroidRuntime(1880): at com.example.todotry_1.DisplayAlertMessage$4.onClick(DisplayAlertMessage.java:236)
04-02 15:59:03.140: E/AndroidRuntime(1880): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.os.Handler.dispatchMessage(Handler.java:102)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.os.Looper.loop(Looper.java:136)
04-02 15:59:03.140: E/AndroidRuntime(1880): at android.app.ActivityThread.main(ActivityThread.java:5017)
04-02 15:59:03.140: E/AndroidRuntime(1880): at java.lang.reflect.Method.invokeNative(Native Method)
04-02 15:59:03.140: E/AndroidRuntime(1880): at java.lang.reflect.Method.invoke(Method.java:515)
04-02 15:59:03.140: E/AndroidRuntime(1880): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-02 15:59:03.140: E/AndroidRuntime(1880): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-02 15:59:03.140: E/AndroidRuntime(1880): at dalvik.system.NativeStart.main(Native Method)

Answer 1

看起来这里没有必要调用getBaseContext()，而且你可能不想使用currentTimeMillis()作为requestCode，以防万一曾经需要取消PendingIntent:

/** Creating a Pending Intent */
            //Context x=getBaseContext();
            //int requestID = (int) System.currentTimeMillis();

            PendingIntent operation = null;
            //Make sure nothing is null for debugging purposes
            if (con == null){
                Log.e("onCLICK","con is null");
            }
            else if (in == null){
                Log.e("onCLICK","in is null");
            }
            else{
                operation = PendingIntent.getActivity(con, 0, in,PendingIntent.FLAG_UPDATE_CURRENT);
            }

            if (operation != null){
               /** Getting a reference to the System Service ALARM_SERVICE */
               AlarmManager alarmManager = (AlarmManager) con.getSystemService(ALARM_SERVICE);

               /** Setting an alarm, which invokes the operation at alart_time */
                alarmManager.set(AlarmManager.RTC_WAKEUP  , alarm_time , operation);
                /** Alert is set successfully */
                Toast.makeText(con, "Alarm is set successfully",Toast.LENGTH_SHORT).show();

            }

也请查看此帖子以获取示例:PendingIntent works correctly for the first notification but incorrectly for the rest

编辑:我刚刚将 PendingIntent 代码放入 AndroidStudio，它给了我这条消息:

Must be one or more of: PendingIntent.FLAG_ONE_SHOT, PendingIntent.FLAG_NO_CREATE, PendingIntent.FLAG_CANCEL_CURRENT, PendingIntent.FLAG_UPDATE_CURRENT, Intent.FILL_IN_ACTION, Intent.FILL_IN_DATA, Intent.FILL_IN_CATEGORIES, Intent.FILL_IN_COMPONENT, Intent.FILL_IN_PACKAGE, Intent.FILL_IN_SOURCE_BOUNDS, Intent.FILL_IN_SELECTOR, Intent.FILL_IN_CLIP_DATA less... (Ctrl+F1) Reports two types of problems: Supplying the wrong type of resource identifier. For example, when calling Resources.getString(int id), you should be passing R.string.something, not R.drawable.something. Passing the wrong constant to a method which expects one of a specific set of constants. For example, when calling View#setLayoutDirection, the parameter must be android.view.View.LAYOUT_DIRECTION_LTR or android.view.View.LAYOUT_DIRECTION_RTL.

看看The Documentation有关要在此处使用的有效标志的更多信息。