警报管理器未运行

Question

I am attempting to create a more complex app but was unable to correctly use AlarmManager to open an activity. I tried distilling the code down just to the essence of what I'm missing is, but it still is not working correctly.

The app basically just accepts a minute and hour input along with a start button, and is supposed to open the second activity when the time is inputted. However, the second activity never opens at the time I enter, and nothing in LogCat seems to change. Here is my current code:

MANIFEST:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.goali.adalarm">

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <receiver android:name=".AlarmReceiver2" >

        <intent-filter>
            <action android:name="android.intent.alarmclock.ALARM_ALERT" />

            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </receiver>
    <activity android:name=".AlarmReceiver">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>
</application>
</manifest>

MainActivity:

   public class MainActivity extends AppCompatActivity {
    Calendar c;
    PendingIntent pendingIntent;
    AlarmManager alarmManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        c = Calendar.getInstance();
        alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
        final EditText hour = (EditText) findViewById(R.id.hour);
        final EditText minute = (EditText) findViewById(R.id.minute);
        Button button = (Button) findViewById(R.id.press);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                c.set(Calendar.HOUR_OF_DAY, (Integer.parseInt(hour.getText().toString())));
                c.set(Calendar.MINUTE, Integer.parseInt(minute.getText().toString()));
                c.set(Calendar.SECOND,0);
                c.set(Calendar.MILLISECOND,0);
                Intent intent = new Intent(MainActivity.this, AlarmReceiver.class);
                pendingIntent = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0);
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                    alarmManager.setExact(AlarmManager.RTC_WAKEUP,  c.getTimeInMillis(), pendingIntent);
                }
                Toast.makeText(MainActivity.this, "Alarm Set.", LENGTH_LONG).show();
            }
        });
    }
}

2nd activity:

public class AlarmReceiver extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_alarm_receiver);
    }
}

BroadcastReceiver:

public class AlarmReceiver2 extends BroadcastReceiver {


        @Override
        public void onReceive(Context context, Intent intent) {
            Intent intent2 = new Intent(context, AlarmReceiver.class);
            Toast.makeText(context, "Alarm worked.", Toast.LENGTH_LONG).show();
            context.startActivity(intent2);
        }
    }

Answer 1

From you code I guess you want to start an Activity or a Broadcast after amounts of time from now by using AlarmManager .

To start an activity ( AlarmReceiver ).

public class MainActivity extends AppCompatActivity {

    PendingIntent pendingIntent;
    AlarmManager alarmManager;

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

        alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
        final EditText hour = (EditText) findViewById(R.id.hour);
        final EditText minute = (EditText) findViewById(R.id.minute);
        Button button = (Button) findViewById(R.id.press);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int hours = Integer.parseInt(hour.getText().toString());
                int minutes = Integer.parseInt(minute.getText().toString());

                Intent intent = new Intent(MainActivity.this, AlarmReceiver.class);
                pendingIntent = PendingIntent.getActivity(MainActivity.this, 0, intent, 0);

                // 1 hour = 60 minutes = 3600 seconds = 3600000 milliseconds.
                long timeFromNowInMilliseconds = (hours * 3600000) + (minutes * 60000);

                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                    alarmManager.setExact(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + timeFromNowInMilliseconds, pendingIntent);
                }
                Toast.makeText(MainActivity.this, "Alarm Set.", LENGTH_LONG).show();
            }
        });
    }
}

To start a broadcast ( AlarmReceiver2 )

public class MainActivity extends AppCompatActivity {

    PendingIntent pendingIntent;
    AlarmManager alarmManager;

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

        alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
        final EditText hour = (EditText) findViewById(R.id.hour);
        final EditText minute = (EditText) findViewById(R.id.minute);
        Button button = (Button) findViewById(R.id.press);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int hours = Integer.parseInt(hour.getText().toString());
                int minutes = Integer.parseInt(minute.getText().toString());

                Intent intent = new Intent(MainActivity.this, AlarmReceiver2.class);
                pendingIntent = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0);

                // 1 hour = 60 minutes = 3600 seconds = 3600000 milliseconds.
                long timeFromNowInMilliseconds = (hours * 3600000) + (minutes * 60000);

                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                    alarmManager.setExact(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + timeFromNowInMilliseconds, pendingIntent);
                }
                Toast.makeText(MainActivity.this, "Alarm Set.", LENGTH_LONG).show();
            }
        });
    }
}