วิธีแสดงจำนวน Notification บนไอคอนแอป (Badge) ใน Android

ภาพรวม

บทความนี้สาธิตการแสดงตัวเลขจำนวน Notification (Badge Count) บนไอคอนแอปใน Launcher โดยใช้ setNumber() และ setBadgeIconType()

ขั้นตอนที่ 1: สร้างโปรเจกต์ใหม่

Android Studio → File → New Project → Empty Activity

ขั้นตอนที่ 2: Layout (res/layout/activity_main.xml)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:tools="https://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context=".MainActivity">
    <Button
        android:onClick="createNotification"
        android:text="create notification"
        android:layout_centerInParent="true"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</RelativeLayout>

ขั้นตอนที่ 3: MainActivity (src/MainActivity.java)

package app.tutorialspoint.com.notifyme;

import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.NotificationCompat;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import static android.app.Notification.BADGE_ICON_SMALL;

public class MainActivity extends AppCompatActivity {
    static int count = 0;
    public static final String NOTIFICATION_CHANNEL_ID = "10001";
    private final static String default_notification_channel_id = "default";

    @Override
    protected void onResume() {
        super.onResume();
        count = 0;
    }

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

    public void createNotification(View view) {
        count++;
        
        Intent notificationIntent = new Intent(getApplicationContext(), MainActivity.class);
        notificationIntent.putExtra("fromNotification", true);
        notificationIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);

        NotificationManager mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(getApplicationContext(), default_notification_channel_id);
        
        mBuilder.setContentTitle("My Notification");
        mBuilder.setContentIntent(pendingIntent);
        mBuilder.setContentText("Notification Badge Example");
        mBuilder.setSmallIcon(R.drawable.ic_launcher_foreground);
        mBuilder.setAutoCancel(true);
        mBuilder.setBadgeIconType(BADGE_ICON_SMALL);
        mBuilder.setNumber(count);

        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
            int importance = NotificationManager.IMPORTANCE_HIGH;
            NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, "NOTIFICATION_CHANNEL_NAME", importance);
            mBuilder.setChannelId(NOTIFICATION_CHANNEL_ID);
            assert mNotificationManager != null;
            mNotificationManager.createNotificationChannel(notificationChannel);
        }
        
        assert mNotificationManager != null;
        mNotificationManager.notify((int) System.currentTimeMillis(), mBuilder.build());
    }
}

ขั้นตอนที่ 4: AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android"
    package="app.tutorialspoint.com.notifyme">
    <uses-permission android:name="android.permission.VIBRATE" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
    <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>
    </application>
</manifest>

การทดสอบ

รันแอป กด Create Notification หลายครั้ง จะเห็นตัวเลขบนไอคอนแอปเพิ่มขึ้นตามจำนวน Notification