如何在Android應用中顯示通知計數？

此示例演示如何在Android應用啟動器中顯示通知計數。

步驟 1 - 在Android Studio中建立一個新專案，轉到檔案 ⇒ 新建專案，並填寫所有必需的詳細資訊以建立新專案。

步驟 2 - 將以下程式碼新增到res/layout/activity_main.xml。

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://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>

步驟 3 - 將以下程式碼新增到src/MainActivity.java

package com.app.sample;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.app.NotificationChannel ;
import android.app.NotificationManager ;
import android.app.PendingIntent ;
import android.content.Intent ;
import android.os.Bundle ;
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);
   }
   @SuppressLint("WrongConstant")
      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 Listener Service 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()) ;
   }
}

步驟 4 - 將以下程式碼新增到Manifests/AndroidManifest.xml

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

讓我們嘗試執行您的應用程式。我假設您已將您的實際Android移動裝置連線到您的計算機。要從Android Studio執行該應用程式，請開啟您的一個專案活動檔案，然後單擊執行工具欄中的圖示。選擇您的移動裝置作為選項，然後檢查您的移動裝置，它將顯示您的預設螢幕 -