有兩種方法：

1. 需要許可權  <uses-permission android:name="android.permission.GET_TASKS"/>， 普通App也可獲取，不需要確認，Android 5.1 之後已經廢棄，但是 compileSdkVersion 設為 28 還可以使用，方法如下：

public static boolean isApplicationBroughtToBackground(final Context context) {
        ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(1);
        if (!tasks.isEmpty()) {
            ComponentName topActivity = tasks.get(0).topActivity;
            if (!topActivity.getPackageName().equals(context.getPackageName())) {
                return true;
            }
        }
        return false;
    }
 

2. 不需要許可權：

public static boolean isBackground(Context context) {
        ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
            if (appProcess.processName.equals(context.getPackageName())) {
                if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_BACKGROUND) {
                    Log.i("後臺", appProcess.processName);
                    return true;
                }else{
                    Log.i("前臺", appProcess.processName);
                    return false;
                }
            }
        }
        return false;
    }
 

其他，獲取當前 App 程序名字：

public static String getCurrentProcessName(Context context) {
        try {
            int myid = Process.myPid();
            ActivityManager am = (ActivityManager)context.getSystemService(Context.ACTIVITY_SERVICE);
            List<ActivityManager.RunningAppProcessInfo> appProcesses = am.getRunningAppProcesses();
            Iterator iter = appProcesses.iterator();

            while(iter.hasNext()) {
                ActivityManager.RunningAppProcessInfo info = (ActivityManager.RunningAppProcessInfo)iter.next();
                if (info.pid == myid) {
                    return info.processName;
                }
            }
        } catch (Exception e) {
            
        }

        return null;
    }