然後發送通知：

代碼如下：

package shurui.loyal888.com.myapplication;

import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.os.Build;
import android.os.Bundle;
import android.os.PersistableBundle;
import android.support.v4.app.NotificationCompat;
import
 
 android.support.v4.app.NotificationManagerCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {
    private static final
 
 String TAG = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        createNotificationChannel();
        
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this
 
, "1")
                .setSmallIcon(R.mipmap.ic_launcher)
                .setContentTitle("My notification")
                .setContentText("Much longer text that cannot fit one line...")
                .setStyle(new NotificationCompat.BigTextStyle()
                        .bigText("Much longer text that cannot fit one line..."))
                .setPriority(NotificationCompat.PRIORITY_DEFAULT);
        NotificationManagerCompat notificationManager = NotificationManagerCompat.from(this);

// notificationId is a unique int for each notification that you must define
        notificationManager.notify(1, builder.build());

    }

    @Override
    public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {

        super.onSaveInstanceState(outState, outPersistentState);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.example_menu, menu);
        return true;
    }
    public void onGroupItemClick(MenuItem item) {}

    @Override
    protected void onRestart() {
        Log.i(TAG, "onRestart: ");
        super.onRestart();
    }

    /**
     * android 8.0 以上通知 必須先獲取chanle
     */
    private void createNotificationChannel() {
        // Create the NotificationChannel, but only on API 26+ because
        // the NotificationChannel class is new and not in the support library
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            CharSequence name = getString(R.string.appbar_scrolling_view_behavior);
            String description = getString(R.string.appbar_scrolling_view_behavior);
            int importance = NotificationManager.IMPORTANCE_HIGH;
            NotificationChannel channel = new NotificationChannel("1", name, importance);
            channel.setDescription(description);
            // Register the channel with the system; you can‘t change the importance
            // or other notification behaviors after this
            NotificationManager notificationManager = getSystemService(NotificationManager.class);
            notificationManager.createNotificationChannel(channel);
        }
    }

}

安卓8.0及以上使用通知