Notification的使用，有点复杂，哈哈哈，需要的时候来看看
.setContentTitle(“官方通知”)
.setContentText(“世界那么大，想去走走吗？”)
.setSmallIcon(R.drawable.ic_baseline_tonality_24)
.setLargeIcon(BitmapFactory.decodeResource(getResources(),R.drawable.logo))
.setColor(Color.parseColor("#FF0000"))
.setContentIntent(pendingIntent)
.setAutoCancel(true)
.build();

package com.example.tonghzi_notification;

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Build;
import android.os.Bundle;
import android.view.View;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;

public class MainActivity extends AppCompatActivity {
private NotificationManager manager;
private Notification notification;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
           NotificationChannel channel =  new NotificationChannel("leo","测试通知",
                    NotificationManager.IMPORTANCE_HIGH);
            manager.createNotificationChannel(channel);
        }
        Intent intent = new Intent(this,MainActivity2.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(this,0,intent,0);
         notification = new NotificationCompat.Builder(this,"leo")
                .setContentTitle("官方通知")
                .setContentText("世界那么大，想去走走吗？")
                .setSmallIcon(R.drawable.ic_baseline_tonality_24)
                .setLargeIcon(BitmapFactory.decodeResource(getResources(),R.drawable.logo))
                 .setColor(Color.parseColor("#FF0000"))
                 .setContentIntent(pendingIntent)
                 .setAutoCancel(true)
                .build();
    }
    public void sendNotifcation(View view) {
            manager.notify(1,notification);
//         Intent intent = new Intent(this,MainActivity2.class);
//         setIntent(intent);
    }
    public void cacelNotifcation(View view) {
        manager.cancel(1);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="sendNotifcation"
    android:text="发出通知"
    />
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="cacelNotifcation"
        android:text="取消通知"
        />
</LinearLayout>