android-studio - 通知不会显示 android studio

Question

我试图在按下按钮时收到通知，但它没有显示出来。我遵循了很多教程，我认为它与 android 的版本有关。有渠道的东西。我只是不知道如何实现它。

package com.example.root.savetheworldv2;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    Button btn;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn = (Button) findViewById(R.id.button);
        btn.setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent intent =new Intent();
                        PendingIntent pIntent = 
PendingIntent.getActivity(MainActivity.this,0,intent,0);
                        Notification noti = new 
Notification.Builder(MainActivity.this)
                                .setTicker("TickerTitle")
                                .setContentTitle("Content Title")
                                .setContentText("Content Text")

.setSmallIcon(R.drawable.ic_launcher_background)

.setContentIntent(pIntent).getNotification();

                        noti.flags = Notification.FLAG_AUTO_CANCEL;
                        NotificationManager nm = 
(NotificationManager) getSystemService(NOTIFICATION_SERVICE);
                        nm.notify(0,noti);

标签： android-studioandroid-8.0-oreoandroid-9.0-pieandroid-8.1-oreo