Set Notif Android Studio

package com.example.layanancomplain;

import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.VibrationEffect;
import android.os.Vibrator;
import android.preference.PreferenceManager;
import android.support.v4.app.NotificationCompat;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.CardView;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Toast;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class Menu_engineer extends AppCompatActivity {
    String ip="",PESAN="",id_penugasan;
    Handler mHandler;
    JSONParser jsonParser = new JSONParser();
    Vibrator vibrator;
    CardView btnProfil, btnPenugasan, btnArsip, btnExit;

    String id_user, nama_user;

    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.menu_engineer);
        ip=jsonParser.getIP();
        vibrator = (Vibrator) getSystemService(VIBRATOR_SERVICE);

        SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(Menu_engineer.this);
        Boolean Registered = sharedPref.getBoolean("Registered", false);
        if (!Registered){
            finish();
        }else {
            id_user= sharedPref.getString("id_user", "");
            nama_user = sharedPref.getString("nama_user", "");
        }

        btnProfil=(CardView)findViewById(R.id.btnProfil);
        btnProfil.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                Intent i = new Intent(Menu_engineer.this,Profil_user.class);
                i.putExtra("pk", id_user);
                startActivity(i);
            }});

        btnPenugasan=(CardView)findViewById(R.id.btnPenugasan);
        btnPenugasan.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                Intent i = new Intent(Menu_engineer.this,List_penugasan.class);
                startActivity(i);
            }});

        btnArsip=(CardView)findViewById(R.id.btnArsip);
        btnArsip.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                Intent i = new Intent(Menu_engineer.this,List_arsip_penugasan.class);
                startActivity(i);
            }});

        btnExit=(CardView)findViewById(R.id.btnExit);
        btnExit.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
               keluarYN();
            }});

        this.mHandler = new Handler();
        m_Runnable.run();
    }

    private final Runnable m_Runnable = new Runnable()    {
        public void run()  {
            new Menu_engineer.load().execute();
            Menu_engineer.this.mHandler.postDelayed(m_Runnable,5000);
        }
    };
    private void addNotification1() {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            vibrator.vibrate(VibrationEffect.createOneShot(1000, VibrationEffect.DEFAULT_AMPLITUDE));
        }

        Toast.makeText(Menu_engineer.this,"Info "+PESAN,Toast.LENGTH_SHORT).show();
        NotificationCompat.Builder builder =
                new NotificationCompat.Builder(this)
                        .setSmallIcon(R.drawable.phone_icon)
                        .setContentTitle("Konfirmasi Teknisi Untuk Penugasan ")
                        .setContentText(PESAN);

        Intent notificationIntent = new Intent(this, NorifCustomer.class);//eventList        notificationIntent.putExtra("id_penugasan", id_penugasan);
        notificationIntent.putExtra("PESAN", PESAN);

        PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent,PendingIntent.FLAG_UPDATE_CURRENT);
        builder.setContentIntent(contentIntent);
        NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        manager.notify(0, builder.build());

    }
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            keluarYN();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

    public void keluar(){
        new AlertDialog.Builder(this)
                .setTitle("Menutup Aplikasi")
                .setMessage("Terimakasih... Anda Telah Menggunakan Aplikasi Ini")
                .setNeutralButton("Tutup", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dlg, int sumthin) {
                        finish();
                    }})
                .show();
    }


    public void keluarYN(){
        AlertDialog.Builder ad=new AlertDialog.Builder(Menu_engineer.this);
        ad.setTitle("Konfirmasi");
        ad.setMessage("Apakah benar ingin keluar?");

        ad.setPositiveButton("OK",new DialogInterface.OnClickListener(){
            @Override            public void onClick(DialogInterface dialog, int which) {
                keluar();
            }});

        ad.setNegativeButton("No",new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface arg0, int arg1) {
            }});

        ad.show();
    }


    int adabaru=0;
    class load extends AsyncTask<String, String, String> {
        @Override        protected void onPreExecute() {
            super.onPreExecute();
        }
        protected String doInBackground(String... args) {
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("id_user", id_user));
            JSONObject json = jsonParser.makeHttpRequest(ip+"penugasanteknisi.php", "GET", params);
            Log.d("show: ", json.toString());
            try {
                adabaru= json.getInt("sukses");
                if(adabaru==1){
                    PESAN= json.getString("PESAN");
                    id_penugasan= json.getString("id_penugasan");
                }
            }
            catch (JSONException e) {e.printStackTrace();}
            return null;
        }

        protected void onPostExecute(String file_url) {
            runOnUiThread(new Runnable() {
                public void run() {
                    if (adabaru==1){
                        adabaru=0;
                        addNotification1();
                        Toast.makeText(Menu_engineer.this,"Ada Info dari Petugas...="+PESAN,Toast.LENGTH_SHORT).show();
                    }
                }
            });}
    }

}

<?php 
require_once"konmysqli.php";
$respon = array();

if (isset($_GET["id_user"])) {
    $id_user = $_GET['id_user'];
 $sql="SELECT * FROM `$tbpenugasan` WHERE `$tbpenugasan`.`id_user` = 
 '$id_user' and  `$tbpenugasan`.`notif_teknisi`='0'";
    
 $jum=getJum($conn,$sql);
    if ($jum>0) {
            $d=getField($conn,$sql);
      $record = array();
            $id_penugasan = $d["id_penugasan"];
   $pesanketeknisi= $d["pesan"];
   $id_user = $d["id_user"];
   $status = $d["status"];
   $id_complain= $d["id_complain"];
   
   $namateknisi=getUserM($conn,$id_user);
   $pesan= $d["pesan"];
   
   $respon["pesankecustomer"]="Status $status |Penugasan ke Teknisi $namateknisi ($id_user)";
   
   $respon["PESAN"]="$pesan (NO Complain $id_complain)";
   
   $respon["id_penugasan"]=$id_penugasan;
   $respon["pesan"] =$pesan;
   
   
            $respon["sukses"] = 1;
   
   $sqlm="update `$tbpenugasan` set `notif_teknisi`='1' WHERE `id_penugasan` = '$id_penugasan'";
   //processM($conn,$sqlm);
   
   
             $respon["pesan"] = "$jum record";
   echo json_encode($respon);
        } else {
            $respon["sukses"] = 0;
            $respon["pesan"] = "0 record";
            echo json_encode($respon);
        }

} else {
    $respon["sukses"] = 0;
    $respon["pesan"] = "? lengkapi data";
    echo json_encode($respon);
}
?>

<?php

function getJum($conn,$sql){
  $rs=$conn->query($sql);
  $jum= $rs->num_rows;
 $rs->free();
 return $jum;
}

function getField($conn,$sql){
 $rs=$conn->query($sql);
 $rs->data_seek(0);
 $d= $rs->fetch_assoc();
 $rs->free();
 return $d;
}
?>