How To Multiple Permissions In Android Studio

1) AndroidMenifest.xml

<?xml version="1.0" encoding="utf-8"?>

 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 

 package="com.example.multiplepermissiontest">     

 <uses-permission android:name="android.permission.CAMERA"/> 

 <uses-permission android:name="android.permission.READ_CONTACTS"/> 

 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/> 

 <application 

      android:allowBackup="true"  

      android:icon="@mipmap/ic_launcher" 

      android:label="@string/app_name" 

      android:roundIcon="@mipmap/ic_launcher_round" 

      android:supportsRtl="true" 

      android:theme="@style/AppTheme"> 

 <activity android:name=".MainActivity"> 

 <intent-filter> 

 <action android:name="android.intent.action.MAIN" /> 

 <category android:name="android.intent.category.LAUNCHER" /> 

 </intent-filter> 

 </activity> 

 </application>
</manifest>

2). activity_main.xml

Layout xml file 

<?xml version="1.0" encoding="utf-8"?>

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 

 xmlns:tools="http://schemas.android.com/tools"

     android:layout_width="match_parent"

     android:layout_height="match_parent"

     android:gravity="center"

     android:orientation="horizontal" 

     android:padding="10dp"

     tools:context=".MainActivity">
    <Button 

         android:id="@+id/btn_request" 

         android:layout_width="wrap_content"

         android:layout_height="wrap_content"

         android:text="Request Permission"

         android:layout_weight="1"/> 

    <Button         

         android:id="@+id/btn_check"

         android:layout_width="wrap_content"

         android:layout_height="wrap_content" 

         android:text="Check Permission" 

         android:layout_weight="1"/> 

</LinearLayout>

3). MainActivity.java

In this class we have implement CHECK and REQUEST an CAMERA, READ_CONTACT and READ_EXTERNAL_STORAGE

package com.example.multiplepermissiontest;
import android.app.AlertDialog; 

import android.content.DialogInterface;

import android.content.Intent; 

import android.net.Uri; 

import android.os.Bundle;

import android.provider.Settings;

import android.view.View;

import android.widget.Button; 

import android.widget.Toast;
import androidx.annotation.NonNull; 

import androidx.appcompat.app.AppCompatActivity;

import androidx.core.app.ActivityCompat;

import androidx.core.content.ContextCompat;
public class MainActivity extends AppCompatActivity {

    static final int REQUEST_CODE = 123;  

// value must you choose any value 123, 100, 111 etc 

 Button btn_request; 

 Button btn_check;
    @Override 

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); 

       setContentView(R.layout.activity_main);
        btn_request = findViewById(R.id.btn_request); 

        btn_check = findViewById(R.id.btn_check);
        btn_request.setOnClickListener(new View.OnClickListener() {
       @Override 

       public void onClick(View v) {
                if (ContextCompat.checkSelfPermission(MainActivity.this, "android.permission.CAMERA") +
                        ContextCompat.checkSelfPermission(MainActivity.this, "android.permission.READ_CONTACTS") +
                        ContextCompat.checkSelfPermission(MainActivity.this, "android.permission.READ_EXTERNAL_STORAGE") == 0) {
                    Toast.makeText(MainActivity.this, "Permission already granted..", Toast.LENGTH_SHORT).show(); 

 } else if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, "android.permission.CAMERA") ||
                        ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, "android.permission.READ_CONTACTS") ||
                        ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, "android.permission.READ_EXTERNAL_STORAGE")) 

{
                     

 final AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this); 

 builder.setTitle("Grant those Permission"); 

 builder.setMessage("Camera, Read Contact and Read Storage"); 

 builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
 @Override 

 public void onClick(DialogInterface dialog, int which) {

 ActivityCompat.requestPermissions(MainActivity.this,

 new String[]{"android.permission.CAMERA", "android.permission.READ_CONTACTS",

 "android.permission.READ_EXTERNAL_STORAGE"}, MainActivity.REQUEST_CODE); 

 }
 }); 

 builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                        @Override 

                       public void onClick(DialogInterface dialog, int which) {
                            // no code 

                     }
                    });

                     builder.create().show(); 

  } else {
                    ActivityCompat.requestPermissions(MainActivity.this,

                    new String[]{"android.permission.CAMERA", "android.permission.READ_CONTACTS",

 "android.permission.READ_EXTERNAL_STORAGE"}, MainActivity.REQUEST_CODE);                }
            }
        });        btn_check.setOnClickListener(new View.OnClickListener() {
            @Override            public void onClick(View v) {

                Intent intent = new Intent();

                intent.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS); 

 intent.setData(Uri.fromParts("package", MainActivity.this.getPackageName(), null)); 

                startActivity(intent); 

 }
        }); 

     }

    @Override 

    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults); 

 if (requestCode != REQUEST_CODE) {
            return; 

 }
        // if permissions more then 3 then increment upto permissions 

        if (grantResults.length <= 0 || grantResults[0] + grantResults[1] + grantResults[2] != 0)

       {

       Toast.makeText(MainActivity.this, "Permissions Denied..", Toast.LENGTH_SHORT).show(); 

 } else {
            Toast.makeText(MainActivity.this, "Permissions Granted..", Toast.LENGTH_SHORT).show(); 

 }
    }
}