android - Request multiple permissions example

activity_main.xml

<?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:id="@+id/root_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    android:orientation="vertical"
    android:background="#e5ead3"
    >
    <Button
        android:id="@+id/btn_do_task"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Check Permissions"
        />
</LinearLayout>

MainActivity.java

package com.cfsuman.me.androidcodesnippets;

import android.Manifest;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.os.Build;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {
    private Context mContext;
    private Activity mActivity;

    private LinearLayout mRootLayout;
    private Button mBtnDoTask;

    private static final int MY_PERMISSIONS_REQUEST_CODE = 123;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Get the application context
        mContext = getApplicationContext();
        mActivity = MainActivity.this;

        // Get the widget reference from xml layout
        mRootLayout = findViewById(R.id.root_layout);
        mBtnDoTask = findViewById(R.id.btn_do_task);

        // Set a click listener for the button
        mBtnDoTask.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
                    checkPermission();
                }
            }
        });
    }

    protected void checkPermission(){
        if(ContextCompat.checkSelfPermission(mActivity,Manifest.permission.CAMERA)
                    + ContextCompat.checkSelfPermission(
                            mActivity,Manifest.permission.READ_CONTACTS)
                    + ContextCompat.checkSelfPermission(
                            mActivity,Manifest.permission.WRITE_EXTERNAL_STORAGE)
                    != PackageManager.PERMISSION_GRANTED){

            // Do something, when permissions not granted
            if(ActivityCompat.shouldShowRequestPermissionRationale(
                    mActivity,Manifest.permission.CAMERA)
                    || ActivityCompat.shouldShowRequestPermissionRationale(
                            mActivity,Manifest.permission.READ_CONTACTS)
                    || ActivityCompat.shouldShowRequestPermissionRationale(
                            mActivity,Manifest.permission.WRITE_EXTERNAL_STORAGE)){
                // If we should give explanation of requested permissions

                // Show an alert dialog here with request explanation
                AlertDialog.Builder builder = new AlertDialog.Builder(mActivity);
                builder.setMessage("Camera, Read Contacts and Write External" +
                        " Storage permissions are required to do the task.");
                builder.setTitle("Please grant those permissions");
                builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        ActivityCompat.requestPermissions(
                                mActivity,
                                new String[]{
                                        Manifest.permission.CAMERA,
                                        Manifest.permission.READ_CONTACTS,
                                        Manifest.permission.WRITE_EXTERNAL_STORAGE
                                },
                                MY_PERMISSIONS_REQUEST_CODE
                        );
                    }
                });
                builder.setNeutralButton("Cancel",null);
                AlertDialog dialog = builder.create();
                dialog.show();
            }else{
                // Directly request for required permissions, without explanation
                ActivityCompat.requestPermissions(
                        mActivity,
                        new String[]{
                                Manifest.permission.CAMERA,
                                Manifest.permission.READ_CONTACTS,
                                Manifest.permission.WRITE_EXTERNAL_STORAGE
                        },
                        MY_PERMISSIONS_REQUEST_CODE
                );
            }
        }else {
            // Do something, when permissions are already granted
            Toast.makeText(mContext,"Permissions already granted",Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults){
        switch (requestCode){
            case MY_PERMISSIONS_REQUEST_CODE:{
                // When request is cancelled, the results array are empty
                if(
                        (grantResults.length >0) &&
                                (grantResults[0]
                                        + grantResults[1]
                                        + grantResults[2]
                                        == PackageManager.PERMISSION_GRANTED
                                )
                        ){
                    // Permissions are granted
                    Toast.makeText(mContext,"Permissions granted.",Toast.LENGTH_SHORT).show();
                }else {
                    // Permissions are denied
                    Toast.makeText(mContext,"Permissions denied.",Toast.LENGTH_SHORT).show();
                }
                return;
            }
        }
    }
}

AndroidManifest.xml [Permissions]

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