Multiple Permissions Android-CodePudding

I want to build java class that managing all my permissions I start with ReadContacts from Phone Permissions.java

import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

public class Permissions {


    public void checkPermission(Context t, Activity s) {
        //check condition
  
        if(ContextCompat.checkSelfPermission(t, Manifest.permission.READ_CONTACTS)
                != PackageManager.PERMISSION_GRANTED){
            //when permission is not granted
            //Request permission
            ActivityCompat.requestPermissions(s,new String[]{Manifest.permission.READ_CONTACTS},100);

        }else{
            //when permission is granted
            //create method

        }
    }



}

and I pass from MainActivity the Context and activity

MainActivity.java

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    public Permissions permissions;
    Context appContext;
    Activity activity;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        appContext = getApplicationContext();


        permissions.checkPermission(appContext,MainActivity.this);
    }


    private void checkPermission() {
        //check condition

        if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_CONTACTS)
                != PackageManager.PERMISSION_GRANTED){
            //when permission is not granted
            //Request permission
            ActivityCompat.requestPermissions(MainActivity.this,new String[]{Manifest.permission.READ_CONTACTS},100);

        }else{
            //when permission is granted
            //create method
            Toast.makeText(this,"permission Access",Toast.LENGTH_SHORT);
        }
    }

}

and what it's does is crashing my app I know that my problem it when I pass the context and the activity , I try to only send the activity and its also crashing my app

Thanks for Assistance

CodePudding user response：

It seems that you have not instantiated the permissions of type Permissions in your MainActivity class. Thus you're calling the checkPermission() method on a null object reference.

Possible Fixes

public class MainActivity extends AppCompatActivity {
    public Permissions permissions;
    Context appContext;
    Activity activity;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        appContext = getApplicationContext();

        permissions = new Permissions();
        permissions.checkPermission(appContext,MainActivity.this);
    }
    
    // Rest of the code...
}

Alternatively...

You can alternatively declare the checkPermission method as static to be able to call it without instantiating.

public class Permissions {

    public static void checkPermission(Context t, Activity s) {
        //check condition
  
        if(ContextCompat.checkSelfPermission(t, Manifest.permission.READ_CONTACTS)
                != PackageManager.PERMISSION_GRANTED){
            //when permission is not granted
            //Request permission
            ActivityCompat.requestPermissions(s,new String[]{Manifest.permission.READ_CONTACTS},100);

        }else{
            //when permission is granted
            //create method

        }
    }
}

then you call it in the MainActivity like following

public class MainActivity extends AppCompatActivity {
    
    Context appContext;
    Activity activity;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        appContext = getApplicationContext();

        Permissions.checkPermission(appContext,MainActivity.this);
    }
    
    // Rest of the code...
}