Runtime Permissions In Android >= 6

RuntimePermissionsActivity.java

package asaadi.hossin.app;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.SparseIntArray;

public abstract class RuntimePermissionsActivity extends AppCompatActivity {
    private SparseIntArray mErrorString;

    public abstract void onPermissionsGranted(int i);

    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.mErrorString = new SparseIntArray();
    }

    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        int permissionCheck = 0;
        for (int permission : grantResults) {
            permissionCheck += permission;
        }
        if (grantResults.length <= 0 || permissionCheck != 0) {
            finish();
        } else {
            onPermissionsGranted(requestCode);
        }
    }

    public void requestAppPermissions(String[] requestedPermissions, int stringId, int requestCode) {
        this.mErrorString.put(requestCode, stringId);
        int permissionCheck = 0;
        boolean shouldShowRequestPermissionRationale = false;
        for (String permission : requestedPermissions) {
            permissionCheck += ContextCompat.checkSelfPermission(this, permission);
            if (shouldShowRequestPermissionRationale || ActivityCompat.shouldShowRequestPermissionRationale(this, permission)) {
                shouldShowRequestPermissionRationale = true;
            } else {
                shouldShowRequestPermissionRationale = false;
            }
        }
        if (permissionCheck == 0) {
            onPermissionsGranted(requestCode);
        } else if (shouldShowRequestPermissionRationale) {
            ActivityCompat.requestPermissions(this, requestedPermissions, requestCode);
        } else {
            ActivityCompat.requestPermissions(this, requestedPermissions, requestCode);
        }
    }
}

SplashActivity.java

package asaadi.hossin.app;

import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.widget.TextView;

import asaadi.hossin.whatsappdownloader.Utils.RuntimePermissionsActivity;
import asaadi.hossin.whatsappdownloader.Utils.Utils;

public class SplashActivity extends RuntimePermissionsActivity {

    class MyRunnable implements Runnable {
        MyRunnable() {
        }

        public void run() {
            SplashActivity.this.requestAppPermissions(new String[]{"android.permission.WRITE_EXTERNAL_STORAGE"}, R.string.runtime_permissions_txt, 20);
        }
    }

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView((int) R.layout.activity_splash);
        TextView spashText = findViewById(R.id.spashText);

        Utils.setTypeFace(this,spashText);

        new Handler().postDelayed(new MyRunnable(), 500);
    }

    public void onPermissionsGranted(int requestCode) {
        if (requestCode == 20) {
            try {
                Intent i = new Intent(getApplicationContext(), MainActivity.class);
                startActivity(i);
                finish();
            } catch (Exception e) {
                e.printStackTrace();
                Log.d("eeeee", e.getLocalizedMessage());
            }
        }
    }
}