Read and Write permission for storage and gallery usage for marshmallow

Question

I am developing an android app in which it is required to provide permission for Read and write external storage. My requirement is to select a picture from gallery and use

Answer 1

Checking every situation

if denied - showing Alert dialog to user why we need permission

public static final int STORAGE_PERMISSION_REQUEST_CODE= 1;


    private void askPermissions() {

    int permissionCheckStorage = ContextCompat.checkSelfPermission(this,
            Manifest.permission.WRITE_EXTERNAL_STORAGE); 

   // we already asked for permisson & Permission granted, call camera intent
    if (permissionCheckStorage == PackageManager.PERMISSION_GRANTED) {

        //do what you want

    } else {

           // if storage request is denied
        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setMessage("You need to give permission to access storage in order to work this feature.");
            builder.setNegativeButton("CANCEL", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    dialogInterface.dismiss();
                }
            });
            builder.setPositiveButton("GIVE PERMISSION", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    dialogInterface.dismiss();

                    // Show permission request popup
                    ActivityCompat.requestPermissions(this,
                            new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                            STORAGE_PERMISSION_REQUEST_CODE);
                }
            });
            builder.show();

        } //asking permission for first time 
          else {
             // Show permission request popup for the first time
                        ActivityCompat.requestPermissions(AddWorkImageActivity.this,
                                new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                                STORAGE_PERMISSION_REQUEST_CODE);

                    }

    }
}

Checking Permission Results

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

    switch (requestCode) {
        case STORAGE_PERMISSION_REQUEST_CODE:
            if (grantResults.length > 0 && permissions[0].equals(Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
                // check whether storage permission granted or not.
                if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    //do what you want;
                }
            }
            break;
        default:
            break;
    }
}

you can just copy and paste this code, it works fine. change context(this) & permissions according to you.