Main Activity Picasso

package com.yoesuv.demopicasso;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.ImageView;
import android.widget.ProgressBar;

import com.squareup.picasso.Callback;
import com.squareup.picasso.Picasso;

public class MainActivity extends AppCompatActivity {

    private ImageView imgView;
    private ProgressBar pBar;

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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        if(getSupportActionBar()!=null){
            getSupportActionBar().setElevation(5);
        }

        imgView = (ImageView) findViewById(R.id.imageView);
        pBar = (ProgressBar) findViewById(R.id.progress);

        imgView.setVisibility(View.GONE);
        pBar.setVisibility(View.VISIBLE);

        Picasso.with(this).load(getResources().getString(R.string.url_gambar)).into(imgView, new Callback() {
            @Override
            public void onSuccess() {
                pBar.setVisibility(View.GONE);
                imgView.setVisibility(View.VISIBLE);
            }

            @Override
            public void onError() {
                pBar.setVisibility(View.GONE);
                imgView.setVisibility(View.VISIBLE);
                imgView.setImageResource(R.drawable.no_image);
            }
        });

    }
}