MainActivity.java

package nl.esdertf.deltionexternallibrary;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;

import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        LinearLayout layout = (LinearLayout) findViewById(R.id.layout);
        for(int i = 0; i < 3; i++){
            ImageView image = new ImageView(this);
            ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this).build();
            ImageLoader loader = ImageLoader.getInstance();
            loader.init(config);

            loader.displayImage("http://lorempixel.com/400/400/", image);

            layout.addView(image);
        }
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        LinearLayout layout = (LinearLayout) findViewById(R.id.layout);
        layout.removeAllViews();


        if (id == R.id.action_business) {
            for(int i = 0; i < 3; i++){
                ImageView image = new ImageView(this);
                ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this).build();
                ImageLoader loader = ImageLoader.getInstance();
                loader.init(config);

                loader.displayImage("http://lorempixel.com/400/400/business", image);

                layout.addView(image);
            }
            return true;
        }else if(id == R.id.action_people){
            for(int i = 0; i < 3; i++){
                ImageView image = new ImageView(this);
                ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this).build();
                ImageLoader loader = ImageLoader.getInstance();
                loader.init(config);

                loader.displayImage("http://lorempixel.com/400/400/people", image);

                layout.addView(image);
            }
            return true;
        }else if(id == R.id.action_sports){
            for(int i = 0; i < 3; i++){
                ImageView image = new ImageView(this);
                ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this).build();
                ImageLoader loader = ImageLoader.getInstance();
                loader.init(config);

                loader.displayImage("http://lorempixel.com/400/400/sports", image);

                layout.addView(image);
            }
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}