gistfile1.txt

package learning.com.defaultscreens;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {

    Button button;

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

    public void addListenerOnButton() {

        final Context context = this;

        button = (Button) findViewById(R.id.button1);

        button.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {

                Toast.makeText(MainActivity.this,"Hello! World",Toast.LENGTH_LONG).show();
            }

        });

    }

}