بستن پنجره ها با Back

package noorhoseini.mahdi.apps;

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


public class SecondActivity extends Activity {

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.myform2);

        Button btnback = (Button) findViewById(R.id.btnback);

        Button btnexit = (Button) findViewById(R.id.btnexit);

        btnback.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent intent = new Intent(SecondActivity.this, FirstActivity.class);
                SecondActivity.this.startActivity(intent);
            }
        });

        btnexit.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                SecondActivity.this.finish();
            }
        });
    }
}