Button Action in Android Studio

Source Code Java:

package ap.android;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;

public class LinkButtons extends Activity {

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

    public void goToSo (View view) {
        goToUrl ( "http://stackoverflow.com/");
    }

    public void goToSu (View view) {
        goToUrl ( "http://superuser.com/");
    }

    private void goToUrl (String url) {
        Uri uriUrl = Uri.parse(url);
        Intent launchBrowser = new Intent(Intent.ACTION_VIEW, uriUrl);
        startActivity(launchBrowser);
    }

}

Source Code Android XML:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent">
    <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/select" />
    <Button android:layout_height="wrap_content" android:clickable="true" android:autoLink="web" android:cursorVisible="true" android:layout_width="match_parent" android:id="@+id/button_so" android:text="StackOverflow" android:linksClickable="true" android:onClick="goToSo"></Button>
    <Button android:layout_height="wrap_content" android:layout_width="match_parent" android:text="SuperUser" android:autoLink="web" android:clickable="true" android:id="@+id/button_su" android:onClick="goToSu"></Button>
</LinearLayout>