Android初学：联系创建Activity

public class Activity2 extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
//
setContentView(R.layout.layout2);
System.out.println("这是我运行的第一个Activity");
Log.d("text","Log输出的信息");
}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">//匹配父窗口

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="大家好"
/>//内容包裹

</LinearLayout>