Android4每日一例--第一天

HelloWorld
Helloworld,java
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;


public class HelloWorld extends Activity 
{
//当第一次创建该Activity时回调该方法
@Override
public void onCreate(Bundle savedInstanceState) 
{
super.onCreate(savedInstanceState);
//设置使用main.xml文件定义的页面布局
setContentView(R.layout.main);
//获取UI界面中ID为R.id.ok的按钮
Button bn = (Button)findViewById(R.id.ok);
//为按钮绑定一个单击事件的易做图
bn.setOnClickListener(new OnClickListener(){
public void  onClick(View v)   
{
//获取UI界面中ID为R.id.show的文本框
final TextView show = (TextView)findViewById(R.id.show);
//改变文本框的文本内容
show.setText("Hello Android~" + new java.util.Date());
}
});        
}
}
点击按钮后文本框显示Hello Android加当前时间。
自动生成的R文件，
public final class R {
    public static final class attr {
    }
    public static final class drawable {
        public static final int icon=0x7f020000;
    }
    public static final class id {
        public static final int ok=0x7f050001;
        public static final int show=0x7f050000;
    }
    public static final class layout {
        public static final int main=0x7f030000;
    }
    public static final class string {
        public static final int app_name=0x7f040000;
    }
}

补充：移动开发 , Android ,