android学习笔记(3)Button控件的学习

一,增加一个button并用外部类绑定事件

//XML文件:    
<Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:text="扣子1" />
//主类:
public class MainActivity extends Activity {
     
	private Button btn1 = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn1 = (Button)findViewById(R.id.button1);         
	btn1.setOnClickListener(new buttonclick());   //方法一，定义外部类来绑定事件

 class buttonclick implements OnClickListener {
		public void onClick(View arg0) { 
			System.out.printline("点击了button1"); 		
			}	
    } 

二,用内部类绑定事件

<span style="color: rgb(51, 51, 51);">btn1.setOnClickListener(new OnClickListener() {  //方法二，定义</span><span style="color:#ff0000;"><strong>内部类</strong></span><span style="color: rgb(51, 51, 51);">来绑定事件
			
		@Override
		public void onClick(View arg0) {
		//用Toast来显示提示
		</span><span style="color:#ff0000;"><strong>//注意:Toast.makeText(Context context, CharSequence text, int duration)</strong></span><span style="color: rgb(51, 51, 51);">
		</span><span style="color:#ff0000;"><strong>//context要指向主类自己,这个要弄明确!!!!,text设置文本,duration设置时间</strong></span><span style="color:#333333;">
		Toast.makeText(getApplicationContext(), "click!", Toast.LENGTH_LONG).show();
				
		}
});</span>

三,有多个button,将内部类设置成变量使代码更友好
xml文件就不多说了,

<span style="color:#333333;">private Button btn1 = null;
	private Button btn2 = null;        
        btn1 = (Button)findViewById(R.id.button1);         
        btn2 = (Button)findViewById(R.id.button2);
        btn1.setOnClickListener(listener);     //有多个button
        btn2.setOnClickListener(listener); 


private OnClickListener listener =new OnClickListener() {  //定义一个变量来装这个内部类
	
	@Override
	public void onClick(View v) {
		</span><span style="color:#ff0000;"><strong>//注意View是什么,然后以下为什么要强制转换成button!!</strong></span><span style="color:#333333;">
		Button btn = (Button)v;
		switch (btn.getId()) {
		case R.id.button1:
			Toast.makeText(getApplicationContext(), "click1!", Toast.LENGTH_LONG).show();
			break;


		case R.id.button2:
			Toast.makeText(getApplicationContext(), "click2!", Toast.LENGTH_LONG).show();
			break;
		}
	
		
	}
};</span>