android学习笔记(3)Button控件的学习

r囧r小猫 2022-08-03 12:58 224阅读 0赞

一,加入一个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

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

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,

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) {
 		//注意View是什么,然后下面为什么要强制转换成button!!
 		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;
 		}
 	
 		
 	}
 };