android学习笔记(3)Button控件的学习

//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");
}
}

<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,这个要弄明白!!!!,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>

<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,然后下面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>