android学习笔记(3)Button控件的学习

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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

<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@Overridepublic 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>

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@Overridepublic 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>

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