Posted on 2006-07-09 23:49
Yemoo'S Java Blog 閱讀(1841)
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JAVA基礎知識
這算是一個很簡單的程序,但還是值得我這樣的初學者去總結一下,畢竟applet不同于application程序:
import?java.applet.*;
import?java.awt.*;
import?java.awt.event.*;
public?class?LeapyearTest?extends?Applet?implements?ActionListener{
????Label?result;???//定義一個輸出結果的標簽對象
????TextField?t1;???//定義一個用于輸入年份的文本框
????Button?btn;?//定義一個button對象
????
????int?year;
????boolean?leap;
????
????public?void?init(){
????????result=new?Label("請輸入要判斷的年份:");
????????t1=new?TextField(5);
????????btn=new?Button("判斷");
????????
????????add(t1);
????????add(btn);
????????add(result);
????????
????????btn.addActionListener(this);????//為按鈕注冊事件,事件的監聽者為當前類的對象this
????}
????
????public?void?actionPerformed(ActionEvent?e){
????????year=Integer.parseInt(t1.getText());
????????
????????if((year%4==0)&&(year%100!=0)){
????????????leap=true;
????????}else?if(year%400==0){
????????????leap=true;
????????}else{
????????????leap=false;
????????}
????????
????????if(leap==true){
????????????result.setText("你輸入的年份為閏年!");
????????}else{
????????????result.setText("你輸入的年份不是閏年!");
????????}
????????
????????t1.setText("");
????}
}
這里有幾點需要說明的:
1,applet程序必須引入java.applet.*;
2,使用文本框,按鈕等控件需要引入java.awt.*;
3,有事件發生則要引入java.awt.event.*;
4,在類名后加上extends Applet Implements ActionListener
5,添加事件后,當事件被激活后會自動調用actionPerformed函數執行.因此應該為事件寫該函數.