一些入門的java小程序xxjss一個簡單的Java應用程序public class Hello{ public static void main (String args[ ]) { System.out.println('這是一個簡單的應用程序'); }}源程序public class People{ float hight,weight; String head,ear,mouth; void speak(String s) { System.out.println(s); }}class A{ public static void main(String args[]) { People zhubajie; zhubajie=new People(); zhubajie.weight=200f; zhubajie.hight=1.70F; zhubajie.head='大頭'; zhubajie.ear='兩只大耳朵'; zhubajie.mouth='一只大嘴'; System.out.println('重量'+zhubajie.weight+'身高' +zhubajie.hight); System.out.println(zhubajie.head+zhubajie.mouth+zhubajie.ear); zhubajie.speak('師傅，咱們別去西天了，改去月宮吧'); }}一個簡單的Java小應用程序（Java Applet）import java.applet.*; import java.awt.*;public class boy extends Applet{ public void paint(Graphics g) { g.setColor(Color.red); g.drawString('我一邊喝著咖啡，一邊學Java呢',2,30); g.setColor(Color.blue); g.drawString('我學得很認真',10,50); }} 基本數據類型和數組例子1public class Example2_1 { public static void main (String args[ ]) { char chinaWord='你',japanWord='ぁ'; int p1=20328,p2=12358; System.out.println('漢字'你'字在unicode表中的順序位置:'+(int)chinaWord); System.out.println('日語'ぁ'字在unicode表中的順序位置:'+(int)japanWord); System.out.println('unicode表中第20328位置上的字符是:'+(char)p1); System.out.println('unicode表中第12358位置上的字符是:'+(char)p2); }}例子2 public class Example2_2{ public static void main (String args[ ]) { byte a=120; short b=255; int c=2200; long d=8000; float f; double g=123456789.123456789; b=a; c=(int)d; f=(float)g; //導致精度的損失. System.out.print('a= '+a); System.out.println(' b= '+b); System.out.print(' c= '+c); System.out.println(' d= '+d); System.out.println('f= '+f); System.out.println('g= '+g); }}例子3 public class Example2_3{ public static void main(String args[]) { int a[]={1,2,3,4}; int b[]; System.out.println(a[3]); b=a; b[3]=100; System.out.println(a[3]); System.out.println(b[3]); }} 運行結果：4100100運算符、表達式和語句例子1class Example3_1{ public static void main(String args[]) { char a1='十',a2='點',a3='進',a4='攻'; char secret='8'; a1=(char)(a1^secret); a2=(char)(a2^secret); a3=(char)(a3^secret); a4=(char)(a4^secret); System.out.println('密文:'+a1+a2+a3+a4); a1=(char)(a1^secret); a2=(char)(a2^secret); a3=(char)(a3^secret); a4=(char)(a4^secret); System.out.println('原文:'+a1+a2+a3+a4); }}例子2class Example3_2{ public static void main(String args[]) { float x=12.56f,y; if(x0&&x