java经典程序及常见算法

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1、if((year%4==0&&year%100!=0)

2、

3、(year%400==0))System.out.println(year+"年是闰年。");elseSystem.out.println(year+"年不是闰年。");}----classCircle{//定义父类--园类privatedoubleradius;//成员变量--园半径Circle(){//构造方法radius=0.0;}Circle(doubler){//构造方法radius=r;}doublegetPerimeter(){//成员方法--求园周长return2*Math.PI*radius;}doublegetAr

4、ea(){//成员方法--求园面积returnMath.PI*radius*radius;}voiddisp(){//成员方法--显示园半径、周长、面积System.out.println("园半径="+radius);System.out.println("园周长="+getPerimeter());System.out.println("园面积="+getArea());}}classCylinderextendsCircle{//定义子类--圆柱类privatedoublehight;//成员变量--园柱高Cylinder(doubler,doubleh){//构造方法super(r)

5、;hight=h;}publicdoublegetVol(){//成员方法--求园柱体积returngetArea()*hight;}publicvoiddispVol(){//成员方法--显示园柱体积System.out.println("圆柱体积="+getVol());}}publicclassTestCylinder{//定义主类publicstaticvoidmain(String[]args){//主程入口CircleCi=newCircle(10.0);//生成园类实例Ci.disp();//调用园类的方法CylinderCyl=newCylinder(5.0,10.0);//

6、生成圆柱类实例Cyl.disp();//调用父类方法Cyl.dispVol();//调用子类方法}}------BufferedReaderstrin=newBufferedReader(newInputStreamReader(System.in));----------FileInputStreamfileIn=newFileInputStream("e:/myjava/Hello.java");intbytes=fileIn.read(buf,0,2056);Stringstr=newString(buf,0,bytes);System.out.println(str);-------

7、---------------------------------publicclassIODemo{publicstaticvoidmain(Stringargs[]){intdata[]={100,101,102,103,104,105};intt;try{DataOutputStreamout=newDataOutputStream(newFileOutputStream(“dest.txt”));for(inti=0;i

8、ream(newFileInputStream(“dest.txt”));for(inti=data.length-1;i>=0;i--){t=in.readInt(data[i]);System.out.print(“”+t);}System.out.println();in.close();}catch(IOExceptione){System.out.println(e.getMessage());}}}-----------------------------------------------------------importjava.awt.Color;importjava.a

9、wt.Graphics;importjavax.swing.JApplet;publicclassMoveMessageextendsJAppletimplementsRunnable{Stringstr;inttime;privateThreadthread;publicvoidinit(){setBackground(Color.PINK);str=getParameter("message");Stri