java程序代码.docx
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java程序代码
第一章Java语言入门
例子1
publicclassHello
{
publicstaticvoidmain(Stringargs[])
{
System.out.println("你好,很高兴学习Java");
}
}
例子2
publicclassPeople
{intheight;
Stringear;
voidspeak(Strings)
{System.out.println(s);
}
}
classA
{publicstaticvoidmain(Stringargs[])
{Peoplezhubajie;
zhubajie=newPeople();
zhubajie.height=170;
zhubajie.ear="两只大耳朵";
System.out.println("身高:
"+zhubajie.height);
System.out.println(zhubajie.ear);
zhubajie.speak("师傅,咱们别去西天了,改去月宫吧");
}
}
例子3
importjava.applet.*;
importjava.awt.*;
publicclassBoyextendsApplet
{publicvoidpaint(Graphicsg)
{g.setColor(Color.red);
g.drawString("我一边喝着咖啡,一边学Java呢",5,30);
g.setColor(Color.blue);
g.drawString("我学得很认真",10,50);
}
}
第二章标识符、关键字和数据类型
例子1
publicclassExample2_1
{publicstaticvoidmain(Stringargs[])
{charchinaWord='你',japanWord='ぁ';
intp1=36328,p2=38358;
System.out.println("汉字\'你\'在unicode表中的顺序位置:
"+(int)chinaWord);
System.out.println("日语\'ぁ\'在unicode表中的顺序位置:
"+(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
publicclassExample2_2
{publicstaticvoidmain(Stringargs[])
{intc=2200;
longd=8000;
floatf;
doubleg=123456789.123456789;
c=(int)d;
f=(float)g;//导致精度的损失.
System.out.print("c="+c);
System.out.println("d="+d);
System.out.println("f="+f);
System.out.println("g="+g);
}
}
例子2.5
importjava.util.Scanner;
publicclassTest
{
publicstaticvoidmain(Stringargs[])
{
System.out.println("请输入若干个数,每输入一个数回车确认");
System.out.println("最后输入数字0结束输入操作");
Scannerreader=newScanner(System.in);
doublesum=0;
doublex=reader.nextDouble();
while(x!
=0)
{
sum=sum+x;
x=reader.nextDouble();
}
System.out.println("这几个数的和为sum="+sum);
}
}
例子3
publicclassExample2_3
{publicstaticvoidmain(Stringargs[])
{inta[]={100,200,300};
intb[]={10,11,12,13,14,15,16};
b=a;
b[0]=123456;
System.out.println("数组a:
"+a[0]+","+a[1]+","+a[2]);
System.out.println("数组b:
"+b[0]+","+b[1]+","+b[2]);
System.out.println("数组b的长度:
"+b.length);
}
}
第三章运算符、表达式和语句
例子1
classExample3_1
{publicstaticvoidmain(Stringargs[])
{chara1='十',a2='点',a3='进',a4='攻';
charsecret='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2
classExample3_2
{publicstaticvoidmain(Stringargs[])
{intx,y=10;
if(((x=0)==0)||((y=20)==20))
{System.out.println("现在y的值是:
"+y);
}
inta,b=10;
if(((a=0)==0)|((b=20)==20))
{System.out.println("现在b的值是:
"+b);
}
}
}
例子3
publicclassExample3_3
{publicstaticvoidmain(Stringargs[])
{inta=9,b=5,c=7,t;
if(a>b)
{t=a;a=b;b=t;
}
if(a>c)
{t=a;a=c;c=t;
}
if(b>c)
{t=b;b=c;c=t;
}
System.out.println("a="+a+",b="+b+",c="+c);
}
}
例子4
publicclassExample3_4
{publicstaticvoidmain(Stringargs[])
{intmath=65,english=85;
if(math>60)
{System.out.println("数学及格了");
}
else
{System.out.println("数学不及格");
}
if(english>90)
{System.out.println("英语是优");
}
else
{System.out.println("英语不是优");
}
System.out.println("我在学习控制语句");
}
}
例子5
publicclassExample3_5
{publicstaticvoidmain(Stringargs[])
{intx=2,y=1;
switch(x+y)
{case1:
System.out.println(x+y);
break;
case3:
System.out.println(x+y);
case0:
System.out.println(x+y);
break;
default:
System.out.println("没有般配的"+(x+y));
}
}
}
例子6
publicclassExample3_6
{publicstaticvoidmain(Stringargs[])
{longsum=0,a=5,item=a,n=10,i=1;
for(i=1;i<=n;i++)
{sum=sum+item;
item=item*10+a;
}
System.out.println(sum);
}
}
例子7
classExample3_7
{publicstaticvoidmain(Stringargs[])
{doublesum=0,a=1;
inti=1;
while(i<=20)
{sum=sum+a;
i=i+1;
a=a*(1.0/i);
}
System.out.println("sum="+sum);
}
}
例子8
classExample3_8
{publicstaticvoidmain(Stringargs[])
{intsum=0,i,j;
for(i=1;i<=10;i++)
{if(i%2==0)//计算1+3+5+7+9
continue;
sum=sum+i;
}
System.out.println("sum="+sum);
for(j=2;j<=50;j++)//求50以内的素数
{for(i=2;i<=j/2;i++)
{if(j%i==0)
break;
}
if(i>j/2)
{System.out.println(""+j+"是素数");
}
}
}
}
第四章类、对象和接口
ClassTrangle
{
DoublesideA,sideB,sideC;
VoidsetSide(doublea,doubleb,doublec)
{
sideA=a;
sideB=b;
sideC=c;
}
DoublegetSideA()
{
ReturnsideA;
}
DoublegetSideB()
{
ReturnsideB;
}
DoublegetSideC()
{
ReturnsideC;
}
BooleanisOrNotTrangle()
{
If(sideA+sideB>sideC&&sideA+sideC>sideB&&sideB+sideC>sideA)
{
Returntrue;
}
Else
{
Returnfalse;
}
}
}
例子1
classXiyoujiRenwu
{floatheight,weight;
Stringhead,ear,hand,foot,mouth;
voidspeak(Strings)
{System.out.println(s);
}
}
classA
{publicstaticvoidmain(Stringargs[])
{XiyoujiRenwuzhubajie;//声明对象
zhubajie=newXiyoujiRenwu();//为对象分配内存,使用new运算符和默认的构造方法
}
}
例子2
classPoint
{intx,y;
Point(inta,intb)
{x=a;
y=b;
}
}
publicclassA
{publicstaticvoidmain(Stringargs[])
{Pointp1,p2;//声明对象p1和p2
p1=newPoint(10,10);//为对象分配内存,使用new和类中的构造方法
p2=newPoint(23,35);//为对象分配内存,使用new和类中的构造方法
}
}
例子3
classXiyoujiRenwu
{floatheight,weight;
Stringhead,ear,hand,foot,mouth;
voidspeak(Strings)
{head="歪着头";
System.out.println(s);
}
}
classExample4_3
{publicstaticvoidmain(Stringargs[])
{XiyoujiRenwuzhubajie,sunwukong;//声明对象
zhubajie=newXiyoujiRenwu();//为对象分配内存
sunwukong=newXiyoujiRenwu();
zhubajie.height=1.80f;//对象给自己的变量赋值
zhubajie.head="大头";
zhubajie.ear="一双大耳朵";
sunwukong.height=1.62f;//对象给自己的变量赋值
sunwukong.weight=1000f;
sunwukong.head="绣发飘飘";
System.out.println("zhubajie的身高:
"+zhubajie.height);
System.out.println("zhubajie的头:
"+zhubajie.head);
System.out.println("sunwukong的重量:
"+sunwukong.weight);
System.out.println("sunwukong的头:
"+sunwukong.head);
zhubajie.speak("俺老猪我想娶媳妇");//对象调用方法
System.out.println("zhubajie现在的头:
"+zhubajie.head);
sunwukong.speak("老孙我重1000斤,我想骗八戒背我");//对象调用方法
System.out.println("sunwukong现在的头:
"+sunwukong.head);
}
}
例子4
class梯形
{float上底,下底,高,面积;
梯形(floatx,floaty,floath)
{上底=x;
下底=y;
高=h;
}
float计算面积()
{面积=(上底+下底)*高/2.0f;
return面积;
}
void修改高(floatheight)
{高=height;
}
float获取高()
{return高;
}
}
publicclassExample4
{publicstaticvoidmain(Stringargs[])
{梯形laderOne=new梯形(12.0f,3.5f,50),laderTwo=new梯形(2.67f,3.0f,10);
System.out.println("laderOne的高是:
"+laderOne.获取高());
System.out.println("laderTwo的高是:
"+laderTwo.获取高());
System.out.println("laderOne的面积是:
"+laderOne.计算面积());
System.out.println("laderTwo的面积是:
"+laderTwo.计算面积());
laderOne.修改高(10);
floath=laderOne.获取高();
laderTwo.修改高(h*2);
System.out.println("laderOne现在的高是:
"+laderOne.获取高());
System.out.println("laderTwo现在的高是:
"+laderTwo.获取高());
System.out.println("laderOne现在的面积是:
"+laderOne.计算面积());
System.out.println("laderTwo现在的面积是:
"+laderTwo.计算面积());
}
}
例子5
classPeople
{Stringface;
voidsetFace(Strings)
{face=s;
}
}
classA
{voidf(intx,doubley,Peoplep)
{x=x+1;
y=y+1;
p.setFace("笑脸");
System.out.println("参数x和y的值分别是:
"+x+","+y);
System.out.println("参数对象p的face是:
"+p.face);
}
}
publicclassExample4_5
{publicstaticvoidmain(Stringargs[])
{intx=100;
doubley=100.88;
Peoplezhang=newPeople();
zhang.setFace("很严肃的样子");
Aa=newA();
a.f(x,y,zhang);
System.out.println("main方法中x和y的值仍然分别是:
"+x+","+y);
System.out.println("main方法中对象zhang的face是:
"+zhang.face);
}
}
例子6
class圆
{double半径;
圆(doubler)
{半径=r;
}
double计算面积()
{return3.14*半径*半径;
}
void修改半径(double新半径)
{半径=新半径;
}
double获取半径()
{return半径;
}
}
class圆锥
{圆底圆;
double高;
圆锥(圆circle,doubleh)
{this.底圆=circle;
this.高=h;
}
double计算体积()
{doublevolume;
volume=底圆.计算面积()*高/3.0;
returnvolume;
}
void修改底圆半径(doubler)
{底圆.修改半径(r);
}
double获取底圆半径()
{return底圆.获取半径();
}
}
classExample4_6
{publicstaticvoidmain(Stringargs[])
{圆circle=new圆(10);
圆锥circular=new圆锥(circle,20);
System.out.println("圆锥底圆半径:
"+circular.获取底圆半径());
System.out.println("圆锥的体积:
"+circular.计算体积());
circular.修改底圆半径(100);
System.out.println("圆锥底圆半径:
"+circular.获取底圆半径());
System.out.println("圆锥的体积:
"+circular.计算体积());
}
}
可变参数例子:
classA
{
publicdoublef(doublea,int...x)
{
doubleresult=0;
intsum=0;
for(inti=0;i{
sum=sum+x[i];
}
result=a*sum;
returnresult;
}
}
publicclassExample
{
publicstaticvoidmain(Stringargs[])
{
Aa=newA();
doubleresult=a.f(1.28,10,20,30);
System.out.println(result);
result=a.f(62.0629,-1,-2,-3,-4,-5,-6);
System.out.println(result);
}
}
例子7
class梯形
{float上底,高;
staticfloat下底;
梯形(floatx,floaty,floath)
{上底=x;下底=y;高=h;
}
float获取下底()
{return下底;
}
void修改下底(floatb)
{下底=b;
}
}
classExample4_7
{publicstaticvoidmain(Stringargs[])
{梯形laderOne=new梯形(3.0f,10.0f,20),laderTwo=new梯形(2.0f,3.0f,10);
梯形.下底=200;//通过类名操作类变量
System.out.println("laderOne的下底:
"+laderOne.获取下底());
System.out.println("laderTwo的下底:
"+laderTwo.获取下底());
laderTwo.修改下底(60);//通过对象操作类变量
System.out.println("laderOne的下底:
"+laderOne.获取下底());
System.out.println("laderTwo的下底:
"+laderTwo.获取下底());
}
}
例子8
classFibi
{publicstaticlongfibinacii(intn)
{longc=0;
if(n==1||n==2)
c=1;
else
c=fibinacii(n-1)+fibinacii(n-2);
returnc;
}
}
publiccla