java基础源代码

1 /******************************************
2 * 这是演示JAVA应用程序结构的一个简单例子 *
3 * 该文件名是 Welcome.java *
4 ******************************************/
5 class Welcome
6 {
7 public static void main(String[] args)
8 {
9 System.out.println("欢迎使用JAVA编程！"); //显示“欢迎使用JAVA编程！”
10 }
11 }
**********************************************************
// exp1_2.java
class exp1_2
{
public static void main(String[] args)
{
int n; //声明一个名为n的整型变量
n=15; //给变量赋15
System.out.println(n); //在屏幕上显示变量n的值
//在屏幕上显示一个字符串及n的平方值
System.out.println("n的平方值是："+n*n);
}
}

*********************************************************************
class exp_string
{
public static void main(String[] args)
{
System.out.println("wn\u04305f\\\nu0x\ty");
System.out.println("----------------------");
System.out.println("b\bt\"\u007g\\u0042\tr\nn\u0630j");
}
}
*******************************************************************
class exp_char_num
{
public static void main(String[] args)
{
System.out.println("'A'+1="+('A'+1));
System.out.println("'1'+1="+('1'+1));
System.out.println("1+1="+(1+1));
}
}

*********************************************************************
class exp_operater
{
public static void main(String[] args)
{
int a=63, b=48;
double i=3.1415, j=4.11;
System.out.println("a+b="+(a+b));
System.out.println("a-b="+(a-b));
System.out.println("a*b="+(a*b));
System.out.println("a/b="+(a/b));
System.out.println("a%b="+(a%b));
System.out.println("i+j="+(i+j));
System.out.println("i-j="+(i-j));
System.out.println("i*j="+(i*j));
System.out.println("i/j="+(i/j));
System.out.println("i%j="+(i%j));
System.out.println("a+j="+(a+j));
System.out.println("i*b="+(i*b));
System.out.println("字母A的后继字母是"+(char)('A'+1));
}
}

********************************************************************
//"System.in.read()"练习
package in_out;
//import java.io.*;
public class Program
{
public static void main(String[] args)throws java.io.IOException
{
//基本演示
char ch;
System.out.print("请输入一个字符:\t");
ch = (char)System.in.read();
System.out.println("您输入的字符是:\t" + ch);

//演示int、ctrl+z
//int i;
//System.out.print("请输入一个字符:\t");
//i= System.in.read();
//System.out.println("您输入的字符是:\t" + i);

//演示键盘输入与缓冲区
//char ch1,ch2,ch3,ch4,c

h5;
//System.out.print("请输入一行字符(至少5个):\t");
//ch1= (char)System.in.read();
//ch2= (char)System.in.read();
//ch3= (char)System.in.read();
//ch4= (char)System.in.read();
//ch5= (char)System.in.read();
//System.out.println("您输入的一行字符中,前5个字符是:\t" + ch1 + "," + ch2 + "," + ch3 + "," + ch4 + "," +ch5);
//System.out.println("您输入的一行字符中,前5个字符的代码是:\t" + (int)ch1 + "," + (int)ch2 + "," + (int)ch3 +","+(int)ch4 +","+(int)ch5);
}
}


############################################################################
//表达式与类"MATH"练习;
import java.io.*;
/**
* Summary description for Program
*/
public class Program
{
public static void main(String[] args)throws java.io.IOException
{
int i, j;
i = 1;
j = i + 1;
System.out.println("i="+i);
System.out.println("j="+j);
//System.out.println("j="+(j=i+j));
//System.out.println("j="+j);

int a, b, c;
long l=3;
a = 1;
b = 2;
c = l + 1; //将出错!
c = (int)(l + 1);
System.out.println("a=" + a + "\tb=" + b+"\tc=" + c);
System.out.println(a=b=3+4);
System.out.println("a=" + a + "\tb=" + b+"\tc=" + c);
//System.out.println(a=1+(b=2+(c=3+4)));
//System.out.println("a=" + a + "\tb=" + b+"\tc=" + c);

byte b1=42;
System.out.println("b1="+b1+"\t~b1="+~b1);
System.out.println("b1<<2 ="+(b1<<2));
System.out.println("b1>>2 ="+(b1>>2));

byte b2=-42;
System.out.println("b2>>2 ="+(b2>>2));
System.out.println("b2>>>2 ="+(b2>>>2)); //注意：结果取int类型
System.out.println("b1>>>2 ="+(b1>>>2));

byte b3=15;
System.out.println("b1&b3 ="+(b1&b3));

System.out.println("b1|b3 ="+(b1|b3));

System.out.println("b1^b3 ="+(b1^b3));

int x1=1,y1;
y1=++x1;
System.out.println("y1="+y1+"\tx1="+x1);

int x2=1,y2;
y2=x2++;
System.out.println("y2="+y2+"\tx2="+x2);

int n=1,m=2,max;
System.out.println("max="+(max=n>m?n:m));

System.out.println(" '6'-48="+('6'-48));
System.out.println(" '6'^48="+('6'^48));
System.out.println(" '6'&~48="+('6'&~48));

double xx = 2.0, yy = 3.0, z;
System.out.println("xx="+xx+"\tyy=+yy);
System.out.println("xx-yy的绝对值是:" + Math.abs(xx - yy));
System.out.println("xx的yy次方是:" + Math.pow(xx, yy));
z = Math.sqrt(yy);
System.out.println("yy的平方根是:" + z);
System.out.println("第一次产生的随机数是:" + Math.random());
System.out.println("第二次产生的随机数是:" + Math.random());

}
}

##################################################################

//数值输入练习;
import java.io.*;
/**
* Summary description for Program
*/
public class Program1
{
public static void main(String[] args)throws java.io.IOException
{
BufferedReader din = new BufferedReader(new InputStreamReader
(System.in));
String input;
int i,ii;

float f,ff;

System.out.println("请输入一个整数：");
input = din.readLine();
i = Integer.valueOf(input).intValue();
ii=i*2;

System.out.println("请输入一个实数：");
input = din.readLine();
f = Float.valueOf(input).floatValue();
ff=f*2;

System.out.println("您输入的整数×2的值是:" + ii);
System.out.println("您输入的实数×2的值是:" + ff);

}
}
##############################################################################


//FahToCal.java
import java.io.*;
public class FahToCal
{
public static void main(String[] args)throws IOException
{
BufferedReader din = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入一个华氏温度值：");
String input = din.readLine();
double fahrenheit= Double.valueOf(input).doubleValue();
double celsius=（fahrenheit -32.0）*5.0/9.0;
System.out.println("celsius="+ celsius);
}
}

###########################################################


//IfTest1.java
import java.io.*;
public class IfTest1
{
public static void main(String[] args)throws IOException
{
BufferedReader din = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入第一个实数：");
String input = din.readLine();
double a= Double.valueOf(input).doubleValue();
System.out.println("请输入第二个实数：");
String input = din.readLine();
double b= Double.valueOf(input).doubleValue();
double max=a;
if（amax=b;
max*=max;
System.out.println("其中较大数的平方是:"+ max);
}
}

#############################################################

//IfTest2.java
import java.io.*;
public class IfTest2
{
public static void main(String[] args)throws IOException
{
char response
System.out.println("DO you like programming？（Y/N）：");
response=(char)System.in.read();
if(response=='Y')
System.out.println("Just wait until you see what you can do！");
if(response=='N')
{ System.out.println("Keep trying！I bet you’ll change your mind.");
System.out.println("Programming can be a blast!");
}
}
}

###########################################################

//IfElseTest1.java
import java.io.*;
public class IfElseTest1
{
public static void main(String[] args)throws IOException
{
char response
System.out.println("DO you like programming？（Y/N）：");
response=(char)System.in.read();
if(response=='Y')
System.out.println("Just wait until you see what you can do！");
else
{ System.out.println("Keep trying！I bet you’ll change your mind.");
System.out.println("Programming can be a blast!");
}
}
}


#############################################################
//IfElseTest2.java
import java.io.*;
public class IfElseTest2
{
public static void main(Stri

ng[] args)throws IOException
{
BufferedReader din = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入一个百分制成绩：");
String input = din.readLine();
double grade= Double.valueOf(input).doubleValue();
if(grade>=90)
System.out.println("该成绩优秀:A");
else if(grade>=80)
System.out.println("该成绩良好:B ");
else if(grade>=70)
System.out.println("该成绩中等:C");
else if(grade>=60)
System.out.println("该成绩及格:D");
else
System.out.println("该成绩不及格:E ");
}
}

#################################################################################

//Switch1.java
import java.io.*;
public class Switch1
{
public static void main(String[] args)throws IOException
{
Char ch；
System.out.println("请输入一个字符（m或h或n）：");
ch=(char)System.in.read();
switch(ch)
{
Case 'm': System.out.println("Good morning！");
Case 'h': System.out.println("Hello！");
Case 'n': System.out.println("Good night！");
default : System.out.println("I can’t understand it.");
}
System.out.println("Bye！");
}
}


####################################################################

//Switch2.java
import java.io.*;
public class Switch2
{
public static void main(String[] args)throws IOException
{
Char ch；
System.out.println("请输入一个字符（m或h或n）：");
ch=(char)System.in.read();
switch(ch)
{
Case 'm': System.out.println("Good morning!");break；
Case 'h': System.out.println("Hello!");break；
Case 'n': System.out.println("Good night!");break；
default : System.out.println("I can’t understand it.");
}
System.out.println("Bye!");
}
}

###############################################################################

import java.io.*;
public class Switch3
{
public static void main(String[] args)throws IOException
{
BufferedReader din = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入一个百分制成绩：");
String input = din.readLine();
int score= Integer.valueOf(input).intValue();
char grade;
switch(score/10)
{
Case 10:;
Case 9: grade='A';break;
Case 8: grade='B';break;
Case 7: grade='C';break;
Case 6: grade='D';break;
Case 5: ;
Case 4: ;
Case 3: ;
Case 2: ;
Case 1: ;
Case 0: grade='E';break;
default: grade='F';
}
if(grade<'F')
System.out.println("其等级分为："+ grade);
else
System.out.println("输入数据有错误！");
}
}

#####################################################################################

//While1.java
import java.io.*;
public class While1
{
public static void main(String[] args)throws IOException
{

int

countr=0;
while(counter<100)
{
counter++;
System.out.println(counter+"\t");
}
}
}

########################################################################################

//While2.java
import java.io.*;
public class While2
{
public static void main(String[] args)throws IOException
{
int i=0,sum=0;
while(i<=100)
{
sum+=i;
i++;
}
System.out.println("sum="+sum);

}
}

###################################################################################

//While3.java
import java.io.*;
public class While3
{
public static void main(String[] args)throws IOException
{
int c=0; //变量c用于记录输入字符个数的计数器，其初植为0。
char ch;
while((ch=(char)System.in.read())!='\n')
{
if((ch>='A'&&ch<='Z')||(ch>='a'&&ch<='z'))
c++;
}
System.out.println("其中字母的个数为:"+c);
}
}

###################################
//While4.java
import java.io.*;
public class While4
{
public static void main(String[] args)throws IOException
{
int i=1;
int sum=0;
int j;
int fact;
while(i<=10)
{
fact=1;
j=1;
while(j<=i)
{
fact*=j;
j++;
}
sum+=fact;
i++;
}
System.out.println("1！+2！+…+10！="+sum);
}
}
###########################################################

//While5.java
import java.io.*;
public class While5
{ public static void main(String[] args)throws IOException
{
int i=1;
int sum=0;
int fact=1;
while(i<=10)
{ fact*=i;
sum+=fact;
i++;
}
System.out.println("1！+2！+…+10！="+sum);
}
}

############################################################3
//While6.java
import java.io.*;
public class While6
{ public static void main(String[] args)throws IOException
{
int f1=1;
int f2=1;
int i=1;
while(i<=12) //总共循环12次，循环体每次产生两个数。
{
if(i%4) System.out.println(); //输出一空行。功能同println(“\n”)。
System.out.println("\t"+f1+"\t"+f2);
f1=f1+f2;
f2=f1+f2;
i++;
}
}
}


#############################################
//While7.java
import java.io.*;
public class While7
{
public static void main(String[] args)throws IOException
{
int day=0,buy=2;
float sum=0.0,ave;
while(buy<=100)
{
sum+=0.8*buy;
day++;
buy*=2;
}
ave=sum/day;
System.out.println("每天平均花钱是："+ ave+"元");
}
}


############################################
//DoWhile2.java
import java.io.*;
public class DoWhile2
{
public static void main(String[] args)throws IOException
{
BufferedReader din = new BufferedReader(new InputStreamReader(System.in));
String password = din.readLine();
do{
Sys

tem.out.println("请输入您的口令：");
String password = din.readLine();
}while(!password.equals("8888"));
System.out.println("欢迎您进入本应用系统！");
//......
}
}

##################################################

//For2.java
import java.io.*;
public class For2
{ public static void main(String[] args)throws IOException
{
int c=0; //变量c用于记录输入字符个数的计数器，其初植为0。
char ch;
for(;(ch=(char)System.in.read())!='\n';)
if((ch>='A'&&ch<='Z)||(ch>='a'&&ch<='z'))c++;
System.out.println("其中字母的个数为:"+c);
}
}

###################################################

//Break1.java
import java.io.*;
public class Break1
{
public static void main(String[] args)throws IOException
{
int i,n;
BufferedReader din = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入一个整数：");
n= Integer.valueOf(din.readLine()).intValue();
for(i=2;iif(n%i==0)break；
if(ielse System.out.println(n+"非质数！");
}
}

##############################################
//Contiune.java
import java.io.*;
public class Contiune
{
public static void main(String[] args)throws IOException
{
int i,sum=0;
for(i=1;i<100;i++)
{
if(i%2==0) contiune;
sum+=i;
}
System.out.println("1+3+5+……+99="+sum);
}
}

################################################

class Car //定义类“汽车”
{
String brand; //声明成员“品牌”
int gas; //声明成员“油量”
void set(String vbrand, int vgas) //声明方法“汽车设置”
{
brand= vbrand ;
gas= vgas;
}
void run() //声明方法“行驶”
{
if(gas>0)
gas-=10;
else
System.out.println("没油了!不能再跑了……");
}
void disp() //声明方法“显示汽车的信息”
{
System.out.println("品牌:"+brand+"\t油量:"+gas);
}
}
public class Program //定义“主类”
{
public static void main(String[] arg)
{
Car MyCar=new Car(); //创建类Car的一个对象，对象名为MyCar
MyCar. set("红旗",10); //调用对象MyCar的方法set()
MyCar. disp(); //调用对象MyCar的方法disp()
MyCar. run(); //调用对象MyCar的方法run()
System.out.println("汽车正在行驶中……");//调用对象System.out的方法println ()
MyCar. run();
}
}

########################################

package 英语短文字母统计;

import java.io.*;
public class CreatFile
{
public static void main(String args[]) throws IOException
{
int ch;
FileOutputStream out1 = new FileOutputStream("exp901.out");
System.out.println("请键盘输入一篇英语短文:");
while ((ch = System.in.read()) != -1)
out1.write(ch);
out1.close();

byte [] c = new byte [

26];
FileInputStream in1 = new FileInputStream("exp901.out");
FileOutputStream out2 = new FileOutputStream("exp902.out");
while ((ch = in1.read()) != -1)
if (ch >= 97)c[ch - 97]++;
out2.write(c);
out2.close();
in1.close ();

FileInputStream in2 = new FileInputStream("exp902.out");
System.out.println("其中各字母出现次数的统计结果为:");
while ((ch = in2.read()) != -1)
System.out.print(ch+",");
System.out.println();
in2.close();
System.in.read();
}
}

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