java速度入四.文件的基本操作及猜数字游戏的实现

1.文件操作。

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.util.Date;

public class fileOperator {

private static String filePath="txt.txt";

private static File file=new File(filePath);

private static int runCount=0;

private static String date=String.format("%tF %<tT", new Date());

private static String os=System.getProperty("os.name");

private static String dataStr="";

public static void main(String args[])

{

loadConfig();

if(dataStr.isEmpty()) System.out.println("First run!");

else

{

System.out.println("runCount: "+runCount+"  date:"+date+" os: "+os);

}

putConfig() ;

System.out.println("Hello,java!");

}

private static void loadConfig()

{

try

{

if(!file.exists()) file.createNewFile();

byte[] data=new byte[64];

FileInputStream fis=new FileInputStream(file);

int rs=0;

while((rs=fis.read(data))>0) dataStr+=new String(data,0,rs);

if(!dataStr.isEmpty())

{

String[] sets=dataStr.split(",");

runCount=Integer.parseInt(sets[0]);

date=sets[1];

os=sets[2];

}

fis.close();

}catch(Exception e)

{e.printStackTrace();}

}

private static void putConfig()

{

//String dataStr;

try

{

if(!file.exists()) file.createNewFile();

dataStr=(runCount+1)+","+date+","+os;

byte[] data=dataStr.getBytes();

FileOutputStream fout=new FileOutputStream(file);

fout.write(data);

fout.flush();

fout.close();

}catch(Exception e)

{

e.printStackTrace();

}

}

}

一个简单的文件操作，将系统信息写入到一个文本文件。
2.猜数字游戏

import java.util.Scanner;
public class guessNumber {
public static void main(String[]args)
{
int ans=(int)(Math.random()*10);
int num,i=0;
System.out.println("Guess a number with a boundary between 1 to 100:");
Scanner input =new Scanner(System.in);
for(i=1;i<=5;i++)
{

System.out.println("Input Number:");
num=input.nextInt();
if(ans==num) break;
if(ans<num)
{
System.out.println("Too big!");
System.out.println("You have only "+(5-i)+" chances!");
continue;
}
if(ans>num)
{
System.out.println("So small!");
System.out.println("You have only "+(5-i)+" chances!");

}

}
if(i<=5) System.out.println("Congratulations!");
else System.out.println("You need more practise and never give up!");
}
}
最简单的实现，未加判断什么的。