import java.io.*;
import java.util.Random;
public class Exer6_4
{
public static void UseFileWriter() throws IOException
{
String fileName="d:\\testTime.txt"; //将文件保存到d盘根目录下
FileWriter writer = new FileWriter(fileName);
//如果改为 FileWriter writer = new
FileWriter(fileName,true);则代表追加到文件中
Random ran=new java.util.Random(); //生命一个随机数对象
Double j=ran.nextDouble(); // 得到下一个随机数
for(long i=0;i<100000;i++)
{
j=ran.nextDouble();
writer.write(j.toString()+"\n"); //将随机数写入流
}
writer.close(); //关闭流
}
public static void UserBufferedWtriter() throws IOException
{ //当需要写入大量内容 此方法效率高
String fileName="d:/testTime.txt"; //将文件保存到d盘根目录下
BufferedWriter out=new BufferedWriter(new
FileWriter(fileName));
//将FileWrite嵌套在BufferedWriter中
Random ran=new java.util.Random(); //生命一个随机数对象
Double j=ran.nextDouble(); // 得到下一个随机数
for(long i=0;i<100000;i++)
{
j=ran.nextDouble();
out.write(j.toString()); //将随机数写入流
out.newLine();
}
out.close(); //关闭流
}
public static void main(String args[]) throws IOException
{
// UseFileWriter();
UserBufferedWtriter();
}
}
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import java.io.*;
public class Exer6_7 {
//从键盘读入一组字符并返回
public static String Keyboard()
{
BufferedReader InputStream = new BufferedReader(new
InputStreamReader(System.in));
try
{
return(InputStream.readLine());
}
catch (IOException e){return "Error occur when input from
Keyboard!";}
}
//将一组字符存入文件
public static void PuttoFile(String s,String fileName)
{
//String fileName="d:\\testInput.txt";
try
{
FileWriter writer = new FileWriter(fileName);
writer.write(s); //将随机数写入流
writer.close(); //关闭流
}
catch (IOException iox)
{
System.out.println("Error occur when PuttoFile!");
}
}
//将数据从文件中读取出来
public static String GetFromFile(String fileName)
{
String s="";
//String fileName="d:/testInput.txt";
try
{
BufferedReader in = new BufferedReader(new
FileReader(fileName));
s=in.readLine(); //读取一串字符保存到s
}
catch(IOException io)
{
System.out.println("Error occur when GetFromFile!");
}
return s;
}
//将一组字符排序(冒泡排序 升序排序) 并将排序后的字符串返回
public static String sort(String s)
{
char[] c=s.toCharArray(); //将字符串转换成字符数组
char temp; //排序用到的临时变量
for(int i=0;i
for(int j=i+1;j
if(c[i]>c[j])
{
temp=c[i];
c[i]=c[j];
c[j]=temp;
}
s=new String(c); //注意 不能用c.toString
return s;
}
public static void main(String args[]){
String s=Keyboard(); //从键盘输入一组字符
PuttoFile(s,"d:\\testInput.txt"); //将字符保存到 d:\testInput.txt
s=GetFromFile("d:/testInput.txt"); //从文件d:\testInput.txt读出数据
s=sort(s); //将s进行排序
PuttoFile(s,"d:\\testOutput.txt"); //将排序后的内容保存到
d:\testOutput.txt
System.out.println(s); //将排序后的内容输出到屏幕上
}
}
