test2.java

来自「多线程编程 一个线程计算完全数和一个线程计算水仙花数 IO流 以及图形界面」· Java 代码 · 共 61 行

import java.io.*;
 class xfile
{
	private String filename;
	public xfile(String filename)
	{
		this.filename=filename;	
	}
	
	public void writetofile() throws IOException
	{
		FileOutputStream fout=new FileOutputStream(this.filename);
		DataOutputStream dout=new DataOutputStream(fout);
		for(int i=1;i<=1000;i++)
		{
			double x=Math.sqrt(i);
			int j;
			for(j=2;j<=x;j++)
			{
				if(i%j==0)
				break;
			}
			if(j>x)
			{
				dout.writeInt(i);
			}
		}
		dout.close();
		fout.close();
		System.out.println("Write to file"+this.filename);
	}
	
	public void readfromfile() throws IOException
	{
		FileInputStream fin=new FileInputStream(this.filename);
		DataInputStream din=new DataInputStream(fin);
		System.out.println("read from file"+this.filename);
		while(true)
		{
			try
			{
				int i=din.readInt();
				System.out.print(i+" ");
			}
			catch(EOFException eof)
			{
				break;
			}
		}
		System.out.println();
		din.close();
		fin.close();
	}
	
	public static void main(String[] args)throws Exception
	{
		xfile a=new xfile("file.dat");
		a.writetofile();
		a.readfromfile();
	}
}