new 是否创建了一个文件

package Download;

import java.io.File;
package Download;

import java.io.*;

public class hello {
	public static void main(String args[]) throws FileNotFoundException{
		System.out.println("hello");
		
		new download(1,0,"aaa").start();
		new download(2,3,"bbb").start();
		new download(3,6,"ccc").start();
	
	}
}
class download extends Thread{
	protected int ID;
	protected int start;
	protected String str;
	public download(int ID,int start ,String string) {
		this.ID=ID;
		this.start=start;
		this.str=string;
	}
	public void run(){
		System.out.println(str);
		try {
			Thread.sleep(ID*2000);
		} catch (InterruptedException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		try {
			
			//只new一个文件---------------------------------------------------------
			File fileA =new File("aaa.txt");
			
			//new一个文件，并写入数据------------------------------------------------
			File fileB =new File("bbb.txt");
			if(fileB.exists()){
				FileInputStream fis=new FileInputStream(fileB);
				byte b[]=new byte[1024];
				int len=0;
				while((len=fis.read(b))!=-1){
					String temp=new String(b);
					System.out.println(temp);
				}
				fis.close();
			}
			
			
			FileOutputStream fos=new FileOutputStream(fileB);
			fos.write(str.getBytes(),0,str.length());
			fos.close();
			
			//new一个文件和一个RandomAccessFile，用RandomAccessFile写入数据---------
			File fileC =new File("ccc.txt");
			RandomAccessFile raf=new RandomAccessFile(fileC,"rwd");			
			raf.seek(start);
			raf.write(str.getBytes(),0,str.length());
			raf.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}










结果：
创建了两个文件
bbb.txt  内容：ccc
ccc.txt  内容：aaabbbccc

运行结果
hello
aaa
bbb
ccc
aaa
bbb