关于文件输入时出现FileNotFoundException的问题

Question

一个实现文件拷贝的程序：
源程序如下：
import java.io.*;
class Txtcopy
{    public static void main(String[] args)
     {  byte[] b1=new byte[255];
        byte[] b2=new byte[255];
        byte[] b3=new byte[2056];
        byte[] b4=new byte[2056];
        try
          {  System.out.println("请输入源文件名称：\n");
             System.in.read(b1,0,255);
             System.out.println("\n请输入目的文件名称：\n");
             System.in.read(b2,0,255);
             String sourceName=new String(b1,0);
             String desName=new String(b2,0);
             FileInputStream fileInput=new FileInputStream(sourceName);
             int bytes1=fileInput.read(b3,0,2056);
             String sourceFile=new String(b3,0,0,bytes1);
             FileOutputStream fileOutput=new FileOutputStream(desName);
             fileOutput.write(b3,0,bytes1);
             fileInput=new FileInputStream(desName);
             int bytes2=fileInput.read(b4,0,2056);
             String desFile=new String(b4,0,0,bytes2);
             System.out.println("\n源文件内容为：");
             System.out.println(sourceFile);
             System.out.println("\n目的文件内容为：");
             System.out.println(desFile);          }
          catch(Exception e)
          {  System.out.println(e.toString());  }
     }
}
在输入源文件名称时总是提示FileNotFoundException,但文件确实存在。请教原因！

Answer 1

import java.io.*;
class Txtcopy
{    public static void main(String[] args)
     {  byte[] b1=new byte[255];
        byte[] b2=new byte[255];
        byte[] b3=new byte[2056];
        byte[] b4=new byte[2056];
        try
          {  System.out.println("请输入源文件名称：\n");
             System.in.read(b1,0,255);
             System.out.println("\n请输入目的文件名称：\n");
             System.in.read(b2,0,255);
             String sourceName=new String(b1,0);
             String desName=new String(b2,0);
             FileInputStream fileInput=new FileInputStream("Txtcopy.java");
             int bytes1=fileInput.read(b3,0,2056);
             String sourceFile=new String(b3,0,0,bytes1);
             File f1 = new File(sourceFile);
             FileOutputStream fileOutput=new FileOutputStream(f1);
             fileOutput.write(b3,0,bytes1);
             File f2 = new File(desName);
             fileInput=new FileInputStream(f2);
             int bytes2=fileInput.read(b4,0,2056);
             String desFile=new String(b4,0,0,bytes2);
             System.out.println("\n源文件内容为：");
             System.out.println(sourceFile);
             System.out.println("\n目的文件内容为：");
             System.out.println(desFile);          }
          catch(Exception e)
          {  System.out.println(e.toString());  }
     }
}

Answer 2

平台问题,不同的平台的目录表示形式不一样,java 不能自动识别是哪个平台的目录,所以就出现了FileNotFoundException