必需int，但存在问题，发现零字节。

    File f=new File(\"d:/tester.txt\");
    long size=f.length();  // returns the size in bytes
    char buff[]=new char[size]; // line of ERROR
                // will not accept long in it\'s argument
                // I can\'t do the casting (loss of data)

size

buff

import java.io.*;
class tester {
 public static void main(String args[]) {
 File f=new File(\"c:/windows/system32/drivers/etc/hosts.File\");
 long x=f.length();  // returns the number of bytes read from the file
 System.out.println(\"long-> \" + x );
}

long-> 0

char buff[]=new char[(int) size];

byte[] buff=new byte[(int) size];

f.exists()