iodemo7.java

Java讲义与实例

import java.io.*;
public class IODemo7{
    public static void main(String arg[]){
       String s=new String();
       float f=3.145f;
       try{
        RandomAccessFile rwFile1=new RandomAccessFile(
                                "d:\\javacode\\rwtest.dat","rw");
        rwFile1.writeFloat(3.14f);
        rwFile1.writeFloat(4.14f);
        rwFile1.writeFloat(5.14f);
        rwFile1.writeFloat(10.14f);
        rwFile1.writeFloat(9.14f);
        rwFile1.close();
        RandomAccessFile rFile1=new RandomAccessFile(
                       "d:\\javacode\\rwtest.dat","r");
        System.out.println("the first time when written");
        for (int i=0;i<5;i++)
            System.out.println("Value"+i+":"+rFile1.readFloat());
        rFile1.close();
        RandomAccessFile rwFile2=new RandomAccessFile(
                                "d:\\javacode\\rwtest.dat","rw");        
        rwFile2.seek(8);
        System.out.println("pos1="+rwFile2.getFilePointer());
        rwFile2.writeFloat(0f);
        System.out.println("pos2="+rwFile2.getFilePointer());
        rwFile2.close();
        RandomAccessFile rFile2=new RandomAccessFile(
                       "d:\\javacode\\rwtest.dat","r");
        System.out.println("the second time when written");
        for (int i=0;i<5;i++)
             System.out.println("Value"+i+":"+rFile2.readFloat());
        System.out.println("pos3="+rFile2.getFilePointer());
        System.out.println("length="+rFile2.length());
        rFile2.close();
        
        }catch (Exception e){}
        }
        
    }