io-stream UsingRandomAccessFile

package stream.demo1;

import java.io.IOException;
import java.io.RandomAccessFile;

/** 文件操作类，游离于IO树形结构外，类似DataInputStream和DataOutputStream 的集成类 */
public class UsingRandomAccessFile
{
    static String file = "rtest.dat";
    
    static void display()
        throws IOException
    {
        RandomAccessFile rf = new RandomAccessFile(file, "r");
        for (int i = 0; i < 7; i++)
            System.out.println("Value " + i + " : " + rf.readDouble());
        System.out.println(rf.readUTF());
        rf.close();
    }
    
    public static void main(String[] args)
        throws IOException
    {
        // RandomAccessFile适用于由大小已知的记录组成的文件，可以用seek()将记录从一处转移到另一处
        RandomAccessFile rf = new RandomAccessFile(file, "rw");
        for (int i = 0; i < 7; i++)
            rf.writeDouble(i * 1.414);
        rf.writeUTF("the end of the file");
        rf.close();
        display();
        rf = new RandomAccessFile(file, "rw");
        rf.seek(5 * 8);// 偏移40个直接，不包含空格
        rf.writeDouble(47.0001);
        rf.close();
        display();
    }
    
}