randomaccessexp.java

Java课堂练习

/**
 * @(#)RandomAccessExp.java
 *
 *
 * @author 
 * @version 1.00 2007/11/17
 */
import java.io.*;


public class RandomAccessExp {
        
    /**
     * Creates a new instance of <code>RandomAccessExp</code>.
     */
    public RandomAccessExp() {
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        try {
        RandomAccessFile  raf=new RandomAccessFile(args[0],"rw");
        int wrtcnt=Integer.valueOf(args[1]).intValue();
        int wrtpos=Integer.valueOf(args[2]).intValue();
        int readcnt=Integer.valueOf(args[3]).intValue();
        int readpos=Integer.valueOf(args[4]).intValue();
        raf.seek(wrtpos);
        char c;
        for (int i=1; i<=wrtcnt; i++) {
         c=(char)('a'+i);
         System.out.print(c);
         raf.writeChar(c);         
        }
        System.out.println("");
        raf.seek(readpos);
        for (int i=1; i<=readcnt; i++) {
        try {
         c=raf.readChar();
         System.out.print(c);
        }
        catch (EOFException eofe) {
         break;
        }
        }
     }
     catch (Exception e) {
      e.printStackTrace();
     }
        
          
        
   }
 }