listofnumbers2.java

北大Java 语言程序设计 ppt课件及源码

import java.io.*;
import java.util.Vector;

public class ListOfNumbers2 {
    private Vector victor;
    private static final int size = 10;

    public ListOfNumbers2() {
        victor = new Vector(size);
        for (int i = 0; i < size; i++)
            victor.addElement(new Integer(i));

	this.readList("infile.txt");
	this.writeList();
    }

    public void readList(String fileName) {
	String line = null;
	try {
	    RandomAccessFile raf = new RandomAccessFile(fileName, "r");
	    while ((line = raf.readLine()) != null) {
		Integer i = new Integer(Integer.parseInt(line));
		System.out.println(i);
		victor.addElement(i);
	    }
	} catch(FileNotFoundException fnf) {
	    System.err.println("File: " + fileName + " not found.");
	} catch (IOException io) {
	    System.err.println(io.toString());
	}
    }

    public void writeList() {
        PrintWriter out = null;

        try {
            out = new PrintWriter(new FileWriter("outfile.txt"));
        
            for (int i = 0; i < victor.size(); i++)
                out.println("Value at: " + i + " = " + victor.elementAt(i));
        } catch (ArrayIndexOutOfBoundsException e) {
            System.err.println("Caught ArrayIndexOutOfBoundsException: " +
				 e.getMessage());
        } catch (IOException e) {
            System.err.println("Caught IOException: " + e.getMessage());
        } finally {
            if (out != null) {
                System.out.println("Closing PrintWriter");
                out.close();
            } else {
                System.out.println("PrintWriter not open");
            }
        }
    }

    public static void main(String[] args) {
	new ListOfNumbers2();
    }
}