randomlist.java

《Java案例开发》源代码( 考勤系统的完整实现！） 包括数据库 网络通讯＆uml

/*
 * RandomList.java
 *
 * Created on 2003年11月28日, 下午4:02
 */

package romulus;

import java.util.*;

/**
 *
 * @author  Administrator
 * @version 
 */
public class RandomList extends java.util.AbstractList implements java.io.Serializable{

    private java.util.Vector backVector;
    
    /** Creates new RandomList */
    public RandomList() {
        backVector = new Vector();
    }
    
    public RandomList(Collection c){
        Vector oldv = new Vector(c);
        backVector = new Vector();
        Object obj = null;
        Random rand = new Random();
        for(int ranint, i = oldv.size(); i>0; i--){
            ranint = Math.abs(rand.nextInt()) % i;
            obj = oldv.remove(ranint);
            backVector.add(obj);
        }
    }

    public java.lang.Object get(int param) {
        return backVector.get(param);
    }
    
    public java.lang.Object set(int param, java.lang.Object obj) {
        return backVector.set(param, obj);
    }
    
    public java.lang.Object remove(int param) {
        return backVector.remove(param);
    }
    
    public void add(int param, java.lang.Object obj) {
        Random rand = new Random();
        int ranint = 0;
        if(backVector.size()!=0){
            ranint = Math.abs(rand.nextInt()) % backVector.size();
        }
        backVector.add(ranint, obj);
    }
    
    public int size() {
        return backVector.size();
    }
    
    public Vector toVector(){
        return backVector;
    }
    
    public static void main(String args[]){
        Vector t = new Vector();
        t.add("Car");
        t.add("Bar");
        t.add("Aar");
        t.add("Xar");
        RandomList randl = new RandomList(t);
        for(Iterator i = randl.iterator(); i.hasNext(); ){
            System.out.println(i.next()+"");
        }
    }
    
}