observerb.java

来自「java的23中设计模式的代码实现」· Java 代码 · 共 33 行

/**
 *  A concrete observer
 *  This observer, can not change subject, 
 *  but it can print the content in vector sorted by alphameric
 */
import java.io.*;
import java.util.*;

public class ObserverB implements Observer {
    private Vector strVector;
    public ObserverB() {
        strVector =  new Vector();
    }
    public void update(Subject subject) {
        strVector = (Vector)(subject.getState()).clone();
        //-----  Sorted vector  ---------------------------
        for (int i = strVector.size(); --i >= 0; ) {
            for (int j = 0; j < i; j++) {
                String str1 = (String)strVector.get(j);
                String str2 = (String)strVector.get(j+1);
                if((str1.compareTo(str2)) > 0) {
                    strVector.setElementAt(str2, j);
                    strVector.setElementAt(str1, j+1);
                }
            }
        }
        System.out.println("----- ObserverB will be updated -----");
        for(int i = 0; i < strVector.size(); i++) {
            System.out.println("Num " + i + " is :" + (String)strVector.get(i));
        }
    }
    
}