Posted on 2006-11-26 13:57
Jaunt 閱讀(761)
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咖啡Java
原文出處:
http://www.javatang.com/archives/2006/06/27/512049.html
編輯: Jaunt
聲明: 請維持文章的完整性任意轉載
SingletonTest.java：
public class SingletonTest {
??? public static void main(String[] args) {
??????? Singleton s1 = Singleton.getInstance();
??????? Singleton s2 = Singleton.getInstance();
??????? System.out.println("s1=s2?" + (s1==s2));
??????? System.out.println("s1.getNextID = " + s1.getNextID());
??????? System.out.println("s2.getNextID = " + s2.getNextID());
??????? System.out.println("s1.getNextID = " + s1.getNextID());
??????? System.out.println("s1.getNextID = " + s1.getNextID());
??????? System.out.println("s2.getNextID = " + s2.getNextID());
??????? System.out.println("s2.getNextID = " + s2.getNextID());
??? }
}
class Singleton {
??? private static int nextID = 0;
??? private static Singleton instance = null;
??? private Singleton() {};
??? public static synchronized Singleton getInstance() {
??????? if (instance == null) {
??????????? instance = new Singleton();
??????? }
??????? return instance;
??? }
??? // inside data
??? public synchronized int getNextID() {
??????? return ++nextID;
??? }
}
輸出結果：
s1=s2?true
s1.getNextID = 1
s2.getNextID = 2
s1.getNextID = 3
s1.getNextID = 4
s2.getNextID = 5
s2.getNextID = 6