技術標籤：學習總結設計模式java

單例模式

未完待續

//懶漢式執行緒不安全
public class Singleton {
    private static Singleton instance;
    private Singleton(){}
    public static Singleton getInstance(){
        if(instance==null){
            instance=new Singleton();
        }
        return instance;
    }
}
//懶漢式執行緒安全
class Singleton01
 
{
    private static Singleton01 instance;
    private Singleton01(){}
    public static synchronized Singleton01 getInstance(){
        if(instance==null){
            instance=new Singleton01();
        }
        return instance;
    }
}
/**
 * 餓漢式
 * 容易產生垃圾物件
 */
class Singleton02{
    private static Singleton02 instance=
 
new Singleton02();
    private Singleton02(){}
    public static Singleton02 getInstance(){
        return instance;
    }
}
/**
 * 雙重校驗鎖
 */
class Singleton03{
    private volatile static Singleton03 singleton03;
    private Singleton03(){}
    public static Singleton03 getSingleton03(){
        if(singleton03==
 
null){
            synchronized (Singleton.class){
                if(singleton03==null){
                    singleton03=new Singleton03();
                }
            }
        }
        return singleton03;
    }
}