Java示范设计模式中的单件模式

Java演示设计模式中的单件模式，单件模式是我们经常用到的，防止用户同时创建多个类实例

public class SimpleSingleton {
    private static SimpleSingleton singleInstance =  new SimpleSingleton();
 
    //Marking default constructor private
    //to avoid direct instantiation.
    private SimpleSingleton() {
    }
 
    //Get instance for class SimpleSingleton
    public static SimpleSingleton getInstance() {
 
        return singleInstance;
    }
}

调用方法

public enum SimpleSingleton {
    INSTANCE;
    public void doSomething() {
    }
}
 
//Call the method from Singleton:
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SimpleSingleton.INSTANCE.doSomething();