Design Patterns Common Interview Questions

1. Write a singleton class.

// The first form: hungry Chinese singleton
public class Singleton {  
    private Singleton(){}  
    private static Singleton instance = new Singleton();  
    public static Singleton getInstance(){  
        return instance;  
    }  
}  

// The second form: lazy singleton
public class Singleton {  
    private static Singleton instance = null;  
    private Singleton() {}  
    public static synchronized Singleton getInstance(){  
        if (instance==null) instance＝newSingleton();  
        return instance;  
    }  
}  

 

2. Tell us about the design patterns you are familiar with or heard of and what design patterns have you used in your development? 

    Creation type: simple factory, factory method, abstract project, builder mode, singleton, prototype(clone)

    Structural Types: Adapter, Decorator, Bridge, Facade, Composition, Proxy Mode

    Behavioral: command pattern, observer, strategy pattern, template, state pattern, iterator pattern, memo pattern