设计模式

单例模式

饿汉式

 

 

 

 

 

 

public class Hunger {
    public static void main(String[] args) {
        ExampleHunger instance = ExampleHunger.getInstance();
        System.out.println(instance);
    }
}

class ExampleHunger{
    private String name;
    private static ExampleHunger example = new ExampleHunger("张三");

    private ExampleHunger(String name) {
        this.name = name;
    }

    public static ExampleHunger getInstance(){
        return example;
    }

    @Override
    public String toString() {
        return "Example{" +
                "name='" + name + '\'' +
                '}';
    }
}

懒汉式

 

 

 

public class Lazy {
    public static void main(String[] args) {
        ExampleLazy instance = ExampleLazy.getInstance();
        System.out.println(instance);
    }
}

class ExampleLazy{
    private String name;
    private static ExampleLazy example;

    private ExampleLazy(String name) {
        this.name = name;
    }

    public static ExampleLazy getInstance(){
        if (example == null){
            example = new ExampleLazy("张三");
        }
        return example;
    }

    @Override
    public String toString() {
        return "ExampleLazy{" +
                "name='" + name + '\'' +
                '}';
    }
}

 模板模式