Java单例设计、多例设计、枚举

水深无声 2023-01-07 07:08 166阅读 0赞

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package com.msc.example;
    //饿汉式
    class Sinleton{ 
        private static final Sinleton INSTANCE = new Sinleton() ;
        private Sinleton () { } ;
        public static Sinleton getInstance(){ 
            return INSTANCE ;
        }
        public void print(){ 
            System.out.println("单例设计模式饿汉式");
        }
    }
    //懒汉式
    class SinletonB{ 
        private static  SinletonB instance ;
        private SinletonB () { } ;
        public static SinletonB getInstance(){ 
            if(instance == null){ 
                instance = new SinletonB() ;
            }
            return instance ;
        }
        public void print(){ 
            System.out.println("单例设计模式懒汉式");
        }
    }
    //多例设计模式
    class Color{ 
        private static final Color RED = new Color("红色") ;
        private static final Color GREEN = new Color("绿色") ;
        private static final Color BLUE = new Color("蓝色") ;
        public String color ;
        private Color(String color){ 
            this.color = color ;
        }
        public static Color getColor(String color){ 
            switch (color){ 
                case "red" : return RED ;
                case "green" : return GREEN ;
                case "blue" : return BLUE ;
                default: return null ;
            }
        }
        public String toString(){ 
            return this.color ;
        }
    }
    //枚举 多例设计模式
    interface IMessage{ 
        public void print() ;
    }
    enum ColorB implements IMessage{ 
        RED("红色"){ 
            @Override
            public String getMessage() { 
                return this.toString();
            }
        } , BLUE("蓝色"){ 
            @Override
            public String getMessage() { 
                return this.toString();
            }
        } , GREEN("绿色"){ 
            @Override
            public String getMessage() { 
                return this.toString();
            }
        };
        private String color ;
        private ColorB() { } ;
        private  ColorB(String color){ 
            this.color = color ;
        }
    
        @Override
        public String toString() { 
            return "ColorB{" +
                    "color='" + color + '\'' +
                    '}';
        }
    
        public void print(){ 
            System.out.println("枚举实现接口");
        }
        public abstract String getMessage() ;
    
    }
    enum Sex{ 
        MALE("男"),FEMALE("女") ;
        private String sex ;
        private Sex () { } ;
        private Sex (String sex){ 
            this.sex = sex ;
        }
    
        @Override
        public String toString() { 
            return this.sex ;
        }
    }
    class PersonD{ 
        private String name ;
        private Sex sex ;
        public PersonD () { } ;
        public PersonD (String name,Sex sex) { 
            this.name = name ;
            this.sex = sex ;
        } ;
    
        @Override
        public String toString() { 
            return "PersonD{" +
                    "name='" + name + '\'' +
                    ", sex=" + sex +
                    '}';
        }
    }
    public class SingletonDemo { 
        public static void main(String[] args) { 
            System.out.println("----------单例-------------");
            Sinleton instance = null ;
            instance = Sinleton.getInstance() ;
            instance.print();
            SinletonB instancec = null ;
            instancec = SinletonB.getInstance() ;
            instancec.print();
            System.out.println("----------多例-------------");
            Color red = Color.getColor("red");
            System.out.println(red.toString());
            Color blue = Color.getColor("blue");
            System.out.println(blue.toString());
            System.out.println("----------枚举-------------");
            IMessage msg = ColorB.RED ;
            msg.print();
            for(ColorB c : ColorB.values()){ 
                System.out.println(c.toString());
            }
            ColorB c = ColorB.GREEN ;
            System.out.println("----------枚举switch-------------");
            switch (c){ 
                case RED -> System.out.println(ColorB.RED.getMessage()) ;
                case GREEN -> System.out.println(ColorB.GREEN.getMessage()) ;
                case BLUE -> System.out.println(ColorB.BLUE.getMessage()) ;
                default -> System.out.println("默认") ;
            }
            System.out.println("----------枚举option-------------");
            System.out.println(new PersonD("张三",Sex.MALE));
        }
    }

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