java基础总结 --- enum枚举的常量相关方法、自动售货机(状态模式)例子

package com.zghw.base.enumx;import java.text.DateFormat;import java.util.Date;/** * 允许程序员为enum实例编写方法，从而为每个enum实例赋予各自不同的行为。 * 要实现常量相关的方法，你需要为enum定义一个或多个abstract方法， * 然后为每个enum实例实现该抽象方法 * @author zghw * */public enum ConstantSpecificMethod {  DATE_TIME{  String getInfo(){  return DateFormat.getInstance().format(new Date());  }  },  CLASSPATH{  String getInfo(){  return System.getenv("CLASSPATH");  }  },  VERSION{  //实现抽象接口方法  String getInfo(){  return System.getProperty("java.version");  }  //重写方法  void print(){  System.out.println("重写了"+this);  }  };  abstract String getInfo();  void print(){  System.out.println(this);  }  public static void main(String args[]){  for(ConstantSpecificMethod c: ConstantSpecificMethod.values()){  c.print();  System.out.println(c.getInfo());  }  }  /**   * 在面向对象设计中，不同的行为与不同的类关联。而通过常量相关的方法，   * 每个enum实例可以具备自己独特的行为，说明每个enum实例就像一个独特的类。   * 在调用getInfo()方法时，体现了多态。   */}

package com.zghw.base.enumx;import java.util.EnumSet;/** * 洗车服务菜单实例 *  * @author zghw * */public class CarWash {public enum Cycle {UNDERBODY {void action() {System.out.println(this);}},WHEELWASH {void action() {System.out.println(this);}},PERWASH {void action() {System.out.println(this);}},BASIC {void action() {System.out.println(this);}},HOTWAX {void action() {System.out.println(this);}},RINSE {void action() {System.out.println(this);}},BLOWDRY {void action() {System.out.println(this);}};abstract void action();}EnumSet<Cycle> cs = EnumSet.of(Cycle.BASIC, Cycle.RINSE);public void add(Cycle cw) {cs.add(cw);}public void washCar() {for (Cycle c : cs) {c.action();}}public String toString() {return cs.toString();}public static void main(String[] args) {CarWash cc = new CarWash();System.out.println(cc);cc.add(Cycle.BLOWDRY);System.out.println(cc);cc.add(Cycle.PERWASH);cc.add(Cycle.WHEELWASH);cc.add(Cycle.BASIC);cc.add(Cycle.BLOWDRY);System.out.println(cc);// 向EnumSet中添加的顺序并不重要，因为输出的次序决定于enum实例定义时的次序cc.washCar();}}

下面是自动售货机的例子，全面的使用枚举特性：

package com.zghw.base.enumx;import java.util.Random;/** * 售卖机所有输入 *  * @author zghw * */public enum Input {NICKE(15),DIME(10),QUARTER(25),DOLLAR(100),TOOTHPASTE(200),CHIPS(75),SODA(100),SOAP(50),ABORT_TRANSACTION {// 重写getValue()方法public int getValue() {throw new RuntimeException("transaction no value");}},STOP {public int getValue() {throw new RuntimeException("had stop no value");}};// 输入对应的价格值private int value;private Input(int value) {this.value = value;}// 枚举对应的多个构造函数private Input() {}// 取得对应的价格public int getValue() {return value;}static Random random = new Random(47);// 随机选择一个输入,由于STOP不是一个输入，所以随机值减少STOPpublic static Input randomSelect() {return values()[random.nextInt(values().length - 1)];}}

package com.zghw.base.enumx;import static com.zghw.base.enumx.Input.*;import java.util.EnumMap;/** * 输入进行分类 * @author zghw * */public enum Category {MONEY(NICKE,DIME,QUARTER,DOLLAR),ITEM_SELECTION(TOOTHPASTE, CHIPS,SODA,SOAP),QUIT_TRANSACTION(ABORT_TRANSACTION),    SHUT_DOWN(STOP);private Input[] categories;private Category(){}private Category(Input... categories){this.categories = categories;}//获取分类对象表public static EnumMap<Input,Category> getCategoryMap(){EnumMap<Input,Category> categoryMap=new EnumMap<Input,Category>(Input.class);for(Category c: Category.values()){for(Input i:c.categories){categoryMap.put(i, c);}}return categoryMap;}//根据输入获取分类public static Category get(Input input){return getCategoryMap().get(input);}}

package com.zghw.base.enumx;import static com.zghw.base.enumx.VendingMachine.StateDuration.TRANSIENT;import java.util.Arrays;import java.util.Iterator;/** * 自动售货机 责任链和状态模式 *  * @author zghw * */public class VendingMachine {// 当前自动售货机处理的状态private static State state = State.RESTRING;// 当前输入private static Input selection = null;// 花费钱统计private static int amount = 0;enum StateDuration {// 持续状态 1.瞬时TRANSIENT};enum State {// 五种状态 1.重置2.付款3.系统配置4.取消5.终端RESTRING {public void next(Input input) {switch (Category.get(input)) {case MONEY:amount += input.getValue();state = ADDING_MONEY;break;case SHUT_DOWN:state = TERMINAL;break;default:break;}}},ADDING_MONEY {public void next(Input input) {switch (Category.get(input)) {case MONEY:amount += input.getValue();break;case ITEM_SELECTION:selection = input;if (amount < selection.getValue()) {System.out.println("不够支付" + selection);} else {state = DISPENSING;}break;case QUIT_TRANSACTION:state = GIVING_CHANGE;break;case SHUT_DOWN:state = TERMINAL;break;default:break;}}},DISPENSING(TRANSIENT) {public void next() {System.out.println("你选择的是：" + selection);amount -= selection.getValue();state = GIVING_CHANGE;}},GIVING_CHANGE(TRANSIENT) {public void next() {if (amount > 0) {System.out.println("变成" + amount);amount = 0;}state = RESTRING;}},TERMINAL {void output() {System.out.println("终止");}};// 售货机在处理中private boolean isTransient = false;// 使用构造函数巧妙的设置了状态是瞬时的还是持续的private State() {}private State(StateDuration sd) {isTransient = true;}// 进入下一个状态public void next() {throw new RuntimeException("不用实现");}// 进入输入对应的下一个状态public void next(Input input) {throw new RuntimeException("不用实现");}void output() {System.out.println(amount);}}// 运行public static void run(Generator<Input> gi) {// 没有显示终端则继续运行while (state != State.TERMINAL) {state.next(gi.next());// 瞬时状态继续运行while (state.isTransient) {// 进入下一个状态state.next();}state.output();}}public static void main(String args[]) {Generator<Input> gi = new RandomInputGenerator();String fileName = "QUARTER;QUARTER;QUARTER;CHIPS;DOLLAR;DOLLAR;TOOTHPASTE;QUARTER;DIME;ABORT_TRANSACTION;QUARTER;DIME;SODA;QUARTER;DIME;NICKE;SODA;ABORT_TRANSACTION;STOP";gi = new FileInputGenerator(fileName);run(gi);}}class RandomInputGenerator implements Generator<Input> {@Overridepublic Input next() {return Input.randomSelect();}}class FileInputGenerator implements Generator<Input> {//迭代器适合下一个private Iterator<String> input;public FileInputGenerator(String fileName) {//数组转换为集合 集合转换为迭代器input = Arrays.asList(fileName.split(";")).iterator();}@Overridepublic Input next() {if (input.hasNext()) {return Enum.valueOf(Input.class, input.next());}return null;}}