静态字段与静态方法_练习

对象村出生人数

public class Person {
    private final String name; // 姓名
    private final int height; // 身高

    private static int numberOfPeople = 0; // 人数

    public Person(String name, int height) {
        this.name = name;
        this.height = height;
        numberOfPeople++; // !!!由于设置为private,本代码下只能通过构造器修改numberOfPeople字段
    }

    // getNumberOfPeople通过Generate...生成
    public static int getNumberOfPeople() { // 这是一个静态方法
        return numberOfPeople;
    }

    public static void main(String[] args) {
        // 方便起见,直接在Person类中添加一个main方法测试Person类
        // 而不再引入PersonTest类
        System.out.printf("对象村已出生 %d 人%n", Person.getNumberOfPeople());
        // 无需创建对象,也可以直接使用静态方法访问静态变量! 静态的东西先于对象存在!
        Person p = new Person("张三", 175);
        Person p2 = new Person("李四", 185);
        System.out.printf("对象村已出生 %d 人%n", Person.getNumberOfPeople());

        for (int i = 0; i != 20; ++i) {
            new Person("王五", 180);
        }
        System.out.printf("对象村已出生 %d 人%n", Person.getNumberOfPeople());
    }
}

自动回合对战改进版

Hero.java

public class Hero {
    private static final int MIN_HP = 0;
    private static final int MAX_HP = 100; // 限制小兵的最大生命值
    private static final int MAX_MAX_DAMAGE = 50; // 限制小兵的最大伤害值

    private static int randomCharacterId = 0; // 保存角色id
    public static boolean isDebugMode = true; // 控制是否打印对战细节,不开启则只打印对战结果

    private final String heroName; // 英雄名称
    private int hp; // 血条、生命值
    private final int maxDamage; // 表示角色能够造成的最大伤害值

    private Hero(String heroName, int hp, int maxDamage) {
        // 请注意,这里将构造器设置为private使得无法在其它类中调用Hero构造器创建对象
        this.heroName = heroName;
        this.hp = hp;
        this.maxDamage = maxDamage;
    }

    public static Hero of(String heroName, int hp, int maxDamage) {
        return new Hero(heroName, hp, maxDamage);
    }

    public static Hero randomCharacter() {
        String name = "小兵#" + randomCharacterId; // 小兵名字
        randomCharacterId++; // id需要保持唯一,自增1
        int hp = 10 + (int)(Math.random() * MAX_HP); // 小兵hp在10~110
        int maxDamage = 10 + (int)(Math.random() * MAX_MAX_DAMAGE); // 小兵攻击在10~60

        return new Hero(name, hp, maxDamage);
    }

    public String getHeroName() {
        return heroName;
    }

    public int getHp() {
        return hp;
    }

    public void attack(Hero otherHero) {
        int damage = (int)(Math.random() * maxDamage); // 生成伤害值,随机造成0~maxDamage的伤害
        // 对应英雄承受该伤害
        otherHero.takeDamage(damage);
        if (isDebugMode) {
            System.out.printf("%s 对 %s 造成了 %d 点伤害", this.heroName, otherHero.heroName, damage);
            System.out.printf("（%s 还剩 %d 生命值）\n", otherHero.heroName, otherHero.getHp());
        }
    }

    public void takeDamage(int damage) {
        this.hp -= damage;
        if (this.hp < MIN_HP) {
            this.hp = MIN_HP;
        }
    }

    public boolean isAlive() {
        return this.hp > MIN_HP;
    }

    public static void battle(Hero hero1, Hero hero2) {
        System.out.printf("%s(HP: %d) 与 %s(HP: %d) 开始对战\n", hero1.getHeroName(), hero1.getHp(), hero2.getHeroName(), hero2.getHp());

        int round = 1;
        while (hero1.isAlive() && hero2.isAlive()) {
            if (isDebugMode) {
                System.out.printf("********* 回合 %d *********\n", round);
            }
            round++;
            hero1.attack(hero2);
            hero2.attack(hero1);
        }

        System.out.printf("经过 %d 回合对战 ", round - 1);
        if (hero1.isAlive()) {
            System.out.printf("%s 胜出%n", hero1.getHeroName());
        } else if (hero2.isAlive()) {
            System.out.printf("%s 胜出%n", hero2.getHeroName());
        } else {
            System.out.printf("%s 与 %s 同归于尽%n", hero1.getHeroName(), hero2.getHeroName());
        }
        System.out.println();
    }
}

 HeroTest.java

public class HeroTest {
    public static void main(String[] args) {
        Hero hero1 = Hero.of("齐天大圣", 250, 105);
        Hero hero2 = Hero.of("二郎神", 110, 45);

        Hero.battle(hero1, hero2);

        Hero.isDebugMode = false;

        for (int i = 0; i != 10; ++i) {
            if (hero1.isAlive()) {
                Hero.battle(hero1, Hero.randomCharacter());
            }
        }
    }
}