Java学习笔记 - 第008天

作者: 迷茫o | 来源:发表于2016-12-07 19:47 被阅读0次

nio
《Netty实战》读书笔记01——第一章
Java 学习笔记(13)——lambda 表达式
java io
文章目录
Java学习日记
Java NIO 学习笔记（三）----Selector
Java NIO 学习笔记（二）----聚集和分散，通道到通道
Java NIO 学习笔记（四）----文件通道和网络通道
Java NIO 学习笔记（五）----路径、文件和管道 Pat

每日要点

修改器和访问器

修改器 - 属性的setter方法

    public void setXxx(T t) {
        this.t = t;
    }

访问器 - 属性的getter方法

    public T getXxx() {
        return t;
    }

toString()

将对象转换成字符串输出

@Override
public String toString() {
    // TODO Auto-generated method stub
    return super.toString();
}

文档注释
用来描述自己定义的类、变量、方法等，例如:

/**
 * 平面上的点
 * @author Kygo
 * @since 0.1
 */

昨天作业修正

1.定义一个类描述手机品牌尺寸等打电话发短信等call send short message install application Appuninstall / remove update
手机类:

  public class MobilePhone {
    private String brand;
    private String owner;
    private double size;
    private double price;
    private boolean isSmart;
    private String[] installedApps;
    private int numberOfApps;
    
    public MobilePhone(String brand, double size, double price, boolean isSmart) {
        this.brand = brand;
        this.size = size;
        this.price = price;
        this.isSmart = isSmart;
        if (this.isSmart) {
            this.installedApps = new String[100];
        }
    }

    // 修改器 - 属性的setter方法
    public void setOwner(String owner) {
        this.owner = owner;
    }
    
    // 访问器 - 属性的getter方法
    public String getOwner() {
        return owner;
    }
    
    public void show() {
        System.out.println(owner + "的价值" + price + "元的" + size +
                "英寸的" + brand + "手机");
    }
    
    public void call(String tel) {
        System.out.println("正在呼叫" + tel + "...");
    }
    
    public void sendShortMessage(String[] tels, String content) {
        for (String tel : tels) {
            System.out.println("向" + tel + "发送信息: " + content);
        }
    }
    
    public void installApp(String appName) {
        if (isSmart && numberOfApps < installedApps.length) {
            System.out.println("正在安装" + appName);
            installedApps[numberOfApps] = appName;
            numberOfApps += 1;
        }
        else {
            System.out.println("不能安装应用程序.");
        }
    }
    
    public void uninstallApp(String appName) {
        if (isSmart) {
            for (int i = 0; i < numberOfApps; i++) {
                if (installedApps[i].equals(appName)) {
                    System.out.println("正在卸载" + appName);
                    for (int j = i; j < numberOfApps - 1; j++) {
                        installedApps[j] = installedApps[j + 1];
                    }
                    numberOfApps -= 1;
                    return;
                }
            }
            System.out.println("没有这个应用程序.");
        }
        else {
            System.out.println("不能卸载应用程序.");
        }
    }
    
    public void runApp(String appName) {
        for (int i = 0; i < numberOfApps; i++) {
            if (installedApps[i].equals(appName)) {
                System.out.println("启动" + appName);
                return ;
            }
        }
        System.out.println("没有对应应用程序");
    }
}

测试类:

        MobilePhone phone1 = new MobilePhone("iphone 5S", 4, 2000, true);
        phone1.setOwner("张三");
        System.out.println(phone1.getOwner());
        phone1.show();
        phone1.installApp("捕鱼达人");
        phone1.installApp("微信");
        phone1.runApp("微信");
        phone1.runApp("欢乐斗地主");
        phone1.call("110");
        phone1.sendShortMessage(new String[] {"13213213", "1231242"},"晚上约吗");
        
        MobilePhone phone2 = new MobilePhone("山寨", 3, 200, false);
        phone2.setOwner("王大锤");
        phone2.show();
        phone2.installApp("王室战争");

2.写个程序模拟奥特曼打小怪兽hp mp攻击行为攻击参数小怪兽奥特曼必杀技小怪兽反击
奥特曼类:

public class Ultraman {
    private String name;
    private int hp;
    private int mp;
    
    public Ultraman(String name, int hp, int mp) {
        this.name = name;
        this.setHp(hp);
        this.mp = mp;
    }
    
    public String info() {
        return String.format("%s奥特曼 - 生命值: %d, 魔法值: %d",
                name, getHp(), mp);
    }

    public void attack(Monster m) {
        int injury = (int) (Math.random() * 11 + 10);
        m.setHp(m.getHp() - injury);
    }
    
    public void hugeAttack(Monster m) {
        if (mp >= 40) {
            int injury = m.getHp() / 4 * 3 > 50 ? m.getHp() / 4 * 3 : 50;
            m.setHp(m.getHp() - injury);
            mp -= 40;
        }
    }
    
    public void magicalAttack(Monster[] mArray) {
        if (mp >= 15) {
            for (Monster m : mArray) {
                if (m.getHp() > 0) {
                    int injury = (int) (Math.random() * 11 + 5);
                    m.setHp(m.getHp() - injury);
                }
            }
            mp -= 15;
        }
    }

    public void resumeMp() {
        mp += 4;
    }
    
    public int getHp() {
        return hp;
    }

    public void setHp(int hp) {
        this.hp = hp > 0 ? hp : 0;
    }

    public int getMp() {
        return mp;
    }
}

小怪兽类:

public class Monster {
    private String name;
    private int hp;
    
    public Monster(String name, int hp) {
        this.name = name;
        this.setHp(hp);
    }

    public String info() {
        return String.format("%s小怪兽 - 生命值: %d", name, getHp());
    }
    
    public void attack(Ultraman u) {
        int injury = (int) (Math.random() * 6 + 5);
        u.setHp(u.getHp() - injury);
    }

    public int getHp() {
        return hp;
    }

    public void setHp(int hp) {
        this.hp = hp < 0 ? 0 : hp;
    }
}

测试类:

    public static Monster selectOne(Monster[] mArray) {
        Monster temp = null;
        do {
            int randomIndex = (int) (Math.random() * mArray.length);
            temp = mArray[randomIndex];
        } while (temp.getHp() == 0);
        return temp;
    }
    
    public static void showMonsterInfo(Monster[] mArray) {
        for (Monster monster : mArray) {
            System.out.println(monster.info()); 
        }
    }
    
    public static boolean isAllDead(Monster[] mArray) {
        for (Monster monster : mArray) {
            if (monster.getHp() > 0) {
                return false;
            }
        }
        return true;
    }
    
    public static void main(String[] args) {
        Ultraman u = new Ultraman("迪迦", 250, 150);
        System.out.println(u.info());
        Monster m1 = new Monster("哥斯拉", 100);
        Monster m2 = new Monster("暴龙", 120);
        Monster m3 = new Monster("金刚", 140);
        Monster m4 = new Monster("异形", 150);
        Monster[] mArray = {m1, m2, m3, m4};
        showMonsterInfo(mArray);
        int round = 1;
        do {
            System.out.println("======第" + round + "回合======");
            int random = (int) (Math.random() * 10 + 1);
            Monster m = selectOne(mArray);
            if (random <= 7) {
                useNormalAttack(u, m);
            }
            else if (random <= 9) {
                if (u.getMp() >= 15) {
                    System.out.println("奥特曼使用了魔法攻击.");
                    u.magicalAttack(mArray);
                    for (Monster monster : mArray) {
                        if (monster.getHp() > 0) {
                            monster.attack(u);
                        }
                    } 
                }
                else {
                    useNormalAttack(u, m);
                }
            }
            else {
                if (u.getMp() >= 40) {
                    System.out.println("奥特曼使用了究极必杀技.");
                    u.hugeAttack(m);
                    if (m.getHp() > 0) {
                        m.attack(u);
                    } 
                }
                else {
                    useNormalAttack(u, m);
                }
            }
            if (u.getHp() > 0) {
                u.resumeMp();
            }
            System.out.println(u.info());
            showMonsterInfo(mArray);
            round += 1;
        } while (u.getHp() > 0 && !isAllDead(mArray));
        if (u.getHp() > 0) {
            System.out.println("奥特曼胜利!");
        }
        else {
            System.out.println("小怪兽胜利!");
        }
    }

    public static void useNormalAttack(Ultraman u, Monster m) {
        System.out.println("奥特曼使用了普通攻击.");
        u.attack(m);
        if (m.getHp() > 0) {
            m.attack(u);
        }
    }

**3.改造成面向对象围墙过道 **
圆类:

public class Circle {

    private double radius;
    
    public Circle(double radius) {
        this.radius = radius;
    }

    public double perimeter() {
        return 2 * Math.PI * radius;
    }
    
    public double area() {
        return Math.PI * radius * radius;
    }
}

测试类:

    private static final double AISLE_UNIT_PRICE = 38.5;
    private static final double FENCE_UNIT_PRICE = 15.5;

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("请输入游泳池的半径: ");
        double r = input.nextDouble();
        Circle small = new Circle(r);
        Circle big = new Circle(r + 3);
        System.out.printf("围墙的造价为: ￥%.2f元\n",
                big.perimeter() * FENCE_UNIT_PRICE);
        System.out.printf("过道的造价为: ￥%.2f元\n",
                (big.area() - small.area()) * AISLE_UNIT_PRICE);
        input.close();
    }

练习

1.定义一个类描述矩形

public class Rectangle {
    private double height;
    private double width;
    
    public Rectangle(double height, double width) {
        this.height = height;
        this.width = width;
    }

    public double perimeter() {
        return 2 * (height + width);
    }
    
    public double area() {
        return height * width;
    }

    public double getHeight() {
        return height;
    }

    public void setHeight(double height) {
        this.height = height;
    }

    public double getWidth() {
        return width;
    }

    public void setWidth(double width) {
        this.width = width;
    }
}

例题

1.定义一个类描述平面点可以移动修改点能计算这个点到另外一个点的距离
点类:

/**
 * 平面上的点
 * @author Kygo
 * @since 0.1
 */
// 定义一个类描述平面  点 可以移动修改点 能计算这个点到另外一个点的距离
public class Point {
    private double x;  // 横坐标
    private double y;  // 纵坐标
    
    /**
     * 构造器
     * @param x 横坐标
     * @param y 纵坐标
     */
    public Point(double x, double y) {
        this.x = x;
        this.y = y;
        // this.moveTo(x, y);
    }
    
    /**
     * 移动到
     * @param newX 新的横坐标
     * @param newY 新的纵坐标
     */
    // 移动到
    public void moveTo(double newX, double newY) {
        x = newX;
        y = newY;
    }
    
    /**
     * 移动了
     * @param dx 横坐标的增量
     * @param dy 纵坐标的增量
     */
    // 移动了
    public void moveBy(double dx, double dy) {
        x += dx;
        y += dy;
    }
    
    /**
     * 计算到另一个点的距离
     * @param other 另一个点
     * @return 两个点的距离
     */
    public double distanceTo(Point other) {
        // this到other的距离
        double dx = this.x - other.x;
        double dy = this.y - other.y;
        return Math.sqrt(dx * dx + dy * dy);
    }
    
    // 将对象转换成字符串输出
    @Override
    public String toString() {
        return "(" + x + "," + y + ")";
    }
}

2.定义一条线段

// 文档注释
/**
 * 平面上的线条
 * @author Kygo
 * @since 0.2
 */
//定义一条线段
public class Line {
    private Point start;
    private Point end;
    
    /**
     * 构造器
     * @param start 线段的起点
     * @param end 线段的终点
     */
    public Line(Point start, Point end) {
        this.start = start;
        this.end = end;
    }

    /**
     * 获取线段的长度
     * @return 线段的长度
     */
    public double length() {
        return start.distanceTo(end);
    }   
}

作业

1.写一个类描述数学上的分数提供分数的加减乘除的运算化简
分数类:

public class Fraction {
    private int numerator;  // 分子
    private int denominator;  // 分母
    
    public Fraction(int numerator, int denominator) {
        this.numerator = numerator;
        this.denominator = denominator;
    }

    public Fraction add(Fraction f) {
        Fraction result = new Fraction(0, 0);
        result.numerator = (this.numerator * f.denominator) + 
                (f.numerator * this.denominator);
        result.denominator = this.denominator * f.denominator;
        result.reduction();
        return result; 
    }
    
    public Fraction subtract(Fraction f) {
        Fraction result = new Fraction(0, 0);
        result.numerator = (this.numerator * f.denominator) - 
                (f.numerator * this.denominator);
        result.denominator = this.denominator * f.denominator;
        result.reduction();
        return result;
    }
    
    public Fraction multiply(Fraction f) {
        Fraction result = new Fraction(0, 0);
        result.denominator = this.denominator * f.denominator;
        result.numerator = this.numerator * f.numerator;
        result.reduction();
        return result;
    }
    
    public Fraction divide(Fraction f) {
        Fraction result = new Fraction(0, 0);
        result.denominator = this.denominator * f.numerator;
        result.numerator = this.numerator * f.denominator;
        result.reduction();
        return result;
    }
    
    public void reduction() {
        int min = denominator > Math.abs(numerator) ? Math.abs(numerator) : denominator;
        for (int i = min; i >= 2; i--) {
            if (numerator % i == 0 && denominator % i == 0) {
                numerator /= i;
                denominator /= i;
                return ;
            }
        }
    }
    
    @Override
    public String toString() {
        if (numerator != 0) {
            return numerator + "/" + denominator;
        }
        else {
            return "0";
        }
    }
}

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