java 定义一个可直接取值的常量类

1、定义一个交通工具的类Vehicle：创建对象，get/set，if(), 构造方法，this.

/*请定义一个交通工具的类Vehicle
* 其中有属性：
* 速度（speed）
* 体积（size）等等
* 方法移动 move()
* 设置速度 setSpeed(int speed)
* 加速 speedUp()
* 减速 speedDoun()等等
* 在测试类Vehicle中的main()中实例化一个交通工具对象，并通过方法给她初始化speed，size的值并打印出来
* 另外调用加速减速的方法对速度进行改变*/
public class Test {
    public static void main(String[] args) {
        //创建交通工具对象
        /*Vehicle vehicle = new Vehicle();
        vehicle.setSpeed(0);
        vehicle.setSize(5);*/
        Vehicle vehicle = new Vehicle(0,5);

        vehicle.move();
        System.out.println("初始速度为：" + vehicle.getSpeed());
        System.out.println("车身长度为：" + vehicle.getSize());

        vehicle.speedUp(20);
        vehicle.speedUp(40);
        vehicle.speedUp(60);
        System.out.println("speedUp：" + vehicle.getSpeed());
        vehicle.speedDown(100);
        System.out.println("speedDown：" + vehicle.getSpeed());
    }
}

class Vehicle{
    private int speed;
    private int size;

    public Vehicle(){}
    public Vehicle(int speed,int size){
        this.speed = speed;
        this.size = size;
    }

    public void setSpeed(int speed){
        this.speed = speed;
    }
    public int getSpeed(){
        return speed;
    }
    public void setSize(int size){
        this.size = size;
    }
    public int getSize(){
        return size;
    }

    public void move(){
        System.out.println("交通工具：公共汽车，起步行驶");;
    }
    public void speedUp(int addSpeed){
        if(this.getSpeed() + addSpeed <= 80) {
            this.setSpeed(this.getSpeed() + addSpeed);
        }else{
            this.setSpeed(80);
        }
    }
    public void speedDown(int subSpeed){
        if(this.getSpeed() >= subSpeed) {
            this.setSpeed(this.getSpeed() - subSpeed);
        }else{
            this.setSpeed(0);
        }
    }
}

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 2、编写Java程序模拟简单的计算器：this.get/set，返回值类型，return

*编写Java程序模拟简单的计算器
定义名为Number的类，其中有两个整型数据成员n1和n2，声明为私有
编写构造方法赋予n1和n2初始值
再为该类定义加addition、减subtration、乘multiplication、除division等公有实例方法
分别对两个成员变量进行加减乘除的运算*/
public class Test {
    public static void main(String[] args) {
        Number number = new Number(10,0);

        number.addition();
        int sub = number.subtration();
        System.out.println(number.getN1() + "-" + number.getN2() + "=" + sub);
        number.multiplication();
        number.division();
    }
}

class Number{
    private int n1;
    private int n2;

    public Number() {
    }
    public Number(int n1, int n2) {
        this.n1 = n1;
        this.n2 = n2;
    }

    public int getN1() {
        return n1;
    }
    public void setN1(int n1) {
        this.n1 = n1;
    }
    public int getN2() {
        return n2;
    }
    public void setN2(int n2) {
        this.n2 = n2;
    }

    //可以返回值类型是void，也可以是int
    public void addition(){
        //int result = n1 + n2;
        //System.out.println(n1 + "+" + n2 + "=" + result);
        System.out.println(this.getN1() + "+" + this.getN2() + "=" + (this.getN1() + this.getN2()));
    }
    public int subtration(){
        return n1 - n2;
    }
    public  void  multiplication(){
        int result = n1 * n2;
        System.out.println(this.getN1() + "*" + this.getN2() + "=" + result);
    }
    public void  division(){
        if(n2 == 0){
            System.out.println("除数不能为0");
            return;
        }
        int result = n1/n2;
        System.out.println(this.getN1() + "+" + this.getN2() + "=" + result);
    }
}

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3、编写程序用于显示人的姓名和年龄：this.get/set

/*编写程序用于显示人的姓名和年龄
定义一个人类person该类中应该有两个私有属性姓名name和年龄age
定义构造方法用来初始化数据成员。再定义显示方法display()将姓名和年龄打印出来
在main方法中创建人类的实例然后将信息显示*/
public class Test {
    public static void main(String[] args) {
        Person person = new Person();
        person.setName("张三");
        person.setAge(20);
        person.display();

        Person person1 = new Person("李四",30);
        person1.display();

        Person person2 = new Person();
        person2.display();
    }
}

class Person{
    
    public void display(){
        System.out.println("姓名：" + this.getName() + "，年龄：" + this.getAge());
        //System.out.println("姓名：" + this.name + "，年龄：" + this.age);
        //System.out.println("姓名：" + this.name() + "，年龄：" + this.age());
    }

    private String name;
    private int age;

    public Person() {    }
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
}

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4、定义一个时间类，get/set，if()，创建对象，加减操作，加减运算

/*定义名为MyTime的类，其中应有三个整型成员时hour分minute秒second
为了保证数据的安全性这三个成员变量应声明为私有
为MyTime类定义构造方法以方便创建对象时初始化成员变量
再定义display方法用于将时间信息打印出来
为MyTime类添加以下方法
    addSecond(int sec)
    addMinute(int min)
    addHour(int hou)
    subSecond(int sec)
    subMinute(int min)
    subHour(int hou)
分别对时分秒进行加减运算*/
public class Test {
    public static void main(String[] args) {
        //创建时间的对象，初始时间，将信息输出
        MyTime time1 = new MyTime();
        time1.display();

        MyTime time2 = new MyTime(23,55,50);
        System.out.println("time2:");
        time2.display();

        //加减操作
        time2.addSecond(5);
        time2.display();

        time2.addSecond(55);
        time2.display();

        time2.addSecond(5210);
        time2.display();
    }
}

class MyTime {
    private int hour;
    private int minute;
    private int second;

    public MyTime() {
    }
    public MyTime(int hour, int minute, int second) {
        this.hour = hour;
        this.minute = minute;
        this.second = second;
    }

    public int getHour() {
        return hour;
    }
    public void setHour(int hour) {
        this.hour = hour;
    }
    public int getMinute() {
        return minute;
    }
    public void setMinute(int minute) {
        this.minute = minute;
    }
    public int getSecond() {
        return second;
    }
    public void setSecond(int second) {
        this.second = second;
    }
    
    //加秒（秒的范围是0-59）
    public void addSecond(int sec){
        int newSec = this.getSecond() + sec;
        if(newSec < 60) {
            setSecond(newSec);
        }else if(newSec >= 60){
            int min = newSec / 60;
            addMinute(min);
            setSecond(newSec % 60);
        }
    }
    //加分（分的范围是0-59）
    public void addMinute(int min){
        int newMin = this.getMinute() + min;
        if(newMin < 60) {
            setMinute(newMin);
        }else if(newMin >= 60){
            int hou = newMin / 60;
            addHour(hou);
            setMinute(newMin % 60);
        }
    }
    //加时（时的范围是0-23）
    public void addHour(int hou){
        int newHou = this.getHour() + hou;
        if(newHou < 24){
            setHour(newHou);
        }else if(newHou >= 24){
            setHour(newHou % 24);
        }
    }
    //减秒
    public void subSecond(int sec){}
    //减分
    public void subMinute(int min){}
    //减时
    public void subHour(int hou){}
    
    //打印
    public void display() {
        System.out.println(this.getHour() + "时" + this.getMinute() + "分" + this.getSecond() + "秒");
    }
}

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//即使再小的帆也能远航