面向对象练习题

class Demo{
    int a;
    int b;
    public Demo(int a,int b){
        this.a = a;
        this.b = b;
    }
    public int add(){
        return a+b;
    }
}

class Test{
    public static void main(String[] args){

        Demo d = new Demo(1,3);//将1和3 赋值给成员变量
        int result = d.add();//调用add,计算成员变量的和
        System.out.println(result);//4
    }
    
}

class Rectangle{
    int length;//长
    int width;//宽
    public int getZhouChang(){//求周长
        return 2*(length+width);
    }
    public int getArea(){
        return length*width;
    }
    public Rectangle(){}
    public Rectangle(int length,int width){
           this.length = length;
           this.width = width;
    }
}

class Test2{
    public static void main(String[] args){
        Rectangle r = new Rectangle(12,3);//创建一个长12,宽3的长方形
        int zhouChang = r.getZhouChang();
        int area = r.getArea();
        System.out.println(zhouChang);
        System.out.println(area);
    }

}

class Employee{
    private String name;
    private int age;
    private int id;
    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;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
    public Employee(String name, int age, int id) {
		super();
		this.name = name;
		this.age = age;
		this.id = id;
	}
    public Employee(){}
    
}

class Test3{
    public static void main(String[] args){
        Employee e1 = new Employee("张三",12,1);
        Employee e2 = new Employee();
        e2.setName("李四");
        e2.setAge(19);
        e2.setId(2);
        
    }
}

class MyMath{
    int a;
    int b;
    public MyMath(int a,int b){
        this.a = a;
        this.b = b;
    }
    public int add(){
        return a+b;
    }
    public int sub(){
        return a-b;
    }
    public int mul(){
        return a*b;
    }
    public int div(){
        return a/b;
    }

}

class Circle{
    double r;
    public double getPermeter(){
        return 3.14*r*2;
    }
    public double getArea(){
        return 3.14*r*r;
    }


}