Question

java 上机试验：类与对象的试验

定义一个名为MyRectangle的矩形，类中有四个私有整形域，分别是矩形的左上角坐标（xUp，yUp）和右下角坐标（xDowm，yDown）；类中定义没有参数的构造方法和有四个int参数的构造方法，用来初始化类对象。类中还有以下方法：getW()——计算矩形的宽度；getH()——计算矩形的高度；area()——计算矩形的面积；toString()——把矩形的宽高面积等信息作为字符串返回。编写程序使用MyRectangle类。

Answer 1

public class MyRectangle {

//四个私有变量
private int xUp, yUp;
private int xDown, yDown;

//空构造函数
public MyRectangle() {

}

//带有四个参数的构造函数，并初始化
public MyRectangle(int xup, int yup, int xdown, int ydown) {
this.xUp = xup;
this.yUp = yup;
this.xDown = xdown;
this.yDown = ydown;
}

//获取宽度
public int getW() {
return this.xDown - this.xUp;
}

//获取高度
public int getH() {
return this.yUp - this.yDown;
}

//计算面积
public int area() {
return this.getW() * this.getH();
}

//重写toString返回宽度、高度、面积
public String toString() {
return ("width=: " + this.getW() + "\nheight=: " + this.getH() + "\narea=: " + this.area() + "");
}

public static void main(String[] args) {
//实例化对象
MyRectangle myrectangle = new MyRectangle(10, 30, 20, 10);
//打印输出
System.out.println(myrectangle);
}
}
测试结果：
width=: 10
height=: 20
area=: 200

Answer 2

public class MyRectangle {
private Integer xUp;
private Integer yUp;

private Integer xDown;
private Integer yDown;

public MyRectangle(){

}

public MyRectangle(Integer x1,Integer y1,Integer x2,Integer y2){
this.xUp = x1;
this.yUp = y1;
this.xDown = x2;
this.yDown = y2;
}

public Integer getW(){
return xDown - xUp;
}

public Integer getH(){
return yDown - yUp;
}

public Integer area(){
return this.getW() * this.getH();
}

public String toString(){
return "宽度为："+this.getW()+"\n高度为："+this.getH()+"\n面积为："+this.area();
}

public static void main(String[] args) {
MyRectangle myRectangle = new MyRectangle(0,0,15,20);
System.out.println(myRectangle.toString());
}
}

Answer 3

自己动手丰衣足食