java/w4/Rectangle.java

public class Rectangle extends Shape {
    private double width;
    private double height;
    
    // 构造方法
    public Rectangle(double width, double height) {
        this.width = width;
        this.height = height;
    }
    
    // 实现抽象方法，计算矩形的面积
    @Override
    public double getArea() {
        return width * height;
    }
    
    // getter和setter方法
    public double getWidth() {
        return width;
    }
    
    public void setWidth(double width) {
        this.width = width;
    }
    
    public double getHeight() {
        return height;
    }
    
    public void setHeight(double height) {
        this.height = height;
    }
}