java/w4/Rectangle.java

package com.shape;

public class Rectangle extends Shape {
    private double width;    // 宽度
    private double height;   // 高度

    public Rectangle(double width, double height) {
        if (width <= 0 || height <= 0) {
            throw new IllegalArgumentException("长和宽必须大于0");
        }
        this.width = width;
        this.height = height;
    }

    public double getWidth() {
        return width;
    }

    public void setWidth(double width) {
        if (width > 0) this.width = width;
    }

    public double getHeight() {
        return height;
    }

    public void setHeight(double height) {
        if (height > 0) this.height = height;
    }

    @Override
    public double getArea() {
        return width * height;   // 长 × 宽
    }
}