java - 编译程序时出现堆栈溢出错误

Question

我正在尝试使用继承来创建和关联四个类，例如形状、圆形、矩形和正方形，如下所示。

但是，当我编译程序时，显示错误消息，如下所示:

Exception in thread "main" java.lang.StackOverflowError
    at Square.setSide(Square.java:20)

我不知道为什么会这样。下面附上我的编码

方形.java

public class Square extends Rectangle {
    public Square() {
        super();
    }

public Square(double side) {
    super(side, side);
}

public Square(double side, String color, boolean filled) {
    super(side, side, color, filled);  
}

public double getSide() {
    return getSide();
}

public void setSide(double side) {
    this.setSide(side);
}

public void setWidth(double side) {
    this.setWidth(getWidth());
}

public void setLength(double side) {
    this.setLength(getLength());
}

public String toString() {
    return "Square[Rectangle" + "[" + "Shape" + "[" + "color=" + getColor() + "," + "filled=" + isFilled() + "]," + "width=" + getWidth() + "," + "length=" + getLength() + "]";
}
}

矩形.java

public class Rectangle extends Shape {

private double length;
private double width;

public Rectangle() {
    this.length = 1.0;
    this.width = 1.0;
}

public Rectangle(double length, double width)
{
    this.length = length;
    this.width = width;
}

public Rectangle(double width, double length, String color, boolean filled) {
    super(color, filled);
    this.width = width;
    this.length = length;
}

public double getWidth()
{
    return this.width;
}

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

public double getLength()
{
    return this.length;
}

public void setLength(double length)
{
    this.length = length;
}

public double getArea() {
    return length * width;
}

public double getPerimeter() {
    return 2*length + 2*width;
}

public String toString() {
    return "Rectangle[Shape" + "[color=" + getColor() + "," + "filled=" + isFilled() + "]," + "width=" + width + "," + "length=" + length + "]";
}




}

圆.java

public class Circle extends Shape {

    // TODO Auto-generated method stub
    private double radius;


    public Circle() {
        this.radius = 1.0;

    }

    public Circle(double radius) {
        this.radius = radius;
    }

    public Circle(double radius, String color, boolean filled) {
        super(color,filled);
        this.radius = radius;
    }

    public double getRadius() {
        return this.radius;
    }

    public void setRadius(double radius) {
        this.radius = radius;
    }

    public double getArea() {
        return radius * radius * Math.PI;
    }

    public double getPerimeter() {
        return 2 * Math.PI * radius;
    }

    public String toString() {
        return "Circle[Shape" + "[color=" + getColor() + "," + "filled=" + isFilled() + "]," + "radius=" + radius + "]";
    }



}

形状.java

public class Shape {
private String color;
private boolean filled;

public Shape() {
    this.color = "red";
    this.filled = true;
}

public Shape(String color, boolean filled) {
    this.color = color;
    this.filled = filled;
}

public String getColor() {
    return this.color;
}

public void setColor(String color) {
    this.color = color;
}

public boolean isFilled() {
    return this.filled;
}

public void setFilled(boolean filled) {
    this.filled = filled;
}

public String toString() {
    return "Shape[color=" + color + "," + "filled=" + filled + "]";
}

}

如果有人能帮助我的话那就更好了。非常感谢!

P.S 输出应该是这样的

//Need copy the below codings for output


public class TestMain {
   public static void main(String[] args) {
      /* Test Shape class */
      // Test constructors and toString()
      Shape s1 = new Shape();
      System.out.println(s1);  // toString()
      Shape s2 = new Shape("green", false);
      System.out.println(s2);  // toString()
      // Test Setters and Getters
      s1.setColor("blue");
      s1.setFilled(true);
      System.out.println(s1);  // toString()
      System.out.println("Color is: " + s1.getColor());
      System.out.println("Filled is: " + s1.isFilled());

  /* Test Circle class */
  // Test constructors and toString()
  Circle c1 = new Circle();
  System.out.println(c1);
  Circle c2 = new Circle(1.1);
  System.out.println(c2);
  Circle c3 = new Circle(2.2, "green", false);
  System.out.println(c3);
  // Test Setters and Getters
  c1.setColor("orange");  // superclass
  c1.setFilled(true);     // superclass
  c1.setRadius(8.8);
  System.out.println(c1);
  System.out.println("Color is: " + c1.getColor());  // superclass
  System.out.println("Filled is: " + c1.isFilled()); // superclass
  System.out.println("Radius is: " + c1.getRadius());
  System.out.printf("Area is: %.2f%n", c1.getArea());
  System.out.printf("Perimeter is: %.2f%n", c1.getPerimeter());

  /* Test Rectangle class */
  // Test constructors and toString()
  Rectangle r1 = new Rectangle();
  System.out.println(r1);
  Rectangle r2 = new Rectangle(1.1, 2.2);
  System.out.println(r2);
  Rectangle r3 = new Rectangle(3.3, 4.4, "green", false);
  System.out.println(r3);
  // Test setters and getters
  r1.setWidth(5.5);
  r1.setLength(6.6);
  r1.setColor("orange");  // superclass
  r1.setFilled(true);     // superclass
  System.out.println(r1);
  System.out.println("Color is: " + r1.getColor());  // superclass
  System.out.println("Filled is: " + r1.isFilled()); // superclass
  System.out.println("Length is: " + r1.getLength());
  System.out.println("Width is: " + r1.getWidth());
  System.out.printf("Area is: %.2f%n", r1.getArea());
  System.out.printf("Perimeter is: %.2f%n", r1.getPerimeter());

  /* Test Square class */
  // Test constructor and toString()
  Square sq1 = new Square();
  System.out.println(sq1);
  Square sq2 = new Square(1.1);
  System.out.println(sq2);
  Square sq3 = new Square(2.2, "green", false);
  System.out.println(sq3);
  // Test Setters and Getters
  sq1.setSide(3.3);
  sq1.setColor("orange");  // superclass
  sq1.setFilled(false);    // superclass
  System.out.println(sq1);
  System.out.println("Color is: " + sq1.getColor());   // superclass
  System.out.println("Filled is: " + sq1.isFilled());  // superclass
  System.out.println("Side is: " + sq1.getSide());

  sq1.setWidth(4.4);  // overridden
  System.out.println(sq1);
  System.out.println("Width is: " + sq1.getWidth());   // superclass
  sq1.setLength(5.5);  // overridden
  System.out.println(sq1);
  System.out.println("Length is: " + sq1.getLength()); // superclass

  System.out.printf("Area is: %.2f%n", sq1.getArea());
  System.out.printf("Perimeter is: %.2f%n", sq1.getPerimeter());


  }
}

输出

Shape[color=red,filled=true]
Shape[color=green,filled=false]
Shape[color=blue,filled=true]
Color·is:·blue
Filled·is:·true
Circle[Shape[color=red,filled=true],radius=1.0]
Circle[Shape[color=red,filled=true],radius=1.1]
Circle[Shape[color=green,filled=false],radius=2.2]
Circle[Shape[color=orange,filled=true],radius=8.8]
Color·is:·orange
Filled·is:·true
Radius·is:·8.8
Area·is:·243.28
Perimeter·is:·55.29
Rectangle[Shape[color=red,filled=true],width=1.0,length=1.0]
Rectangle[Shape[color=red,filled=true],width=1.1,length=2.2]
Rectangle[Shape[color=green,filled=false],width=3.3,length=4.4]
Rectangle[Shape[color=orange,filled=true],width=5.5,length=6.6]
Color·is:·orange
Filled·is:·true
Length·is:·6.6
Width·is:·5.5
Area·is:·36.30
Perimeter·is:·24.20
Square[Rectangle[Shape[color=red,filled=true],width=1.0,length=1.0]]
Square[Rectangle[Shape[color=red,filled=true],width=1.1,length=1.1]]
Square[Rectangle[Shape[color=green,filled=false],width=2.2,length=2.2]]
Square[Rectangle[Shape[color=orange,filled=false],width=3.3,length=3.3]]
Color·is:·orange
Filled·is:·false
Side·is:·3.3
Square[Rectangle[Shape[color=orange,filled=false],width=4.4,length=4.4]]
Width·is:·4.4
Square[Rectangle[Shape[color=orange,filled=false],width=5.5,length=5.5]]
Length·is:·5.5
Area·is:·30.25
Perimeter·is:·22.00

Answer 1

您的 StackOverFlow 错误来自 Square 类

public class Square extends Rectangle {

private double side;

public Square() {
    super();
}

public Square(double side) {
    super(side, side);
}

public Square(double side, String color, boolean filled) {
    super(side, side, color, filled);  
}

public double getSide() {
    return this.side;
}

public void setSide(double side) {
    this.side = side;
}

public void setWidth(double side) {
    super.setWidth(getWidth());
}

public void setLength(double side) {
    super.setLength(getLength());
}

public String toString() {
    return "Square[Rectangle" + "[" + "Shape" + "[" + "color=" + getColor() + "," + "filled=" + isFilled() + "]," + "width=" + getWidth() + "," + "length=" + getLength() + "]";
}
}

方法setSide、setWidth和setLength都在调用自身，导致无限循环超过Java分配的调用堆栈内存量虚拟机。

不使用此方法，而是引用 Square 类，使用 super.setSide 来调用父类矩形中的方法。