java - 计算一个方法被调用的次数？

Question

我正在尝试计算方法被调用的次数。我现在有 3 个类，Circle.java、Picture.java 和 PictureTest.java

circle.java里面有;

public class Circle
{
    private int diameter;
    private int xPosition;
    private int yPosition;
    private String color;
    private boolean isVisible;
    private int instances;

    /**
     * Create a new circle at default position with default color.
     */
    public Circle()
    {
        diameter = 30;
        xPosition = 20;
        yPosition = 60;
        color = "blue";
        isVisible = false;
        instances = 0;
        instances++;
        System.out.println(instances);
    }

在Picture.java中:

public class Picture
{
    private Circle sun;

    /**
     * Constructor for objects of class Picture
     */
    public Picture()
    {
        // nothing to do... instance variables are automatically set to null
    }

    /**
     * Draw this picture.
     */
    public void draw()
    {    
        sun = new Circle();
        sun.changeColor("yellow");
        sun.moveHorizontal(180);
        sun.moveVertical(-10);
        sun.changeSize(60);
        sun.makeVisible();

        sun = new Circle();
        sun.changeColor("yellow");
        sun.moveHorizontal(180);
        sun.moveVertical(-10);
        sun.changeSize(60);
        sun.makeVisible();

        sun = new Circle();
        sun.changeColor("yellow");
        sun.moveHorizontal(180);
        sun.moveVertical(-10);
        sun.changeSize(60);
        sun.makeVisible();
    }

PictureTest.java 是 main 所在的地方:

public class PictureTest
{
   public static void main(String[] args)
   {
        Picture p = new Picture();
        p.draw();

   }
}

当我运行它时，它打印的不是 3 因为有三个太阳，而是打印:

1
1
1

我不完全确定为什么会这样，但我认为这可能与我从 Circle 类打印的事实有关，所以每次创建圆时它都会打印 1。我试过更改它，以便它从 PictureTest 中的主要打印实例，但我无法让它工作。

谢谢!

Answer 1

instances = 0;
instances++;

instances 将始终等于 1。

您需要做的是将instances 设为static 变量。

public class Circle
{
    public static int instances = 0;
}

然后在你的构造函数类中

instances ++;