Question

我正在迭代圆圈（r）的可能半径，当我找到潜在的候选人时，我基本上想把它们推到一个堆栈上。我只需要记住最后两个半径和它们对应的圆的颜色，所以我创建了四个整数来存储这些变量。但是，我包含的print语句总是为两个变量产生值0。

 //small stack to hold values of previous circles
            int small_radius    =   0;
            int small_color     =   0;
            int med_radius      =   0;
            int med_color       =   0; 
            //iterate through possible radii       
            while (r<max){
                //check for possibility of a circle
                if(detectCircle(x,y,r,img,g)){
                    //confirm it is a circle and store its color
                    int large_color = confirmCircle(x,y,r,img,g);
                    if(large_color != -1){
                        //if it is a circle, compare the medium circle against the current one and the small one
                        //check if the current circle and small circle do not immediately surround the medium circle
                        boolean matches_small = (med_radius-1 == small_radius && med_color == small_color);
                        boolean matches_large = (r-1 == med_radius && large_color == med_color);
                        if(!matches_small && !matches_large){
                            //if it is a circle of single line thickness, draw it
                            System.out.println("med_radius: "+med_radius+" small_radius: "+small_radius);
                            drawCircle(x,y,r,img,g);
                        }
                        //now push the current circle onto the stack.
                        small_radius = med_radius;
                        small_color  = med_color;
                        med_radius   = r;
                        med_color    = large_color;  
                    }
                }
                r++;
            }

编辑：对于那些想知道confirmCircle是什么样的人来说，就是这样，但它不应该有所作为。

 static int confirmCircle(int cx, int cy, int r, BufferedImage img, Graphics2D g) {

    int color = img.getRGB(cx,cy+r);

    int f = 1-r;
    int ddF_x = 1;
    int ddF_y = -2 * r;
    int x = 0;
    int y = r;


    while(x < y) {
        if(f >= 0) {
            y--;
            ddF_y += 2;
            f += ddF_y;
        }
        x++;
        ddF_x += 2;
        f += ddF_x;

        if(img.getRGB(cx+x,cy+y) != color){color = -1;}
        if(img.getRGB(cx-x,cy+y) != color){color = -1;}
        if(img.getRGB(cx+x,cy-y) != color){color = -1;}
        if(img.getRGB(cx-x,cy-y) != color){color = -1;}
        if(img.getRGB(cx+y,cy+x) != color){color = -1;}
        if(img.getRGB(cx-y,cy+x) != color){color = -1;}
        if(img.getRGB(cx+y,cy-x) != color){color = -1;}
        if(img.getRGB(cx-y,cy-x) != color){color = -1;}
    }
    return color;
}

Answer 1

此示例中没有代码分配给四个变量中的任何一个。

如果您正在confirmCircle()内进行分配，那么问题在于，当您在Java中传递值时，您期望int是传递引用。

换句话说：

int a = 4;

public void changeA(int someVar) {
    someVar++;
}

changeA(a);
System.out.println(a);  //prints 4, not 5.

java中的变量没有在循环中保存它们的值

1 个答案: