Flow Free类游戏开发：点击非白色圆形仍触发错误提示问题排查

First, let's address the immediate issue: why clicking non-white circles is triggering the "error" message.

Root Cause #

Your colors list is 0-indexed (starts at 0), but when you calculate index1 and index2, you're adding +1 to make them 1-based. Then you use this 1-based index to access colors, which means you're checking the color of the next circle in the list, not the one you clicked.

For example:

• If you click the second circle (0-based index 1, color blue), index1 becomes 1+1=2.
• colors.get(2) is white, so your code incorrectly prints "error".

Fix Option 1: Use 0-based Indices Everywhere #

Remove the +1 when setting index1 and index2, so they match the 0-based indices of both circles and colors:

if(counter % 2 == 1) {
    index1 = circles.indexOf(shape); // No +1
    if(Color.WHITE.equals(colors.get(index1))) {
        counter--;
        System.out.println("error");
    }
} else {
    index2 = circles.indexOf(shape); // No +1
    if(checkLinearity(index1, index2)) {
        // Draw your rectangle here
    }
}

Adjust the checkLinearity Function #

Since we're now using 0-based indices, update the function to correctly check for same row (the original logic had a bug even for 1-based):

public static boolean checkLinearity(int index1, int index2){
    // Check if same column
    if((index1 % 5) == (index2 % 5)) {
        return true;
    }
    // Check if same row (0-based: integer division by 5 gives row number)
    if((index1 / 5) == (index2 / 5)) {
        return true;
    }
    return false;
}

Fix Option 2: Keep 1-based Indices (Adjust Color Access) #

If you prefer to keep index1 and index2 as 1-based, subtract 1 when accessing the colors list:

if(counter % 2 == 1) {
    index1 = circles.indexOf(shape) + 1;
    if(Color.WHITE.equals(colors.get(index1 - 1))) { // Subtract 1 here
        counter--;
        System.out.println("error");
    }
}

Note: The original checkLinearity function still has a bug for same-row checks—Math.abs(index1-index2) <5 isn't reliable (e.g., indices 5 and 6 would incorrectly return true). Use the adjusted version from Option 1 if you go this route.

Bonus: Improve Efficiency with Indexed Loop #

Instead of using circles.indexOf(shape) (which scans the entire list each time), loop with an index directly to get the position of the clicked shape:

public void mouseClicked(MouseEvent e) {
    int x = e.getX();
    int y = e.getY();
    for (int i = 0; i < circles.size(); i++) {
        Shape shape = circles.get(i);
        if (shape.contains(x, y)) {
            counter++;
            if(counter % 2 == 1) {
                index1 = i; // Directly use the loop index
                if(Color.WHITE.equals(colors.get(i))) {
                    counter--;
                    System.out.println("error");
                }
            } else {
                index2 = i;
                if(checkLinearity(index1, index2)) {
                    // Draw rectangle logic here
                }
            }
            break; // Exit loop after finding the clicked shape
        }
    }
}

This is faster and avoids any potential issues with indexOf (though in your case, since each shape is unique, it works—but indexed loops are better practice here).

内容的提问来源于stack exchange，提问作者shuryu sd