Java实现10×10星号方块并替换指定坐标为O的问题排查

需求 #

• 使用*打印10×10的正方形
• 将ArrayList中Character对象对应的(x,y)坐标位置输出为O而非*，示例坐标为(5,5)、(7,8)、(3,1)，预期输出为指定位置替换为O的10×10方块

现有以下代码运行后输出异常，不符合预期，需排查修正：

Character类代码 #

public class Character {
     int xLocation;
     int yLocation;
    public Character(int x, int y){
        this.xLocation = x;
        this.yLocation = y;
    }
    public int getXLocation(){return xLocation;}
    public int getYLocation(){
        return yLocation;
    }
}

Main类代码 #

import java.util.ArrayList;
public class Main {
    public static void main(String[] args)
    {
        int a = 10;
        
        ArrayList<Character> characters = new ArrayList<>();
        Character character1  = new Character(5,5);
        Character character2  = new Character(7,8);
        Character character3  = new Character(3,1);
        characters.add(character1);
        characters.add(character2);
        characters.add(character3);
        for (int i = 1; i<=a; i++)
        {
            for (int v = 1; v <= a; v++)
            {
                for (int j = 0; j < characters.size(); j++)
                {
                    if (v == characters.get(j).getXLocation() && i == characters.get(j).getYLocation())
                    {
                        System.out.print("O ");
                    }
                    else System.out.print("* ");
                }
                System.out.println();
            }
        }
    }
}

错误输出 #

* * * 
* * * 
* * O 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
O * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* O * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 
* * * 

问题分析 #

1. 循环逻辑错误：原代码在每个坐标位置(v,i)遍历所有Character对象，每个对象都输出一个符号，导致每行打印3个符号（对应3个Character实例），最终输出为10行×30列的内容，完全偏离10×10的需求。
2. 符号判断逻辑错误：应该先默认当前坐标输出*，仅当遍历到匹配的Character坐标时才改为输出O，而非每个Character都独立输出一次符号。

修正后的Main类代码 #

import java.util.ArrayList;
public class Main {
    public static void main(String[] args)
    {
        int a = 10;
        
        ArrayList<Character> characters = new ArrayList<>();
        Character character1  = new Character(5,5);
        Character character2  = new Character(7,8);
        Character character3  = new Character(3,1);
        characters.add(character1);
        characters.add(character2);
        characters.add(character3);
        
        for (int i = 1; i <= a; i++)
        {
            for (int v = 1; v <= a; v++)
            {
                // 默认输出*
                char symbol = '*';
                // 遍历所有Character，检查坐标是否匹配
                for (Character c : characters)
                {
                    if (v == c.getXLocation() && i == c.getYLocation())
                    {
                        symbol = 'O';
                        break; // 找到匹配后无需继续遍历
                    }
                }
                System.out.print(symbol + " ");
            }
            // 每行结束换行
            System.out.println();
        }
    }
}

正确输出示例 #

* * * O * * * * * * 
* * * * * * * * * * 
* * * * * * * * * * 
* * * * * * * * * * 
* * * * O * * * * * 
* * * * * * * * * * 
* * * * * * * * * * 
* * * * * * O * * * 
* * * * * * * * * * 
* * * * * * * * * * 

内容的提问来源于stack exchange，提问作者WHEEW