目前没想到好方法,等以后想到了再更新吧

import java.util.Scanner;
public class Main {
    
    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        char[][] array = new char[3][3];
        for(int i = 0 ; i < 3 ; i++) {
            for(int j = 0 ; j < 3 ; j++) {
                array[i][j] = sc.next().charAt(0);
            }
        }
        // 行列斜线分别组成str
        StringBuilder str1 = new StringBuilder();
        str1.append(array[0][0]);
        str1.append(array[0][1]);
        str1.append(array[0][2]);
        StringBuilder str2 = new StringBuilder();
        str2.append(array[1][0]);
        str2.append(array[1][1]);
        str2.append(array[1][2]);
        StringBuilder str3 = new StringBuilder();
        str3.append(array[2][0]);
        str3.append(array[2][1]);
        str3.append(array[2][2]);
        StringBuilder str4 = new StringBuilder();
        str4.append(array[0][0]);
        str4.append(array[1][0]);
        str4.append(array[2][0]);
        StringBuilder str5 = new StringBuilder();
        str5.append(array[0][1]);
        str5.append(array[1][1]);
        str5.append(array[2][1]);
        StringBuilder str6 = new StringBuilder();
        str6.append(array[0][2]);
        str6.append(array[1][2]);
        str6.append(array[2][2]);
        StringBuilder str7 = new StringBuilder();
        str7.append(array[0][0]);
        str7.append(array[1][1]);
        str7.append(array[2][2]);
        StringBuilder str8 = new StringBuilder();
        str8.append(array[0][2]);
        str8.append(array[1][1]);
        str8.append(array[2][0]);
        boolean flag = false;    // 没有结果
        if(str1.toString().equals("KKK") || str2.toString().equals("KKK") || str3.toString().equals("KKK") || str4.toString().equals("KKK") || str5.toString().equals("KKK") || str6.toString().equals("KKK") || str7.toString().equals("KKK") || str8.toString().equals("KKK")) {
            System.out.println("KiKi wins!");
            flag = true;
        } else if(str1.toString().equals("BBB") || str2.toString().equals("BBB") || str3.toString().equals("BBB") || str4.toString().equals("BBB") || str5.toString().equals("BBB") || str6.toString().equals("BBB") || str7.toString().equals("BBB") || str8.toString().equals("BBB")) {
            System.out.println("BoBo wins!");
            flag = true;
        }
        if(!flag) {
            System.out.println("No winner!");
        }
    }
}