java - Java 运行时错误：线程“主”java.lang.NullPointerException 中的异常

Question

我正在使用 java 解决算法问题并得到这个运行时错误：

Exception in thread "main" java.lang.NullPointerException
    at java.io.FileOutputStream.<init>(FileOutputStream.java:203)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:101)
    at java.io.FileWriter.<init>(FileWriter.java:63)
    at Main.main(Main.java:50)

我对java没有太多经验，所以我在这里分享我的代码：

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Main {

    // Complete the breakingRecords function below.
    static int maxXv(int[] gymXp, int strength) {
        int temp = 0;
        int xp = 0;
        int max = gymXp[0];
        
        for (int i = 0; i < gymXp.length; i++){ 
             if (gymXp[i] > max) {
                 max = gymXp[i];
             }
        }
        int digiSum = 0;
        int num = 0;
        for (int j = 0; j < gymXp.length; j++){
            if (j == gymXp.length-1){
                xp += strength*gymXp[j];
                System.out.println("Battling Cuz im last, strength "+strength+ " xp="+ xp);
                continue;
            }
            if (gymXp[j]==max){
                xp += strength*gymXp[j];
                System.out.println("Battling Cuz im biggest, strength "+strength+ " xp="+ xp);
                continue;
            }
            num = strength;
            digiSum = 0;
            while(num!=0){
                digiSum = digiSum + num % 10;
                num = num/10;
            }
            strength += digiSum*digiSum*digiSum;
            System.out.println("trained and now , strength "+strength+ " xp="+ xp);
        }
        return xp;
    }

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int n = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
        
        int strength = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        int[] gymXp = new int[n];

        String[] xpItems = scanner.nextLine().split(" ");
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        for (int i = 0; i < n; i++) {
            int xpItem = Integer.parseInt(xpItems[i]);
            gymXp[i] = xpItem;
        }

        int result = maxXv(gymXp, strength);

        bufferedWriter.write(String.valueOf(result));

        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close();
    }
}

我不明白错误是什么，当我在hackerrank上运行它时它工作得很好，但它给了我在codechef上的上述错误（这是我解决这个问题的地方）。

请帮助我，因为我已经被这个问题困了几个小时

标签： java