我的程序出现异常，如何解决此问题？ [英] I Get An Exception With My Program, How Do I Reslolve This Problem?

问题描述

import java.util.*;

public class Array2 {

    static int count;
    static int count1;
    static double sum;
    static double average;

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        System.out.println("Enter the value for the length of array");
        int x = in.nextInt();
        double[] y = new double[x];
        double[] y1 = null;

        for (int i = 0; i < y.length; i++) {
            System.out.println("Enter double variables");
            double z = in.nextDouble();
            y[i] = z;

        }
        for (int i = 0; i < y.length; i++) {

            if (y[i] < 10) {
                count++;

            } else if (y[i] > 10) {

                y[i] = y1[i];

            }

        }

        for (int i = 0; i < y1.length; i++) {
            count1++;
            sum += y1[i];

        }
        average = sum / count1;
        System.out.println(average);

    }

}

我的输出是

输入数组长度的值

8

输入双变量



输入双变量

3.4

输入双变量

10.6

输入双变量

34.5

输入双变量

23.5

输入双变量

2.3

输入双变量



输入双变量

1.5

线程main中的异常java.lang.NullPointerException

在Array2.main（Array2.java:32）

Java结果：1

BUILD SUCCESSFUL（总时间：28秒）

my output is
Enter the value for the length of array
8
Enter double variables
5.6
Enter double variables
3.4
Enter double variables
10.6
Enter double variables
34.5
Enter double variables
23.5
Enter double variables
2.3
Enter double variables
3.5
Enter double variables
1.5
Exception in thread "main" java.lang.NullPointerException
at Array2.main(Array2.java:32)
Java Result: 1
BUILD SUCCESSFUL (total time: 28 seconds)

推荐答案

嗯...

Um...

double[] y1 = null;

并且您不会从那里更改它直到：

And you don't change it from there until:

y[i] = y1[i];

所以...也许你需要为它分配一些空间？也许给它一些价值？

So...perhaps you need to allocate some space to it? And perhaps give it some values?

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