变量可能尚未初始化...如何增加范围？[重复]

Question

我一直收到一个错误：

error: variable aryResponse might not have been initialized
                if(answers.charAt(i) == aryResponse[i].charAt(i))

我想这是因为我在while循环中初始化变量。但是我不知道如何解决这个问题？

当我需要它初始化为循环给定的值时，如何增加变量的范围？

import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

class ExamAnalysis
{
    public static void main(String[] args) throws FileNotFoundException
    {
                    Scanner in = new Scanner(System.in);
                    System.out.println("Welcome to Exam Analysis.  Let's begin ...");
                    System.out.println();
                    System.out.println();
                    System.out.print("Please type the correct answers to the exam questions, one right af$
                    String answers = in.nextLine();
                    int answersLength = answers.length();
                    System.out.println();
                    System.out.print("What is the name of the file containing each student's responses to$
                    String temp = in.nextLine();
                    File file = new File(temp);
                    Scanner in2 = new Scanner(file);
/*Code Relevant To This Question Begins Here */
                    int lines = 0;
                    String[] aryResponse;
                    while (in2.hasNextLine())
                    {
                            String line = in2.nextLine();
                            aryResponse = new String[lines];
                            aryResponse[lines] = line;
                            System.out.println("Student #" + lines + "'s responses:  " + line);
                            lines++;
                    }
                    System.out.println("We have reached \"end of file!\"");
                    System.out.println();
                    System.out.println("Thank you for the data on " + lines + " students.  Here's the ana$
                    int[] aryCorrect = new int[lines];
                    for (int i = 0; i < answersLength; i++)
                    {
                            if(answers.charAt(i) == aryResponse[i].charAt(i))
                            {
                                    aryCorrect[i] ++;
                            }
                    }
       }
}

Answer 1

只需在循环外初始化它

String[] aryResponse=null;

现在将内存分配给aryResponse内部循环

aryResponse = new String[n]; //n is the size of array

Answer 2

如果我理解了你的代码，arySolutions有几行，如果变量从来没有初始化的同时循环，这意味着你有0行，所以，这将是足够做两件事情：

1-将响应初始化为空：

String[] aryResponse = null;

2-在while循环的末尾添加此行：

if(aryResponse == null) aryResponse = new String[0];

Answer 3

改变这个

String[] aryResponse;

到

String[] aryResponse = null;

记住测试aryResponse不是null，

if (aryResponse != null) {
  for (int i = 0; i < answersLength; i++) {
    if (answers.charAt(i) == aryResponse[i].charAt(i)) { // what is this testing?
      aryCorrect[i]++;
    }
  }
}

这是必要的，因为

while (in2.hasNextLine()) { // <-- might not be true
  // so this doesn't happen.
}