java如何访问在Try Catch中创建的数组？

Question

我试图在try函数之外访问数组A，但它说找不到符号。如何在try方法之外访问数组A

try {
        String filePath = "//Users/me/Desktop/list.txt";
        int N = 100000;
        int A[] = new int[N];

        Scanner sc = new Scanner(new File(filePath));

        for (int i = 0; i < N; i++)
        {
            A[i] = sc.nextInt();
        }
    } catch (IOException ioe) {
        System.out.println("IOException: " + ioe);
    }

Answer 1

在块外声明并在块内分配：

int A[];

try {
        String filePath = "//Users/me/Desktop/list.txt";
        int N = 100000;
        A = new int[N];

        Scanner sc = new Scanner(new File(filePath));

        for (int i = 0; i < N; i++)
        {
            A[i] = sc.nextInt();
        }
    } catch (IOException ioe) {
        System.out.println("IOException: " + ioe);
    }

Answer 2

您正在运行变量的范围。只能在创建变量的范围内使用该变量。这是相同的情况，例如，当您在方法内部创建变量时，您无法从另一个方法访问该变量

您有两个选项：要么在同一范围内使用变量（try块），要么在该范围外声明变量

选项1：相同范围

try {
  ...
  int A[] = new int[N];
  ...
  // use A here only
} catch (IOException ioe) { ... }
// A is no longer available for use out here

选项2：在外部声明它

int A[] = new int [N];
try {
  ...
} catch( IOException ioe) { ... }
// use A here
// but be careful, you may not have initialized it if you threw and caught the exception!