Question

我的程序中找不到任何问题。每次用户输入一个数字时，我希望它将其保存在数组A上，但是当用户尝试键入第二个数字时，会出现NumberFormatException错误。

Exception in thread "main" java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:470)
at java.lang.Integer.parseInt(Integer.java:499)
at practice.test(end.java:22)
at end.main(end.java:7)

以下是该计划：

import java.io.*;

class end {
    public static void main(String[] args) throws IOException {
        practice obj = new practice();
        obj.test();
    }
}

class practice {
    void test() throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        int A[] = new int[5];
        String x;
        int a, b, c, i = 0;
        for(i = 0; i < 5; i++) {
            System.out.println("Insert a number");
            x = br.readLine();
            A[i] = Integer.parseInt(x);
        }
    }
}

Answer 1

只要输入数字，代码就可以正常工作。如果输入空字符串，它将显示您发布的错误。

可能需要add a check for empty string。

if(!x.isEmpty()){
               A[i] = Integer.parseInt(x);
            }

public class end {

    public static void main(String[] args) throws IOException {
        practice obj = new practice();
        obj.test();
    }
}

class practice {
    void test() throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        int A[] = new int[5];
        String x;
        int a, b, c, i = 0;
        for (i = 0 ; i < 5 ; i++) {
            System.out.println("Insert a number");
            x = br.readLine();
            A[i] = Integer.parseInt(x);
        }

        for (i = 0 ; i < 5 ; i++) {
            System.out.println(A[i]);
        }
    }
}

<强>输出

Insert a number
2
Insert a number
3
Insert a number
4
Insert a number
5
Insert a number
6
User input
2
3
4
5
6

Answer 2

看起来你试图从Stacktrace中输入一个空字符串，你应该检查输入是否为空......

 InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        int A[] = new int[5];
        String x;
        int a, b, c, i = 0;
        for(i = 0; i < 5; i++) {
            System.out.println("Insert a number");
            x = br.readLine();
            //check if input is empty
            if(!x.isEmpty()){
               A[i] = Integer.parseInt(x);
            }
        }

线程“main”中的异常java.lang.NumberFormatException：对于输入字符串：“”Array

2 个答案: