从控制台的一行中读取整数和字符串 [英] Read integers and strings from a single line of a console

问题描述

问题是这样的：

我有两个程序从控制台以不同方式获取输入：
1）

Scanner input = new Scanner(System.in);
    int temp1 = input.nextInt();
    input.nextLine();
    String str = input.nextLine();
    int temp2 = Integer.parseInt(str);
    int total = temp1+temp2;

    System.out.println(total);

2）

 Scanner input = new Scanner(System.in);
    int temp1 = input.nextInt();
 // input.nextLine();
    String str = input.nextLine();
    int temp2 = Integer.parseInt(str);
    int total = temp1+temp2;

    System.out.println(total);

在第一种情况下，1在2条不同的行中输入

In 1st case 1 take inputs in 2 different lines like

1
2

so它给出了正确的答案，但是在第二种情况下，我删除了 input.nextLine（）语句以将输入内容放在一行中，例如：

so it gives correct answer but in 2nd case I removed the input.nextLine() statement to take inputs in a single line like:

1 2

它给了我数字格式异常为什么？？并且还建议我如何从控制台的一行中读取整数和字符串。

it gives me number format exception why?? and also suggest me how I can read integers and strings from a single line of a console.

推荐答案

问题是 str 的值是 2 ，并且前导空格不是 parseInt（）的合法语法。您需要跳过输入中两个数字之间的空格，或者将 str 的空格修剪掉，然后解析为 int 。要跳过空格，请执行以下操作：

The problem is that str has the value " 2", and the leading space is not legal syntax for parseInt(). You need to either skip the white space between the two numbers in the input or trim the white space off of str before parsing as an int. To skip white space, do this:

input.skip("\\s*");
String str = input.nextLine();

在之前缩小 str 的空间解析，执行以下操作：

To trim the space off of str before parsing, do this:

int temp2 = Integer.parseInt(str.trim());

您也可以看中一口气阅读这两行内容：

You can also get fancy and read the two pieces of the line in one go:

if (input.findInLine("(\\d+)\\s+(\\d+)") == null) {
    // expected pattern was not found
    System.out.println("Incorrect input!");
} else {
    // expected pattern was found - retrieve and parse the pieces
    MatchResult result = input.match();
    int temp1 = Integer.parseInt(result.group(1));
    int temp2 = Integer.parseInt(result.group(2));
    int total = temp1+temp2;

    System.out.println(total);
}

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