我需要验证用户输入的字符串的索引是否有效

Question

当用户输入单词时，系统会提示他们输入子字符串的第一个和第二个索引。我已经排序了这么多，但是当我尝试验证使用下面的 if 语句输入的索引时，我收到了有关这些 if 语句的错误，

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        String inputString;

        int startIndex;

        int endIndex;

        System.out.println("Enter a string : ");

        inputString = scanner.nextLine();

        System.out.println("Enter the first index of the substring : ");

        startIndex = scanner.nextInt();

        if (int startIndex > inputSting.length) {

            System.out.println("Index is not in string length, try again.");

        }

        System.out.println("Enter the second index of the substring : ");

        endIndex = scanner.nextInt();

        if (int endIndex > inputSting.length) {

            System.out.println("Index is not in string length, try again.");

        } 

        char[] ch = new char[endIndex - startIndex + 1];

        inputString.getChars(startIndex, endIndex + 1, ch, 0);

        System.out.println("Output : " + String.valueOf(ch));

    }

}

Answer 1

你的代码绝对不是Java语言。第一的：if (int startIndex > inputSting.length) { .. }您不能在if语句内或比较表达式中声明变量，而且该变量startIndex已经存在。第二：inputSting变量不存在并且它肯定没有属性length。inputString可能是+ string 有方法length()而不是属性的拼写错误。

Answer 2

更改以下内容：int startIndex到startIndex,int endIndex到endIndex,inputSting.length到inputString.length()所以固定代码， public class Main {     public static void main(String[] args) {        Scanner scanner = new Scanner(System.in);        String inputString="";        int startIndex;        int endIndex;        System.out.println("Enter a string : ");        inputString = scanner.nextLine();        System.out.println("Enter the first index of the substring : ");        startIndex = scanner.nextInt();        if ( startIndex > inputString.length()) {            System.out.println("Index is not in string length, try again.");        }        System.out.println("Enter the second index of the substring : ");        endIndex = scanner.nextInt();        if ( endIndex > inputString.length()) {            System.out.println("Index is not in string length, try again.");        }        char[] ch = new char[endIndex - startIndex + 1];        inputString.getChars(startIndex, endIndex + 1, ch, 0);        System.out.println("Output : " + String.valueOf(ch));    } }