Java 如何打印包含indexOf（）方法的信函？注意：应打印字母，而不是索引位置

我想根据索引位置打印一封信。虽然，还有更多的补充，但这里的要求，我知道它涉及字符（）；方法，但如何使用该方法查找以下要求的字符串：从用户输入第二个字符串。输出短语中字符串第一个实例后的字符。如果该字符串不在短语中，则输出一条具有该效果的语句。例如，如果输入s“颠倒”和“d”，那么它应该输出“e”，因此它应该是输入字符后面的字符。另一个例子是，输入是颠倒的，并且执行。输出应为“w”

按如下方式操作：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.print("Enter option: ");
        int option = Integer.parseInt(keyboard.nextLine());
        if (option == 3) {
            System.out.print("Enter phrase: ");
            String phrase = keyboard.nextLine();
            System.out.print("Enter a substring to search after: ");
            String substring = keyboard.next();
            int index;
            if (phrase.length() > substring.length()) {
                index = phrase.indexOf(substring);
                if (index != -1 && index < phrase.length() - substring.length()) {
                    System.out.println(phrase.charAt(index + substring.length()));
                }
                if (index == phrase.length() - substring.length()) {
                    System.out.println("'" + substring + "' is the last substring in '" + phrase + "'");
                }
                if (index == -1) {
                    System.out.print("'" + substring + "' is not in '" + phrase + "'");
                }
            }
        }
    }
}

另一个示例运行：

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: do
w

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: down
'down' is the last substring in 'upside down'

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: x
'x' is not in 'upside down'

另一个示例运行：

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: do
w

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: down
'down' is the last substring in 'upside down'

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: x
'x' is not in 'upside down'

按如下方式操作：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.print("Enter option: ");
        int option = Integer.parseInt(keyboard.nextLine());
        if (option == 3) {
            System.out.print("Enter phrase: ");
            String phrase = keyboard.nextLine();
            System.out.print("Enter a substring to search after: ");
            String substring = keyboard.next();
            int index;
            if (phrase.length() > substring.length()) {
                index = phrase.indexOf(substring);
                if (index != -1 && index < phrase.length() - substring.length()) {
                    System.out.println(phrase.charAt(index + substring.length()));
                }
                if (index == phrase.length() - substring.length()) {
                    System.out.println("'" + substring + "' is the last substring in '" + phrase + "'");
                }
                if (index == -1) {
                    System.out.print("'" + substring + "' is not in '" + phrase + "'");
                }
            }
        }
    }
}

另一个示例运行：

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: do
w

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: down
'down' is the last substring in 'upside down'

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: x
'x' is not in 'upside down'

另一个示例运行：

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: do
w

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: down
'down' is the last substring in 'upside down'

Enter option: 3
Enter phrase: upside down
Enter a substring to search after: x
'x' is not in 'upside down'

---

似乎你问了两次同样的问题。似乎你问了两次同样的问题。当我输入“颠倒”和“做”时，它应该输出“w”，但它输出“e”

do

不是一个字母。如果要搜索字母或单词，则需要更改程序。你想让我帮你做吗？是的，你能帮我吗？我已经更新了答案。对不起，我不能使用子字符串，它必须与for循环或其他任何不是java内置方法的东西一起使用。再次抱歉，当我输入“倒置”和“do”时，它应该输出“w”，但它输出“e”

do

不是字母。如果要搜索字母或单词，则需要更改程序。你想让我帮你做吗？是的，你能帮我吗？我已经更新了答案。对不起，我不能使用子字符串，它必须与for循环或其他任何不是java内置方法的东西一起使用。再次抱歉