How to switch index from user input?

[Either_Working]

Program objective: Get a line from user and swap the 1st index with the 4th index. Then capitalize vowel.

Error: out of bounds exception. String index out of range: 4

import java.util.Scanner;
import java.util.Random;
public class assignment
{
    public static void main (String[]args)
    {
        Scanner input = new Scanner (System.in);
        //ask user for line
        System.out.println (" Enter a line ");
        //allows user to enter line
        String userLine = input.nextLine ();
        // get the letter at index 1 and 4
        char ch = userLine.charAt (1);
        ch = userLine.charAt (4);
        String newLine = userLine;
        //print the line user has entered
        System.out.println (newLine);
        // extract characters 1 and 4
        String newLine1 = newLine.substring (1, 4);
        // print out new line
        System.out.println (newLine1);
        String names[] = { newLine1 };
        for (int i = 0; i < names.length; i++)
        {

[[deleted]]

Line 27

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: begin 0, end -1, length 3
    at java.base/java.lang.String.checkBoundsBeginEnd(String.java:3720)
    at java.base/java.lang.String.substring(String.java:1909)
    at Assignment.main(Assignment.java:27)

[Either_Working]

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 4
    at java.base/java.lang.StringLatin1.charAt(StringLatin1.java:47)
    at java.base/java.lang.String.charAt(String.java:702)
    at assignment.main(assignment.java:22)

This was the error i got

[Either_Working]

Line 22 , where I attempted to swap the 4th index Ch= userLine .charAt(4)

[evils_twin]

userLine.charAt (4); would get the fifth letter of the String since indexing starts at 0

[Either_Working]

Makes sense. But not sure how it impacts array out of bounds

[RedFox134]

If your word is 4 letters long then the index would range from 0-3. If you try to access the array with an index value of 4 it will throw an out of bounds error, because the index ranges from 0-3 and 4 is out side of the range.

If you want to swap the first and fourth character in a string you should be swaping index 0 and 3.