测试空白空间时引发异常

Question

I am stumped on this problem, I am trying to output the initials of first name and last name. I am testing for last names that have an "Mc"/ "Mac" / "O'Connell" and "O Connell" but the space is producing an error of type ---

full stack trace is:

run:
Please enter First name :colm
Please enter Last name o connell
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 1
    at java.lang.String.charAt(String.java:646)
    at Initials2.InitialsOutput(Initials2.java:22)
    at Initials2.main(Initials2.java:51)
Java Result: 1
BUILD SUCCESSFUL (total time: 13 seconds)

here is the code that throws an exception:

import java.util.Scanner;


public class InitialsTest {

    public static void InitialsOutput(String firstName, String lastName){

    // character array to hold the initials ex hellen walsh - output HW
        char charInitials[] = new char[5]; 
        charInitials[0] = firstName.charAt(0);

        // test for different name types to output initials
        // testing for mcMahon (which works)
        // testing for o'donnell (which works)
        // testing for macDonagh (which works)
        // testing for O Connell (which fails - throws exception)
        // the first test is for  a blank space (which fails) or an ' (which works)
        if (lastName.codePointAt(1) == '\u0020' | lastName.codePointAt(1) == 39){
        //if (lastName.codePointAt(1) == 32 | lastName.codePointAt(1) == 39){
        //if (lastName.codePointAt(1) == 0020 | lastName.codePointAt(1) == 39){
        //if (lastName.charAt(1) == ' ' | lastName.codePointAt(1) == 39){

            charInitials[1] = lastName.charAt(0);
            charInitials[2] = lastName.charAt(2); 
        } else if ((lastName.charAt(0) == 'm' | lastName.charAt(0) == 'M') 
                    & (lastName.charAt(1) == 'c' | lastName.charAt(1)== 'C')){
            charInitials[1] = lastName.charAt(0);
            charInitials[2] = lastName.charAt(2);
        } else if ((lastName.charAt(0) == 'm' | lastName.charAt(0) == 'M')
                    & (lastName.charAt(1) == 'a' | lastName.charAt(1)== 'A')
                    & (lastName.charAt(2) == 'c' | lastName.charAt(2)== 'C')){
            charInitials[1] = lastName.charAt(0);
            charInitials[2] = lastName.charAt(3);
        }
        else {
            charInitials[1] = lastName.charAt(0);
        }
       String initials;
       initials = new String (charInitials);

        System.out.println("Initials are : " + initials.toUpperCase());
    }


    public static void main(String[] args) {
            Scanner userInput = new Scanner(System.in);
            System.out.print("Please enter First name :");
            String first = userInput.next();
            System.out.print("Please enter Last name ");
            String last = userInput.next(); 
            InitialsOutput(first, last);                  
    }

}

Answer 1

It's because you're using Scanner.next() which breaks your last name into 2 tokens: o and connell . The method InitialsOutput is called with firstName = colm and lastName = o . That's why lastName.codePointAt(1) gives you the error.

Changing userInput.next(); to userInput.nextLine(); should do the trick.