This program gives either an error, or does not give the last letter, how should I fix it?-CodePudding

import java.util.Scanner;

class Assignment4 
{
  public static void main(String[] args) 
  {
        
    Scanner scan = new Scanner(System.in);
    System.out.println("Type the message to be shortened");
    String msg = scan.nextLine();
    msg = msg.toLowerCase();
    String alg1 = "";
    int vowelC = 0;
    int repeatC = 0;
    System.out.println("Algorithm 1");
    for (int i = 0; i<msg.length();i  ){
      if(msg.substring(i-1,i).equals(" ")){
        alg1 =msg.substring(i,i 1);
      }
      else{
        if (msg.substring(i,i 1).equals("a") || msg.substring(i,i 1).equals("e") || msg.substring(i,i 1).equals("i") || msg.substring(i,i 1).equals("o") || msg.substring(i,i 1).equals("i")){
            vowelC  ;
        }
        else if (msg.substring(i,i 1).equals(msg.substring(i-1,i))){
          repeatC  ;
      }
        else{
        alg1 =msg.substring(i,i 1);
        }
      }
    }
    System.out.print(alg1);
    
  }
}

This results in a index out of range, -1. I understand why this is,that is not the issue, but when I tweak it by having the control of the for loop be i<msg.length()-1, it works but does not print the last letter. I also tried changing i to start at 1, but that cut off the first letter. Just not sure how to get the whole message with no error. Thanks!

CodePudding user response：

What is the program trying to achieve?

Your for loop is correct, you should have i = 0; i < length; i

Saying length-1 will stop one character short, as you noticed. For the substring calls, when you are using i-1 and ì 1 to refer to parts of the string, you should use if statements to check for the edge cases, when i=0 and when i=length, because both of those will result in out of range (e.g. results in attempts at accessing string[-1] and string[length], either of which don't exist).

Or put the substring logic inside a try...catch and carry on through the out of range exception when err instanceOf OutOfRangeException

CodePudding user response：

Hard to decipher what the output should be, try iterating through each of the characters...:

import java.util.Scanner;

public class LastMain {

    public static void main(String[] args) {

        Scanner scan = new Scanner(System.in);
        System.out.println("Type the message to be shortened");
        String msg = scan.nextLine();
        msg = msg.toLowerCase();
        String alg1 = "";
        int vowelC = 0;
        int repeatC = 0;

        System.out.println("Algorithm 1");

        char lastChar = '\n';

        for (int i = 0; i<msg.length();i  ){
            char thisChar = msg.charAt(i);

            switch (thisChar) {
            case 'a':
            case 'e':
            case 'i':
            case 'o':
            case 'u':
                vowelC  ;
                break;
            default:
                if(thisChar != lastChar) {
                    alg1  = thisChar;
                } else {
                    repeatC  ;
                }
                break;
            }

            lastChar = thisChar;
        }

        System.out.println(alg1);

        System.out.println("Number of vowels: "   vowelC);
        System.out.println("Number of repeats: "   repeatC);
    }
}

Giving the output of

Type the message to be shortened
This is the message to be shortened
Algorithm 1
ths s th msg t b shrtnd
Number of vowels: 11
Number of repeats: 1

CodePudding user response：

I apologize, what this is trying to achieve is to shorten a message by removing all vowels, other than those that start a word, and any letters that repeat. I should have added this.