Help With Input.charAt(LastIndex);

[susan]

I have got a question about something that I just cant figure out on my own.
With that said, here is the code:

Code:

import java.util.*;
import javax.swing.*;
import java.lang.*;
public class Prob01BAC {
  public static void main(String args[]){
    String Input, LastChar; 
    int LastIndex; 
    double StringLength; 
    
    //Gathers Input from user and stores in the 'Input' Variable for later use
    Input = JOptionPane.showInputDialog("Please enter a sentence");
    
    StringLength = Input.length();
    LastIndex = Input.lastIndexOf(Input);
    LastChar = Input.charAt(LastIndex);
  
    //Check to see if the last character of the string is a '?'
    if ( LastChar == "?" ){
      //Checks to see if the string is even or odd by dividing by 2 and checking the remainder
      //0 = even, anything else is odd
      if ( StringLength % 2 == 0 ){
        JOptionPane.showMessageDialog(null, "Yes");
      }
      else{
        JOptionPane.showMessageDialog(null, "No");
      }
    }
    //Checks to see if the last character of the string is a '!'
    else if ( LastChar == "!" ){
      JOptionPane.showMessageDialog(null, "Wow");
    }
    //This is a sort of catch all for anything that doesnt meet the above requirements
    else{
      JOptionPane.showMessageDialog(null, "You always say \"" + Input + "\"");
    }   
  }
}

When i try and compile it I get this message

Code:

Prob01BAC.java:20: incompatible types
Found : char
Required : java.lang.String
LastChar = Input.charAt(LastIndex);

the first ( has a marker under it).

The object of the program is to take a user input string using the JOptionPane method and then responding with a certain string according to certain variables like the string length being odd or even, the string ending in a ! or a ?, or nothing at all.

I have tried googling the error, but with my limited knowledge I found nothing that appeared to be of any use in the way of resloving the problem.

[cachi]

The problem is that you are trying to assign a char type to a String type and this is not allowed since these types are incompatible.

You declared LastChar as a String but in your code you do this:

Code:

LastChar = Input.charAt(LastIndex);

As the String.charAt method returns a char, the things go wrong.

Some info about String and char:
- char is a primitive type and represents a single character: 'a', 'D'. Notice that you always use single quotes (') to represent a char literal.

- String is an object which represents a string of characters: "abcd". Notice that you always use double quotes (") to represent a String literal.

So the solution for your problem is to change the LastChar type to char:

Code:

 char LastChar;

Furthermore you need to change the lines:

Code:

if ( LastChar == "?" ){

and

Code:

if ( LastChar == "?" ){

To:

Code:

if ( LastChar == '?' ){

and

Code:

if ( LastChar == '?' ){

Pay attention to the single quotes. If you say:

Code:

(LastChar == "?")

The java compiler will interpret "?" as a String with only one character and not as a char.
Greetings.