How to use the scanner class to ask for a character?

Question

Hey guys, this is my assignment:
Ask the user for a single letter and a sentence, and print out the
number of times that letter shows up in the sentence.
Please tell me how to scan for a character. I tried this:
import java.util.Scanner;
public class Frequencies
    public static final void main(String[] args)
        Scanner scanner = new Scanner(System.in);
        Scanner scan = new Scanner(System.in);
        System.out.println("Enter a sentence");
        String x = scanner.next();
        System.out.println("Enter a letter to look for");
        String y = scan.next();
        char z = y.charAt(0);
        int chara = 0;
        for(int i = 0; i<x.length(); i++){
                if(z==y.charAt(i)){
                        chara = chara++;
        System.out.println("There are " + chara + " " + z + "s in the sentence");
}and got the error after Running (not compiling):
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 1
        at java.lang.String.charAt(String.java:687)
        at Frequencies.main(Frequencies.java:16)I thought this meant that I was asking for the character in postition 1 of string y, but in my code I wrote position 0
when I tried inserting words in the character place (just to see what happened, not expecting functionallity, I got
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: [NUMBER OF CHARACTERS]
        at java.lang.String.charAt(String.java:687)
        at Frequencies.main(Frequencies.java:16)Please help.
The assignment isn't due nor graded, this is just killing me lol.
Thanks in advance
Edited by: Sevan on Oct 18, 2008 4:40 PM

Answer 1

jverd wrote:
Skydev2u wrote:
I've used this method for a while now and it gets the job done.
import java.util.Scanner;
public class ReadInput {
public static void main(String[] args) {
Scanner UserInput = new Scanner(System.in);
char letter = UserInput.findWithinHorizon(".", 0).charAt(0);
I know you're trying to help, but this isn't really doing it. It does nothing to address the source of the OP's problem. The way he's doing it now is almost right. He just needs to do a tiny bit of detective work to fix a small bug. Tossing off a totally different approach, with no explanation, is not particularly helpful.Your right jverd I skimmed the OP's problem too quick;y and in tern didn't understand it fully. After reading the post thoroughly I saw that the problem can be solved by taking the sentence the user enters and then converting it into a array of characters. Then searching for the specific letter the user enters is achieved by comparing it to each individual element of the char array. Then incrementing a counter variable each time a match is made. I hope this example code solve your problem.
* @author skydev
import java.util.Scanner;
public class SentenceReader {
    public static void main(String[] args) {
        int counter = 0; //Amount of time the letter appears in the sentence
        char letter;    //Letter the user search for
        char[] sentenceArray; //char array to hold the elements of the string the user inputs
        String sentence; //sentence the user inputs
        Scanner UserInput = new Scanner(System.in);
        System.out.println("Please enter a sentence! ");
        sentence = UserInput.nextLine();
        sentenceArray = sentence.toCharArray(); //splits up the users sentence into a array of char
        System.out.println("Please enter a letter to search for ");
        letter = UserInput.findWithinHorizon(".", 0).charAt(0);
         for(int i = 0; i < sentence.length(); i++){
                if(letter == sentenceArray){ //search to see if the letter of interest equals to each char (letter) of the array
counter++; //increments the amount of time the letter appears, set to 0 by default
System.out.println("The letter appeared " + counter + " times in the sentence"); //Displays the result :) I love programming