Finding all uppercase letters of a string in java

Question

So I'm trying to find all the uppercase letters in a string put in by the user but I keep getting this runtime error:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: 
String index out of range: 4
at java.lang.String.charAt(String.java:686)
at P43.main(P43.java:13)

I feel foolish but I just can't figure this out and oracle even talks about charAt on the page about java.lang.StringIndexOutOfBoundsException

Here is my code for finding the uppercase letters and printing them:

import java.io.*;
import java.util.*;

public class P43{
   public static void main(String[] args){
      Scanner in = new Scanner(System.in);
      //Uppercase
      String isUp = "";
      System.out.print("Please give a string: ");
      String x = in.next();
      int z = x.length();
      for(int y = 0; y <= z; y++){
         if(Character.isUpperCase(x.charAt(y))){
            char w = x.charAt(y);
            isUp = isUp + w + " ";
         }
      }
      System.out.println("The uppercase characters are " + isUp);
      //Uppercase
   }
}

I'd really appreciate any input and or help.

Answer 1

for(int y = 0; y <= z; y++){

should be

for(int y = 0; y < z; y++){

Remember array index starts from ZERO.

String length returns

the number of 16-bit Unicode characters in the string

Because loop started from ZERO, loop should terminate at length-1.