Using a For Loop to set all lower case to uppercase

Question

How do you use a for loop to set all the lower cases of a string into upper cases?

This is what I did, but I get two compiler errors,

The method setCharAt(int, char) is undefined for the type java.lang.String [line 7]

Array cannot be resolved [line 12]

public static String allUpperCases(String toEncode){
    int length = toEncode.length();

    for (int i = 0; i < length; i++){
      char ch = toEncode.charAt(i);
      if (Character.isLowerCase(ch)){
        toEncode.setCharAt(i, Character.toUpperCase(ch));
      }
    }

    return toEncode;
  }

See http://stackoverflow.com/questions/4576513/str-setcharatindex-x — NPE, Oct 27 '15 at 22:06
What part of the error message, "The method setCharAt(int, char) is undefined for the type java.lang.String[line 7]", is confusing? It describes exactly what you did wrong, and it states what line the mistake is on. We need to know what part you don't understand in order to write a helpful answer. Otherwise, we are just going to repeat what the error says in different words. — Rainbolt, Oct 27 '15 at 22:23

score 2 · Accepted Answer · answered Jun 21 '16 at 07:56

2

You can just use a single operation!

my_string = my_string.toUpperCase();

answered Jun 21 '16 at 07:56

Michael Meneghini

76
7

wadda_wadda · Answer 2 · 2015-10-27T22:19:59.700

You don't need to use a for loop to set a string to lower or upper case. You can use myString = myString.toLowerCase();. Conversely, there is the opposite: myString = myString.toUpperCase();. You should really read the String API.

With regards to your errors:

The String type does not have a setCharAt() function in Java. That's because a String, at least in Java, is an immutable type. When you "change" a string, unless you're using a StringBuilder or modifying the underlying char array, you are actually assigning a new String to the variable.

I can't diagnose your Array cannot be resolved error, as I don't see an array in your code.

score 1 · Answer 3 · answered Oct 27 '15 at 22:08

1

If you just want your String all uppercase, there is a function in Java:

yourstring.toUpperCase();

answered Oct 27 '15 at 22:08

z3ntu

190
7
20

Using a For Loop to set all lower case to uppercase

3 Answers3