Thread: Converting letter casing in strings

I am trying to figure out how to alter specific characters in a string. Say I were to enter a string in that contains a lowercase "i".
How could I command java to convert the lowercase "i" to an uppercase "I" before printing the string?

I will give it a look when I get to a computer thanks!! if anyone else has any feedback or the answer to my question I would appreciate it if they'd chime in. Other resources like the API would be appreciated too.

You're close, but I am aware of the toUpperCase method. I'm trying to convert a specific character though; not an entire string of characters. If I were to enter the word "laugh" I would want it to alter it to say "Laugh" with a capitalized L, and if a capitalized "L" was entered in the first place for it to do nothing.

I have tried to use lines like the ones I'll put down below, but I have not found anything that is working... I realize both lines won't work if they're both inside the if statement. I included both to give examples of what I have been trying incase there was any confusion. I am sure I'm missing something, but I can't figure out what it is exactly...

String input = "laugh";

for(int i = 0; i < input.length(); i++){

if(input.charAt(i) =='l'){

input.replace('l' , 'L');
//did not work

input.charAt(i) = 'L';
//did not work either

continue;

}//end if

}end for loop

Originally Posted by kenster421

I think what you are asking for is impossible. In Java, strings are immutable, i.e., you cannot access the array of characters and edit them. You must create a new String and reflect the changes you want in that new instance and then assign it to the proper reference.

What methods would I have to use in order to accomplish this?

If this is not possible why is there a replace method for characters? Just wondering, because the examples I've seen of it lead me to believe what I'm doing is much easier then it seems.

Would converting the string into a character array and then making the changes be the best course of action, and then converting it back to a string if that too is possible?

Originally Posted by KevinWorkman

The toUpperCase() methods are really the only thing you need.



It is possible, and even quite simple. What Kenneth was saying is that String are immutable- that means you can't change the original String. But you can certainly store the result in a new String. For example, to take a substring, I can't do this:

String someString = "this is an example String";
someString.substring(2, 5);
//someString is still "this is an example String"

Instead, I have to do this:

String someString = "this is an example String";
String otherString = someString.substring(2, 5);
//someString is still "this is an example String"
//otherString contains the substring

That's how all the String methods work, including replace and toUpperCase.




I don't think so.

How could i use the toUpperCase method to accomplish this?

As for using subStrings would I have to use two incase I were to enter a word where the 'L' might be inside of the given word like if I were to enter the words "world" or "floor" for example to have them displayed as "worLd" and "fLoor".

String input = "little";

for(int i = 0; i < input.length(); i++){

else if(input.charAt(i) == 'l'){

output = input.replace('l', 'L');

}//end l to L conversion

}//end for loop

figured it out. the output is changed from "little" to "LittLe".