Replacing a "char" in StringBuilder string

Question

My requirement is pretty simple, fetch a char location and replace it with another.
Only catch is that, the char and its index comes at run time and can not be hard-coded.

Dummy code of my actual implementation :

public static void main(String args[])
{
   StringBuilder sb = new StringBuilder("just going nuts")  ;
   System.out.println(" "+sb);
   //System.out.println(sb.charAt(4)); //this works
   sb.setCharAt(sb.indexOf((sb.charAt(4))), sb.charAt(0)); //line 8 -error line
   System.out.println(" "+sb);
}

I even tried enclosing char in quotes :

sb.setCharAt(sb.indexOf(( "\""+sb.charAt(4)+"\"" )), sb.charAt(0));

but still same error

Error

line no:8: cannot find symbol
symbol : method indexOf(char)
location: class java.lang.StringBuilder
sb.setCharAt(sb.indexOf((sb.charAt(4))), sb.charAt(0));

I am not very fluent in Java but couldn't find setCharAt function examples having dynamic values like in this case!!

Off topic suggestion: System.out.println(" "+sb); could be System.out.println(sb.toString()); — Totò
– Totò, Commented May 7, 2014 at 7:13
@Totò : thanks mate but i can not use it as the output is further processed!! :) — NoobEditor
– NoobEditor, Commented May 7, 2014 at 7:17
If you already know the index of the character you want to replace, why not use sb.setCharAt(4, sb.charAt(0)) ? — Stefan
– Stefan, Commented May 7, 2014 at 7:19

dimitrisli · Accepted Answer · 2014-05-07 07:19:12Z

6

The error is because indexOf is expecting a String not a char so all you have to do is wrap it with String.valueOf

sb.setCharAt(sb.indexOf(String.valueOf((sb.charAt(4)))), sb.charAt(0));

outputs

 just going nuts
 justjgoing nuts

Modern IDEs should catch this compile time error while you type even offer the solution (in the case below IntelliJ):

enter image description here

answered May 7, 2014 at 7:19

dimitrisli

21.4k12 gold badges64 silver badges65 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

NoobEditor Over a year ago

@dimitrisli : is there a way around without using String wrapper?

Scary Wombat Over a year ago

@NoobEditor if you are just using ascii, then cast as an int should work too.

NoobEditor · Accepted Answer · 2019-09-09 07:09:46Z

0

Try to Add null string

sb.setCharAt(sb.indexOf((sb.charAt(4))+""), sb.charAt(0));

As sb.indexOf() works with string not chatacters.

edited Sep 9, 2019 at 7:09

NoobEditor

16k20 gold badges85 silver badges117 bronze badges

answered Sep 9, 2019 at 5:28

xixo

1

Collectives™ on Stack Overflow

Replacing a "char" in StringBuilder string

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related