java string replace all

Question

I have a two dimensional array that contains pairs of strings. If one string is found it should replace it with its pair.

The code:

 for (int i = 0; i < pairs.length; i++) {
 if (name.contains(pairs[i][0])) {
 name.replaceAll(pairs[i][0], abbr[i][1]);
 }
 }

It is not replacing the strings. What is the error?

• kosa: Some sample input & expected output may help. As well as "review" it is case for replace() (or) replaceAll()? and last but not least, Strings are immutable.
• CosmicGiant: Replace abbr[i][1] with pairs[i][1]...Also, use a Map<String,String> instead of bidimentional array...
• 11684: I don't really get the question... Could you post the contents of the array BEFORE you run your code, and the desired contents of the array AFTER you run your code?

Answer 1

You are neglecting to assign the result of replaceAll, and so the modification is lost.

Perhaps you want to keep the modified string as name:

for (int i = 0; i < pairs.length; i++) {
 if (name.contains(pairs[i][0])) {
 name = name.replaceAll(pairs[i][0], abbr[i][1]);
 }
}

Note that java String objects are immutable, so calling name.replaceAll doesn't modify name, it returns a new String with the modifications.

Answer 2

String is immutable.

name.replaceAll(pairs[i][0], abbr[i][1]);

creates a new String (it doesn't modify the "name" String)

Try

name = name.replaceAll(pairs[i][0], abbr[i][1]);

Answer 3

A modified version of the string is being created, however it's return value is being lost.

name = name.replaceAll(pairs[i][0], abbr[i][1]);

should work.

• RNJ: I don't think the string is being modified. A new one is created with the modification and being passed back.
• SamuelDavis: Thank you. I didn't realize I had written it that way! Edited my answer.