Transform all elements of a list of strings to upper case

Question

I want to transform a list of strings to upper case.

Here's my code to do this:

List<String> list = Arrays.asList("abc", "def", "ghi");
List<String> upped = list.stream().map(String::toUpperCase).collect(Collectors.toList());

Is there a simpler/better way to do this?

There's always another way. Like a for loop. What sort of answer are you looking for? — Tunaki, Feb 14 '16 at 18:16
Note that a better way would be not to rely on `toUpperCase` but use `toUpperCase(locale)`. — Tunaki, Feb 14 '16 at 18:27

Bohemian · Accepted Answer · 2016-02-14T18:27:30.153

67

You have not actually transformed the list; you have created a new list.

To transform the list in one small method call, use List#replaceAll():

list.replaceAll(String::toUpperCase);

edited Feb 14 '16 at 18:27

answered Feb 14 '16 at 18:18

Bohemian

Does this actually assign the transformed Strings to their respectful positions in the list? I only ask because I'm used to the string format `s=s.replaceAll()` but I'm not familiar with this implementation for List. Sounds like good info :) – Calvin P. Feb 14 '16 at 18:24
2

@CalvinP.yes - it performs an in-place conversion on each element using the provided lambda, so element order is preserved. – Bohemian Feb 14 '16 at 18:26

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