Quick Vim Tip: Change Text Between White Space

private List<String> strings;

When the cursor is on the S of String, use ciW to delete List<String> and start insert. Obviously, you can use any other command with that movement, for example yank the text (yiW) or delete it (diW).

From :help WORD:

A WORD consists of a sequence of non-blank characters, separated with white space. An empty line is also considered to be a WORD.