How to trim whitespace from a string

Short answer

The strip() method removes spaces, tabs and line breaks from both ends:

void main() {
    String input = "  Anna \n";
    IO.println("[" + input.strip() + "]");
}

Output:

[Anna]

Only one side

stripLeading() removes whitespace at the start, stripTrailing() at the end:

void main() {
    String text = "   hi   ";
 
    IO.println("[" + text.stripLeading() + "]");
    IO.println("[" + text.stripTrailing() + "]");
}

Output:

[hi   ]
[   hi]

strip or trim

The older trim() removes only characters with codes up to 32 and does not know about Unicode spaces, such as a non-breaking space from Word or HTML. strip() does:

void main() {
    String text = " price ";
 
    IO.println("[" + text.trim() + "]");
    IO.println("[" + text.strip() + "]");
}

Output:

[ price ]
[price]

Spaces inside the string

Collapse extra spaces between words with a regular expression:

void main() {
    String text = "  too    many   spaces ";
    IO.println(text.strip().replaceAll("\\s+", " "));
}

Output:

too many spaces

Common mistake

Calling strip() without keeping the result. The method does not change the string, it returns a new one:

void main() {
    String name = "  Oleg  ";
    name.strip();
    IO.println("[" + name + "]");
}

Output:

[  Oleg  ]

Thanks for reading!

Short answer

Only one side

strip or trim

Spaces inside the string

Common mistake

Functions used in this recipe

Thanks for reading!