Regular expression for not empty

Question

I need a Java regular expression, which checks that the given String is not Empty. However the expression should ingnore if the user has accidentally given whitespace in the

Answer 1

It's faster to create a method for this rather than using regular expression

/**
 * This method takes String as parameter
 * and checks if it is null or empty.
 * 
 * @param value - The value that will get checked. 
 * Returns the value of "".equals(value). 
 * This is also trimmed, so that "     " returns true
 * @return - true if object is null or empty
 */
public static boolean empty(String value) {
    if(value == null)
        return true;

    return "".equals(value.trim());
}

Answer 2

This should work:

/^\s*\S.*$/

but a regular expression might not be the best solution depending on what else you have in mind.

Answer 3

^\s*\S

(skip any whitespace at the start, then match something that's not whitespace)

Answer 4

For a non empty String use .+.

Answer 5

For testing on non-empty input I use:

private static final String REGEX_NON_EMPTY = ".*\\S.*"; 
// any number of whatever character followed by 1 or more non-whitespace chars, followed by any number of whatever character 

Answer 6

You don't need a regexp for this. This works, is clearer and faster:

if(myString.trim().length() > 0)