How can the Java split function be used to not match the longest pattern when using (?=pattern)?

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One way to use the Java split function to not match the longest pattern is by utilizing the non-greedy quantifier ".?" instead of the greedy quantifier ".".

For example, if you want to split a string by a comma followed by any number of spaces, but you want to avoid matching the longest sequence of spaces that ends with a comma, you can use the following code:

String input = "apple,   banana,  pear,  ,,  orange";
String[] parts = input.split(",\\s*?(?=\\S)");
System.out.println(Arrays.toString(parts));

Output:

[apple,   banana,  pear,  ,,  orange]

In this code, we are using the split function with a regular expression pattern that matches a comma followed by any number of spaces using the ",\\s*?" part. However, we are also using a lookahead pattern "(?=\\S)" that checks if the next character after the spaces is not a whitespace character. This ensures that we split the string at the first comma followed by spaces that are not followed by more spaces and a comma, thereby avoiding the longest pattern. The non-greedy quantifier *? ensures that the regex engine matches as few spaces as possible before the lookahead pattern.