How Can I Extract Numbers from a String Using Java Regular Expressions?

Extracting Numbers from Strings Using Regular Expressions

To extract numbers from a string into an array of integers using regular expressions, you can utilize the Pattern and Matcher classes in Java. Here's a solution:

Solution:

Pattern p = Pattern.compile("-?\d+");
Matcher m = p.matcher("There are more than -2 and less than 12 numbers here");
LinkedList<Integer> numbers = new LinkedList<>();

while (m.find()) {
   numbers.add(Integer.parseInt(m.group()));
}

System.out.println(numbers); // prints [-2, 12]

Explanation:

• p = Pattern.compile("-?\d "): This line compiles a regular expression pattern that matches any number, which can optionally have a leading negative sign.
• m = p.matcher("..."): This line creates a Matcher object using the pattern and the specified string.
• The while loop iterates over all matches found by the Matcher.
• numbers.add(Integer.parseInt(m.group())): For each match, the numeric value is extracted using m.group() and then parsed into an integer using Integer.parseInt().
• The result is a LinkedList of integers containing the extracted numbers.

Note that the -? part in the pattern handles negative numbers. If you don't want to allow negative numbers, you can remove it from the pattern.

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