Extracting Digits from Strings in Java

When working with strings in Java, there may arise a need to extract only the numerical digits. This operation can be achieved using various approaches, including regular expressions.

Regular Expressions

One efficient method is to utilize the replaceAll method with a regular expression that matches non-digits (\\D ) and replaces them with an empty string. For instance:

String str = "123-456-789";
str = str.replaceAll("\\D ",""); // Result: "123456789"

This approach effectively removes all characters except for digits from the string, resulting in the desired output.

Additional Libraries

The replaceAll method is part of the Java String class and does not require the installation of any additional libraries. It is a built-in feature of the Java programming language.

Conclusion

Extracting digits from strings in Java can be conveniently accomplished using regular expressions, which provide a powerful tool for manipulating and parsing text data. The replaceAll method, coupled with the appropriate regular expression, enables efficient digit extraction without the need for additional libraries.