How Can I Extract Digits from a String in Java While Handling Non-Digit Characters?

Extracting Digits from a String: Handling Non-Digit Characters

In Java, extracting digits from a string can be achieved using regular expressions. However, this approach requires careful handling of non-digit characters to preserve the integrity of the extracted digits.

Utilizing Regular Expressions

To extract digits, developers can utilize the replaceAll method along with a regular expression pattern. This pattern, ("\D ?"), matches non-digit characters denoted by D and quantifies them as greedy ( ) or reluctant (?).

Example

Consider the example given: "123-456-789." Our goal is to obtain "123456789."

<code class="java">String str = "123-456-789";
str = str.replaceAll("\D+", "");
System.out.println(str); // Output: 123456789</code>

Explanation

The replaceAll method replaces all substrings that match the specified pattern with an empty string. In this case, the pattern ("\D ?") matches substrings containing non-digit characters. By replacing them with an empty string, only the digits remain.

Additional Libraries

The solution provided above does not require any additional libraries to be installed. It utilizes standard Java classes and methods for string manipulation and regular expressions.

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