Extract Numbers from String in Java: 2 Methods

In Java, you can use regular expressions or loop through strings to extract numbers.

1. Design or arrangement
2. One who matches

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        String str = "abc123def456";
        Pattern pattern = Pattern.compile("\\d+");
        Matcher matcher = pattern.matcher(str);
        
        while (matcher.find()) {
            String number = matcher.group();
            System.out.println(number);
        }
    }
}

1. Check if the character is a digit.

public class Main {
    public static void main(String[] args) {
        String str = "abc123def456";
        StringBuilder sb = new StringBuilder();
        
        for (char c : str.toCharArray()) {
            if (Character.isDigit(c)) {
                sb.append(c);
            }
        }
        
        String numbers = sb.toString();
        System.out.println(numbers);
    }
}

The choice between these two methods for extracting numbers from a string depends on the specific requirements and format of the string.