正規表現を使用して文字列から数値を抽出するにはどうすればよいですか？

次の正規表現のいずれかを使用して、指定された文字列の数値を照合できます-

“\\d+”
Or,
"([0-9]+)"

例1

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class ExtractingDigits {
   public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter sample text: ");
      String data = sc.nextLine();
      //Regular expression to match digits in a string
      String regex = "\\d+";
      //Creating a pattern object
      Pattern pattern = Pattern.compile(regex);
      //Creating a Matcher object
      Matcher matcher = pattern.matcher(data);
      System.out.println("Digits in the given string are: ");
      while(matcher.find()) {
         System.out.print(matcher.group()+" ");
      }
   }
}

出力

Enter sample text:
this is a sample 23 text 46 with 11223 numbers in it
Digits in the given string are:
23 46 11223

例2

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Just {
   public static void main(String[] args) {
      String data = "abc12def334hjdsk7438dbds3y388";
      //Regular expression to digits
      String regex = "([0-9]+)";
      //Creating a pattern object
      Pattern pattern = Pattern.compile(regex);
      //Creating a Matcher object
      Matcher matcher = pattern.matcher(data);
      System.out.println("Digits in the given string are: ");
      while(matcher.find()) {
         System.out.print(matcher.group()+" ");
      }
   }
}

出力

Digits in the given string are:
12 334 7438 3 388