Java如何使用正则表达式从字符串中提取数字

    public static void main(String[] args) {
        String content = "111adj222adf33-f44444";
        Pattern pattern = compile("\\d+"); // java.util.regex.Pattern.compile
        Matcher matcher = pattern.matcher(content);
        while (matcher.find()) {
            System.out.println(matcher.group(0));
        }
        /**
         * 结果：
         * 111
         * 222
         * 33
         * 44444
         */
    }

import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class ExtractNumbersFromString {
 
    public static void main(String[] args) {
    
        String str = "有12只猫和13只狗。";
        Pattern pattern = Pattern.compile("\\d+");
        Matcher matcher = pattern.matcher(str);
        while (matcher.find()) {
            System.out.println(matcher.group());
        }
    }
}

public class ExtractNumbersFromString {
 
    public static void main(String[] args) {
    
        String str = "有12只猫和13只狗。";
        StringBuilder sb = new StringBuilder();
        for (char c : str.toCharArray()) {
            if (Character.isDigit(c)) {
                sb.append(c);
            }
        }
        System.out.println(sb.toString());
    }
}