判断字符窜不是数字 Java

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

public class isNumeric {

	public boolean isNumeric(String str) {
		Pattern pattern = Pattern.compile("[0-9]*");
		Matcher isNum = pattern.matcher(str);
		if (!isNum.matches()) {
			return false;
		}
		return true;
	}

	public static void main(String[] args) {
		//int a = 10;
		isNumeric m = new isNumeric();
		System.out.println(m.isNumeric("1213ss23"));
	}
}