Question

帮忙看个java小程序哪儿错了解决方案

Answer 1

package com.java.lang;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class NatualNumber{
public static void main(String[] args) {
if (args.length == 0) {
System.out.println("请输入一个数字");
} else {
if (isDigit(args[0])) {
if("0".equals(args[0])) {
System.out.println("请输入自然数。");
} else {
System.out.println("您输入的数字[ "+ args[0] +" ]是自然数。");
}
} else {
System.out.println("请输入自然数。");
}
}
}

public static boolean isDigit(String string) {
boolean flag = false;
Pattern p = Pattern.compile("^\\d$");
Matcher m = p.matcher(string);
flag = m.matches();

return flag;
}
}