IP判断（JAVA语言）

具体代码如下：

import java.util.Scanner;

public class ContestUsing {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a;
        boolean isTrue = true;
        while (scanner.hasNext()) {
            String str = scanner.nextLine();
            String subString[] = str.split("\\.");//split("分隔符")用于分隔函数，因为"."为转义符，所以要加//
            if(subString.length!=4) {
                System.out.println("N");
                continue;
            }
            for (int i =0;i<4;i++)
            {
                if (subString[i].toCharArray().length>1
                &&subString[i].charAt(0)=='0') {  
                    isTrue = false;
                    break;
                }
                try {
                     a = Integer.valueOf(subString[i]);
                }
                catch (Exception e) {
                    isTrue = false;
                    break;
                }
                if(a<0||a>255)
                {
                    isTrue = false;
                    break;
                }
            }
            if (isTrue)
                System.out.println("Y");
            else
                System.out.println("N");
            isTrue = true;

        }
    }
}