java if 条件语句

import java.util.Scanner;

public class Sample {

    public static void main(String[] args) {
        int num;
        Scanner ip = new Scanner(System.in);
        System.out.print("Enter any number: ");
        num = ip.nextInt();
        if (num > ) {
            System.out.println("Positive number");
        }
        if (num < ) {
            System.out.println("Negative number");
        }
        if (num == ) {
            System.out.println("Zero");
        }
        ip.close();
    }
}

OUTPUT:
Enter any number: -
Negative number

demo2

import java.util.Scanner;

public class Sample {

    public static void main(String[] args) {
        int num;
        Scanner ip = new Scanner(System.in);
        System.out.print("Enter any number: ");
        num = ip.nextInt();
        if (num > )
            System.out.println("Positive number");
        else if (num < )
            System.out.println("Negative number");
        else
            System.out.println("Zero");
        ip.close();
    }
}

OUTPUT:
Enter any number:
Zero

demo3

import java.util.Scanner;

public class Sample {

    public static void main(String[] args) {
        int num;
        Scanner ip = new Scanner(System.in);
        System.out.print("Enter any number: ");
        num = ip.nextInt();
        if (num > ) {
            System.out.println("Positive number");
            if (num %  == )
                System.out.println("Even number");
            else
                System.out.println("Odd number");
        } else if (num < ) {
            System.out.println("Negative number");
            if (num %  == )
                System.out.println("Even number");
            else
                System.out.println("Odd number");
        } else
            System.out.println("Zero");
        ip.close();
    }
}

OUTPUT:
Enter any number: -
Negative number
Even number