if(条件){执行内容}

import java.util.Scanner;
public class For02{
    public static void main(String[] args){
    
    Scanner myScanner = new Scanner(System.in);
    System.out.println("判断输入的数，大于0，小于0，等于0");
    System.out.println("请输入一个数字");
    int num = myScanner.nextInt();

    if (num<0){
        System.out.println("小于0");
        
    }else if (num==0){
        System.out.println("等于0");
        

    }else{
        System.out.println("大于0");


    }


    
    } //结束主方法
                                          
}