java题 请输入一个数 判断这个数是正数 负数 零 。输出零的时候显示是＂这个数是0＂。谢谢~(>_<)

public class Main
{
public static void main(String args[]) throws IOException
{
int a;
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("输入一个数：");
a=Integer.parseInt(br.readLine());
if(a>0)
{
System.out.println("这个数是正数");
}else if(a<0){
System.out.println("这个数是负数");
}else{
System.out.println("这个数是0");
}
}
}

import java.util.Scanner;
public class studentgrade {
public static void main(String args[]){
int grade;
System.out.println("请输入数");
grade = new Scanner(System.in).nextInt();

if(grade>0){
System.out.print("这个数正数");
}else{
if(grade==0){
System.out.print("这个数是0");
}else{
System.out.print("这个数负数");
}

}
}
}

package buke;
import java.util.Scanner;
public class $eeqe {
public static void main (String [] args){
System.out.println("请输入一个整数");
Scanner sc=new Scanner(System.in);
int v=sc.nextInt();
System.out.print(v>0?"正":"负");
}
}
0怎么搞进去