Help me!!!!!!!: Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0

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Java

I have a problem with my main class when I build my project..

I get message :

[성적처리 프로그램]
몇명의 학생들의 data를 입력하시겠습니까?
2
1번째 학생
이름을 입력하세요 :
chos
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
at HW02_2.addinfo(HW02_2.java:18)
at HW02_2.main(HW02_2.java:95)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;


public class HW02_2 {
	public static void addinfo(int num, int[][] array) throws IOException{ // InputStream 객체에 리더를 연결
		int student_num = num;
		for(int i = 0; i < num ; i++){
		//get name info
			int intname = 0;
			InputStreamReader s = new InputStreamReader(System.in);
			BufferedReader in = new BufferedReader(s);
			 
			System.out.println(i+1+"th student\n enter name : ");
		    intname = s.read();
		    array[i][0] = intname;
        // codenumber는?[1]
            System.out.println("enter code number : ");
            Scanner codenum = new Scanner(System.in);
            array[i][1] = codenum.nextInt();
            codenum.close();
        //korean score[2]
            System.out.println("enter korean score : ");
            Scanner korscore = new Scanner(System.in);
            array[i][2] = korscore.nextInt();
            korscore.close();
        //English score[3]
            System.out.println("enter english score : ");
            Scanner engscore = new Scanner(System.in);
            array[i][3] = engscore.nextInt();
            engscore.close();
        //math score[4]
            System.out.println("enter math score : ");
            Scanner mathscore = new Scanner(System.in);
            array[i][4] = mathscore.nextInt();
            mathscore.close();
		}
		show(student_num, array);
	}
	static void show(int num, int[][] array){
		for(int i = 0; i < num ; i++){
			calculate(i, array);
		}
		// sorting by average
		int temp[] = null;
		for(int i = 0; i < num-1; i++){
			for(int j = i+1; j < num; j++){
				if(array[i][6] < array[j][6]){
					temp = array[i];
					array[i] = array[j];
					array[j] = temp;
				}
			}
		}
		// print result
		System.out.println("[Result]");
		for(int i = 0; i < num; i++){
			char grade = 'F';
			if(array[i][6] >= 90){
				grade = 'A';
			}else if(array[i][6] >= 80 && array[i][6] <= 89){
				grade = 'B';
			}else if(array[i][6] >= 70 && array[i][6] <= 79){
				grade = 'C';
			}else if(array[i][6] >= 60 && array[i][6] <= 69){
				grade = 'D';
			}else if(array[i][6] < 60){
				grade = 'F';
			}
			
			System.out.print((char)array[i][0]+""+array[i][1]+" "+array[i][2]+" "
			+array[i][3]+" "+array[i][4]+" "+array[i][5]+" "+array[i][6]+" "+grade+" "+i+1);
		}
	}
	static void calculate(int i, int[][]array){
		//total[5]
		for(int j = 2; j == 4; j++){
			array[i][5] += array[i][j];
		}
		//average[6]
		array[i][6] = array[i][5] / 3;
	}
	public static void main(String[] args) throws IOException {
		int[][] studentinfo = {};
		int students_num = 0;
		
			System.out.println("[성적처리 프로그램]\n몇명의 학생들의 data를 입력하시겠습니까?"); 
			Scanner s = new Scanner(System.in);
			students_num = s.nextInt();
			
			addinfo(students_num, studentinfo);
			s.close();
			
		
	}
}