Thread: can someone help with this error?

Hi I'm a beginner in java. I have some problem with my code.
can someone help me?

import java.util.Scanner;
 
 
public class HW11of2 { 
 
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner console = new Scanner(System.in); 
		student[] students=new student[4];
		for(int i=0;i<students.length;i++){
 
			System.out.println("Please enter the name: ");  
	        students[i].name = console.nextLine();  
			System.out.println("Please enter a number for the id: ");  
	        students[i].id = console.nextInt();  
	        int sum=0;
	        for(int j=0;j<5;j++){
	        	System.out.println("Please enter the grade: ");  
		        students[i].grades[j] = console.nextInt();
		        sum=sum+ students[i].grades[j];
	        }
	        students[i].avg=sum/5;
		}
		int avgtotal=0;
		 for(int i=0;i<students.length;i++){
			 avgtotal=avgtotal + students[i].grades[2];
		 }
		 System.out.println(avgtotal);
		 int min=min(students[0].grades);
		 for(int i=1;i<students.length;i++){
			 int temp=min(students[i].grades);
			 if(temp<min){
				 min=temp;
			 }
		 }
		 int max=max(students[0].grades);
		 for(int i=1;i<students.length;i++){
			 int temp=max(students[i].grades);
			 if(temp>max){
				 max=temp;
			 }
		 }
        console.close();
	}
 
	public static int min(int[] x){
		int min=x[0];
		for (int i=0; i<x.length;i++)
		{
			if (x[i]<min)
			{
				min=x[i];
			}
		}
		return min;
	}
	public static int max(int[] x){
		int max=x[0];
		for (int i=0; i<x.length;i++)
		{
			if (x[i]>max)
			{
				max=x[i];
			}
		}
		return max;
	}
	public class student
	{
		int id;
		String name;
		int[] grades=new int[5];
		int avg;
	}
}

and the error I get is:

Exception in thread "main" java.lang.NullPointerException
	at HW11of2.main(HW11of2.java:13)

Thanks!

Welcome to the forum! Thanks for taking the time to learn to post your code correctly and ask a complete question.

In Java, class names begin with capital letters, even inner classes.

This line:

student[] students = new student[4];

creates an array that is large enough to hold 4 Student objects, but it doesn't add create or add any student objects to the array.

So in this and similar subsequent lines:

students[i].name = console.nextLine();

the reference to students[i] is null. Each element of students[] must first be filled with a Student instance, as in:

students[i] = new Student();

Hope this helps.

Thanks!
that helped and also I've forgot to put static where the class of students.