Why it shows "exception in thread "main" java.lang.NullPointerException at TestArray.main(TestArray.java:11)"

Question

class Student
{
int marks;
}

class TestArray
{
public static void main (String []args)
{
Student[] studentArray = new Student[7];
studentArray[0].marks = 100;
System.out.println(studentArray[0].marks);
}
}

Answer 1

It's because your array is empty (filled with nulls). You have to fill it with Student instances first (or/and check for nulls before accessing Student properties.

Answer 2

studentArray[0] doesn't point to any instance of Student. To make that happen, write:

studentArray[0] = new Student();

Answer 3

ohhhh ok ok.. tqq now i understand