You created the array but didn't put anything in it, so you have an array that contains 5 elements, all of which are null. You could add

boll[0] = new ResultList();

before the line where you set boll[0].name.

As your code is currently written,

CopySystem.out.println(studentArray[0].getFirstName());

Will throw an NPE since you're never initializing the array.

Copyprivate static students[] studentArray;

Just declares it, doesn't initialize it.

Maybe you should refactor your code as follows

Copyprivate static ArrayList<students> studentArray = new ArrayList<students>();

// Inside the constructor or some method called before you access studentArray:
studentArray.add(stu1);
studentArray.add(stu2);
//...

// or, more concisely, since you're not using the temporary `students` variables:
studentArray.add(new students(65435, "Bob", "Ted"));
studentArray.add(new students(45546, "Guy", "Sid"));
//...

If you're committed to using an array and not a List,

Copyprivate static students[] studentArray;

needs to be initialized with something like

Copyprivate static students[] studentArray = new students[10];

and then you need to assign its elements

CopystudentArray[0] = stu1;

or

CopystudentArray[0] = new students(65435, "Bob", "Ted");

Because you never initialized the array with any values, so it just contains a bunch of nulls. You need to give it values before you can call .toString() on them.

For example:

Integer[] array = new Integer[5] { 1, 2, 3, 4, 5 };

Your initial loop (x = -1} is not changing the array, but rather the transient object x in your loop. It would be like doing this:

for (int i = 0; i < array.length; i++) {
    Integer j = array[i];
    j = -1;
}

Instead, do this if you want to use a loop to initialize:

for (int i = 0; i < array.length; i++) {
    array[i] = -1;
}

The array isn't null.

The exception is thrown when you try to call a method on a null member of the array.

You iterate over the full array, but have not necessarily filled the entire array. Members that you have not assigned to reference an object are null.

for (int a = 0; a < list.length; a++) { //To Display all current Student Information.
    //   list[i] = new student();
    list[a].DisplayOutput();
}

One fix would be to stop iterating after you've hit the first null.

for (int a = 0; a < list.length; a++) { //To Display all current Student Information.
    //   list[i] = new student();
    student student = list[a];
    if ( null == student ) {
       break;
    }
    else {
       list[a].DisplayOutput();
    }
}

Another fix would be to remember in case 1 how many students were stored, and change the loop condition to reflect that.

for (int a = 0; a < cntStudents; a++) { //To Display all current Student Information.

By the way, in Java code it is almost universally accepted that:

• Class names begin with an uppercase character.
• Method names begin with a lowercase character.