Null pointer exception in Java despite having initialized the varibale

public class GradeClass {
String nameF;
int[] gradesF = new int[4];
float average;
public GradeClass(String name, int grade1, int grade2, int grade3, int grade4) {
nameF = name;
gradesF[0] = grade1;
gradesF[1] = grade2;
gradesF[2] = grade3;
gradesF[3] = grade4;
}
public float getAverage() {
average = (gradesF[0] + gradesF[1] + gradesF[2] + gradesF[3] / gradesF.length);
return average;
}
// Used to reference number of sides used in current state of die.
public String getName() {
return nameF;
}
// Used to reference number of sides used in current state of die.
public int[] getGrades() {
return gradesF;
}	

}

   else if (a == 2) {
System.out.println("Enter name of  "+ (a+1)  +" person. :: ");
nameI = keyboard.next();
while (size < 1 || size > 4 ) {
System.out.println("How many grades would you like to enter? 'Max-4' :: ");
size = keyboard.nextInt();
}
while (gradeArray[b] > 1 || gradeArray[b] > 100 ) {
System.out.println("Enter the " + size + " grades here :: ");
for(b=0; b<size; b++) {
gradeArray[b] = keyboard.nextInt();
}
GradeClass student3 = new GradeClass(nameI, gradeArray[0],gradeArray[1],gradeArray[2],gradeArray[3]);
}	}	
else {
numPersons = 0;
}
}
grade1A = student1.gradesF[0] + student2.gradesF[0] + student3.gradesF[0];
averageA = student1.average + student2.average + student3.average;
System.out.println("Name \t\t Grade 1 \t Grade 2 \t Grade 3 \t Grade 4 \t Average \n");
System.out.println(student1.getName() + "\t" + student1.gradesF[0] +"\t" +student1.gradesF[1]+"\t" +student1.gradesF[2] +"\t" + student1.gradesF[3] + student1.average + "\n");
System.out.println("Average\t\t" + grade1A + "\t" + grade2A + "\t"  + grade3A + "\t"  + grade4A + "\t" + averageA + "\n");
}}

In my main im trying to call on another instance of a class. What it needs to do is take number of participants, there names, how many grades they have, their grades, enter all grades into an array, send the name along with the grades to gradeClass and allow for me to call and use them from there.

    gradeClass student1 = new gradeClass(nameI, gradeArray[0],gradeArray[1],gradeArray[2],gradeArray[3]);

when i try to use this it tells me i need a variable

    gradeClass student1;
student1 = new gradeClass(nameI, gradeArray[0],gradeArray[1],gradeArray[2],gradeArray[3]);

then it tells me to initialize student1 so

    gradeClass student1 = null;

from here i get "java.lang.NullPointerException

any ideas? Error is being called at

    student1 = new gradeClass(nameI, gradeArray[0],gradeArray[1],gradeArray[2],gradeArray[3]);

First of all class names should start with an upper case character. Follow Java conventions.

> despite having initialized the varibale

int[] gradesF;

You have defined a variable, but the variable is null because you have not specified the size of the array.

    gradesF[0] = grade1;
gradesF[1] = grade2;
gradesF[2] = grade3;
gradesF[3] = grade4;

You can't just attempt to assign values to the Array without first defining the size of the Array.

You define an Array with code like:

int[] gradesF = new int[4];

Now you can assign the 4 values in the array, using the code you have above.

Edit:

gradeClass student1;
student1 = new gradeClass(nameI, gradeArray[0],gradeArray[1],gradeArray[2],gradeArray[3]);

First of all there is no need to do that in two statements, so most people would do:

gradeClass student1 = new gradeClass(nameI, gradeArray[0], gradeArray[1], gradeArray[2], gradeArray[3]);

But the problem is that in the code you posted you never create a "gradeArray" variable and initialize it with a value. You can't just use a variable without first declaring it.

ok i figured out what was wrong, the
GradeClass student3 = new GradeClass(nameI, gradeArray[0],gradeArray[1],gradeArray[2],gradeArray[3]);

was inside a if/else statement and wouldn't allow me to call for it outside it. I had to send it to the class inside the if/else statement and then call for it again inside the if/else statement and assign it to a new variable. Thanks for the help!