I keep getting zeros from a method
<p>This is the main method </p>

<pre><code>package javaapplication50;

import java.util.Scanner;

public class JavaApplication50 {

    public static void main(String[] args) {

                System.out.print(" &gt; Enter student ID: ");

                int id = in.nextInt();

                System.out.print("&gt; Enter student First Name: ");

                String name = in.next();

                System.out.print("&gt; Enter student Last Name: ");
                String last = in.next();

                JavaApplication50 app = new JavaApplication50();

                System.out.println(" &gt; Enter students Grades: ");

                double aptTestGrade = app.readStudentGrade(0, 100, " &gt; Enter the grade of Aptitude Test: ", in);
                double introYearGrade = app.readStudentGrade(0, 100, " &gt; Enter the grade of Introductory Year: ", in);
                double schoolGrade = app.readStudentGrade(0, 100, " &gt; Enter the grade of School: ", in);

                System.out.println("");

                String AF;

                double finalgrade = 0;

                calculateFinalGrades(aptTestGrade, introYearGrade, schoolGrade);

                if (finalgrade &gt;= 90 &amp;&amp; finalgrade &lt;= 100) {

                    AF = "Medicine";

                } else if (finalgrade &gt;= 85 &amp;&amp; finalgrade &lt;= 90) {

                    AF = "Engineering";
                } else if (finalgrade &gt;= 80 &amp;&amp; finalgrade &lt;= 85) {
                    AF = "Computing";

                } else if (finalgrade &gt;= 75 &amp;&amp; finalgrade &lt;= 80) {
                    AF = "Science";

                } else if (finalgrade &gt;= 70 &amp;&amp; finalgrade &lt;= 75) {

                    AF = "Economics";

                } else {

                    AF = "Not Assigned";

                }

                System.out.println("&gt; " + name + " " + last + " (ID #" + id + ") has been added to the system.");

                System.out.println("&gt; Final Grade:  " + finalgrade + "  Assigned Faculty:  " + AF);
</code></pre>

<p>I used this method to enforce the user to enter test grade between 0 and 100.</p>

<pre><code>    double readStudentGrade(double min, double max, String message, Scanner in) {
        while (true) {
            System.out.print(message);
            double input = in.nextDouble();
            if (input &lt;= max &amp;&amp; input &gt;= min) {
                return input;
            } else {
                System.out.println("");
                System.out.println(" &gt;    Invalid input! ((must be between " + min + " and " + max + ")");
                System.out.println(" &gt;    Please try again.\n"
                        + "");
                System.out.println("");
            }
        }

    }
</code></pre>

<p>this method is to calculate the final grade but for some reason I keep getting zero as grade .</p>

<pre><code>public static double calculateFinalGrades(double aptTestGrade, double introYearGrade, double schoolGrade) {

    double finalgrade;

    double finalgrade1 = (aptTestGrade * 30) / 100;

    double finalgrade2 = (introYearGrade * 50) / 100;

    double finalgrade3 = (schoolGrade * 20) / 100;

    finalgrade = finalgrade1 + finalgrade2 + finalgrade3;

    return finalgrade;

}
</code></pre>

<p>Thanks in advance.</p>