Q:

Error code compiling: illegal start of expression

Output Error :
Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - illegal start of expression
I'm creating a class that calculate 1 student that take 3 quizzes 25%, 1 Midterm 25% , and 1 Final 50%
package Grading;

import java.util.Scanner;

public class Grading {

    public static void main(String[] args) {

    Scanner input =new Scanner(System.in);
    public static double quiz1, quiz2, quiz3, midterm, finalExam, Grades, totalGrade, bothQuizzes, PfinalExam, PmidTerm;
    public static String studentname;
    public static int Score;

    public String getstudentname( )
    {
        return studentname;
    }
    public double getquiz1()
    {
        return quiz1;
    }

    public double getquiz2 ()
    {
        return quiz2;
    }
public double getquiz3 ()
    {
        return quiz3;
    }
    public double midterm()
    {
        return midterm;
    }

    public double finalExam()
    {
        return finalExam;
    }

    public void setquiz1 (double quiz1)
    {
        this.quiz1 = quiz1;
    }

    public void setquiz2 (double quiz2)
    {
        this.quiz2 = quiz2;
    }
    public void setquiz3 (double quiz3)
    {
        this.quiz3 = quiz3;
    }

    public void setmidterm()
    {
        this.midterm = midterm;
    }

    public void setfinalExam()
    {
        this.finalExam = finalExam;
    }

    public void setGrades ()
    {

    }

    public String toString(){

        return this.quiz1 + " " + this.quiz2 + this.quiz3 + " " + this.midterm + " " + this.finalExam;

    }

    public static void  readInput(){

        System.out.println("Please enter the grade you got for the first quiz: ");
        quiz1 = grades.nextInt();

        while (quiz1 <0 || quiz1>10)
        {
            System.out.println("Please enter a grade between zero and ten: ");
            quiz1 = grades.nextInt();
        }

        System.out.println("Please enter the grade you got for the second quiz: ");
        quiz2 = grades.nextInt();

        while (quiz2 <0 || quiz2>10)

        {
            System.out.println("Please enter a grade between zero and ten: ");
            quiz2 = grades.nextInt();
        }

        System.out.println("Please enter the grade you got for the third quiz: ");
        quiz3 = grades.nextInt();

        while (quiz3 <0 || quiz3>10)

        {
            System.out.println("Please enter a grade between zero and ten: ");
            quiz3 = grades.nextInt();
        }

        System.out.println("Please enter the grade you got on your midterm: ");
        midterm = grades.nextInt();

        while (midterm <0 || midterm>100)

        {
            System.out.println("Please enter a grade between 0 and 100: ");
            midterm = grades.nextInt();
        }

        System.out.println("Please enter the grade you got on your final exam: ");
        finalExam = grades.nextInt();

        while (finalExam < 0 || finalExam > 100)

        {
            System.out.println("Please enter a grade between 0 and 100: ");
            finalExam = grades.nextInt();
        }
    }

    public static  void output()

    {

        System.out.println(" your score for the first quiz was " + quiz1 );

        System.out.println("your score for the second quiz was " + quiz2);

        System.out.println("your score for the third quiz was " + quiz3);

        System.out.println(" your score for the midterm was " + midterm );

        System.out.println("your score for the final exam was " + finalExam);
        bothQuizzes = ((quiz1 + quiz2 + quiz3)/100)*.25;
        PmidTerm = (midterm/100) *.35;
        PfinalExam = (finalExam/100) * .40;

        System.out.println("Your total grade for these grades is " + totalGrade + "%");

        System.out.println("Your total grade for these grades is " + totalGrade);

        double letterGrade = totalGrade;
        if (letterGrade >= 90)

        {

            System.out.println("Your grade is an A");

            // grade = "A";

        }

        else if (letterGrade >= 80)

        {

            System.out.println("Your grade is a B");

        }

        else if (letterGrade >= 70)

        {

            System.out.println("Your grade is a C");

        }

        else if (letterGrade >= 60)

        {

            System.out.println("Your grade is a D");

        }

        else

        {

            System.out.println("Your grade is an F");

        }

    }}

A:

I have re-written your program. I hope that this is what you wanted to achieve.  I didn't know how you wanted to count the grade, so I've marked the place where you can change that code with a comment.
Since there were some major problems in your code with field declaration and function bodies, I've reorganized them. You can take a look at this code:
import java.util.Scanner;

public class Grading {
     private int quiz1, quiz2, quiz3, midterm, finalExam; //quizzes exams tests what grades

public void readInput () {
    Scanner in = new Scanner(System.in);
    System.out.print("Please enter the grade you got for the first quiz: ");
    quiz1 = readInt(in, 0, 10);

    System.out.print("Please enter the grade you got for the second quiz: ");
    quiz2 = readInt(in, 0, 10);

    System.out.print("Please enter the grade you got for the third quiz: ");
    quiz3 = readInt(in, 0, 10);

    System.out.print("Please enter the grade you got on your midterm: ");
    midterm = readInt(in, 0, 100);

    System.out.print("Please enter the grade you got on your final exam: ");
    finalExam = readInt(in, 0, 100);
}

public void output () {
    System.out.println("Your score for the first quiz was " + quiz1);
    System.out.println("Your score for the second quiz was " + quiz2);
    System.out.println("Your score for the third quiz was " + quiz3);
    System.out.println("Your score for the midterm was " + midterm);
    System.out.println("Your score for the final exam was " + finalExam);

    //dunno if this is the way you want to count it; change as needed
    double quizzes    = (quiz1 + quiz2 + quiz3) / 100 * 0.25;
    double Pmidterm   = midterm / 100 * 0.25;
    double PfinalExam = finalExam /100 * 0.50;
    double totalGrade = (quizzes + Pmidterm + PfinalExam) * 100.0;

    char grade;
    if (totalGrade >= 90)
        grade = 'A';
    else if (totalGrade >= 80)
        grade = 'B';
    else if (totalGrade >= 70)
        grade = 'C';
    else if (totalGrade >= 60)
        grade = 'D';
    else grade = 'F';

    System.out.printf("Your grade is %c\n", grade);
}

private int readInt (Scanner in, int min, int max) {
    int value = in.nextInt();
    if (value < min || value > max) {
        System.out.printf("Please enter a grade between %d and %d: ", min, max);
        return readInt(in, min, max);
    }
    return value;
}

public static void main(String[] args) {
    Grading grading = new Grading();
    grading.readInput();
    grading.output();
}
}

