Object oriented

Question

I have completed a program that assigns letter grades to students and displays average.
Now i have to take this application and implement it into two separate java files one for implementation and the other for its definition (object oriented)
I have absolutely no clue on where to begin.
Im not asking for anyone to do this for me but i would apppreciate any advice, tips, or references i can use to guide me to breaking down my program into two files.
Thanks!
import javax.swing.*;
public class Grade {
     static final int MAX = 40;
     static final int MIDTERM = 25;
     static final int FINAL = 35;
     static final int ASSIGNMENTS = 25;
     static final int PROJECT = 15;
     public static void main (String [] args)
          int [] midterm = new int [MAX], finalExam = new int [MAX],
               assignments = new int [MAX], project = new int [MAX];
          String [] names = new String [MAX];
          int num;
          num = howMany();
          enterStudents(names, midterm, finalExam, assignments, project, num);
          output (names, midterm, finalExam, assignments, project, num);
     private static int howMany()
     { int number;
       number = Integer.parseInt(JOptionPane.showInputDialog("Enter number of students in this class: "));
       while (number < 0 || number > MAX)
             number = Integer.parseInt(JOptionPane.showInputDialog("ERROR -- maximum class size is "+MAX+" Enter number of students in this class: "));
       return number;
      private static int score(String requirement, String name)
           int value;
           value = Integer.parseInt(JOptionPane.showInputDialog("Enter " + requirement+" score for "+name+": "));
          while (value < 0 || value > 100)
               value = Integer.parseInt(JOptionPane.showInputDialog("ERROR -- this value represents a percentage and must be between 0 and 100, try again\n Enter " + requirement+" score for "+name+": "));
            return value;
       private static void enterStudents(String [] snames, int [] smids, int [] sfin, int [] sass, int [] sproj, int n)
            for (int i = 0; i < n; i++)
                 snames[i] = JOptionPane.showInputDialog( "Enter student "+(i+1)+"'s name: ");
                 smids[i] = score ("Midterm Exam", snames);
               sfin[i] = score ("Final Exam", snames[i]);
               sass[i] = score ("Assignments", snames[i]);
               sproj[i] = score ("Project", snames[i]);
     private static String letterGrade (int percent)
          switch (percent/10)
               case 9:
               case 10: return "A";
               case 8: return "B";
               case 7: return "C";
               case 6: return "D";
               default: return "F";
     private static int computeGrade (int mid, int fin, int assn, int proj)
          return (mid*MIDTERM+fin*FINAL+assn*ASSIGNMENTS+proj*PROJECT)/100;
     private static void output(String [] snames, int [] smids, int [] sfin, int [] sass, int [] sproj, int n)
          String info="Name Grade\n";
          int grade, total=0;
          for (int i = 0; i < n; i++)
          {System.out.println(info);
               grade=computeGrade(smids[i], sfin[i], sass[i], sproj[i]);
               total+=grade;
               info+= snames[i]+" " letterGrade(grade)"\n";
          JOptionPane.showMessageDialog(null, info + "\n-------------------------\nClass Average: "+ total/n);

Answer 1

Something like this
import javax.swing.JOptionPane;
public class SwimmerDefinition{
     public static void main(String[] args){
     implementation i=new implementation();
     int time1, time2;                      //integers for the two trials of the race
     String name = JOptionPane.showInputDialog(null,
          "Please enter the name of the swimmer");   //prompts the user for the swimmers name
     i.setName(name);     
     String minutes1 = JOptionPane.showInputDialog(null,
          "Enter minutes of swimmer " + name);          //asks for the minutes of swimmers race for trial 1
     int m = Integer.parseInt(minutes1);
     String seconds1 = JOptionPane.showInputDialog(null,
          "Enter seconds of swimmer " + name);              //asks for the seconds of swimmers race for trial 1
     int s = Integer.parseInt(seconds1);
     i.setTime(m,s);
      time1=i.getTime();
     String minutes2 = JOptionPane.showInputDialog(null,
          "Enter minutes of swimmer " + name + " for trial 2 "); //asks for the minutes of swimmers race for trial 2
     int m2 = Integer.parseInt(minutes2);
     String seconds2 = JOptionPane.showInputDialog(null,
          "Enter seconds of swimmer " + name + " for trial 2 "); //asks for the seconds of swimmers race for trial 2
     int s2 = Integer.parseInt(seconds2);
     i.setTime(m2,s2);
      time2=i.getTime();
     if(i.bestTime(time1,time2))
     JOptionPane.showMessageDialog(null,"Best time of "+i.getName()+" is"+time2/60+ " minutes " +time2%60+ " seconds ");  //compares two trials for the best times between the two, then outputs the best one
     else
     JOptionPane.showMessageDialog(null,"Best time of "+i.getName()+" is"+time1/60+ " minutes " +time1%60+ " seconds ");
}class implementation{
String name;
     int time; //declaring variables
     public String getName () {return name;} //returns name
     public int getTime () {return time;} //returns time
     public void setName(String n) { name = n;} //sets name
     public void setTime (int m, int s) {   //sets time in minutes and seconds
          if (m>0 && m < 20 && s >= 0 && s < 60)
               time = 60*m + s;
     public boolean bestTime (int m, int s)
          if (m>s){
               return true;} //boolean to determine the best time in minutes and seconds
          else
          return false;