How to get variable from another class?

Question

I have 2 classes. In first I have int variable. In second class I need to get this variable value. How I can make it?
import javax.microedition.lcdui.*;
import java.io.*;
import java.util.*;
public class ChooseLessons extends Form implements CommandListener, ItemStateListener
     ChoiceGroup lessons;     // Choice Group of preferences
     Dictionary     dictionary;
     int volumeSize;
     ChooseLessons(Dictionary dictionary)
          int volumeSize = 15;
     public void commandAction(Command c, Displayable s)
          if (c == Dictionary.BEGIN_CMD) {
               new TeachForm(dictionary, this);
import javax.microedition.lcdui.*;
import java.util.*;
public class TeachForm extends Form implements CommandListener     
     Dictionary               dictionary;
     ChooseLessons          lessons;
     TeachForm(Dictionary dictionary, ChooseLessons lessons) {
          super(Locale.WORD);
          this.dictionary = dictionary;
          this.lessons = lessons;
          lessons.volumeSize(); // HERE I NEED VARIABLE VALUE FROM PREVIOUS CLASS
}Edited by: Djanym on Mar 16, 2009 4:43 PM

Answer 1

This is a classic problem that coders run into when trying to get their head around object-oriented programing. Since you have a class that should be modeled after a real world object, as far as that object is concerned, no one else needs to know the details of it - without asking nicely. This is where you should set up some getters and setters, which are methods that allow fields in a class to reveal themselves or allow their states to be changed in a orderly fashion.
There are a number of fields that never need to be known outside of the class. Then there are some fields you would like to let people know about, but don't want them to have the ability to change them. In the example below, there are to getter methods allow return of the necessary fields. If you made these public, there is a possibility that someone utilizing this field may change it outside of its intended use, or access them without them being ready for public consumption.
Class test {
//These private variables are only visible from the class
private int grade1 = 0;
private int grade2 = 0;
private int grade3 = 0;
private float average = 0;
private int gradeboost = 0;
//This method sets the gradeboost field to one desired by the instructor
void setboost(int boost) {
gradeboost = boost;
//These methods accept test scores and compute the average for three test
//Notice that the calculated average may not be the true average of the three test scores
//because of the possibility of gradeboost calculation being greater than 1
void test1(int score) {
         grade1 = score;
         average = (grade1 + grade2 + grade3 + gradeboost)/3;
void test2(int score) {
         grade2 = score;
         average = (grade1 + grade2 + grade3 + gradeboost)/3;
void test3(int score) {
         grade3 = score;
         average = (grade1 + grade2 + grade3 + gradeboost)/3;
//This is a getter method, which provides read access to the private variable average
//If someone just had public access to the grades and wanted to take their own average
//They would miss how the gradeboost field affects the final outcome.
float getAverage() {
    return average;
//Here is a getter method, which accepts an argument to determine which test score to return
//Notice that this isn't the true testscore, but it has been modified by the gradeboost field.
//If the user had public access to the true testscore, it wouldn't take into account the gradeboost calculation!!
//This is how a getter can control exactly what a user has access to.
float get testScore(int test) {
float testresult = 0;
if (test = 1) {
       testresult = (grade1+ gradeboost) / 3;
if (test = 2) {
       testresult = (grade2+ gradeboost) / 3;
if (test = 3) {
       testresult = (grade3+ gradeboost) / 3;
return testresult;
}