[JAVA] Auxiliary Class Help

[piehouserat]

Can someone please explain as easily as possible how to create a java program that handles all the user input in one program and then uses an auxiliary class (a seperate java file) to perform the calculations. I have trouble understanding how the entered data is passed to the auxiliary class file for processing.

So for example, this program could prompt for 3 numbers to be entered using JOptionPane.showInputDialog's and these numbers are then fed to the auxiliary class file which adds these numbers together and passes the total back to the main program which then uses a JOptionPane.showMessageDialog to display the total.

I'm really not that good with java so the simpler its explained the better, thx :D

[_kane81]

A class is your blue print (not really but close enough).....

When you run an application you create "Instances of the Class" so in memory you might have 5 people instances with different names ... ie

Person.java

public class Person {
  private String name;

  public Person(String name) {
	this.name=name;
  }
  public String getName(){
	 return name;
  }
}

main code

public static void main (String[] arg) {
  //create instances of person class
   Person p1 = new Person("John");
   Person p2 = new Person("Luke");
   Person p3 = new Person("Mary");

}  

now we will add another class file

Bus.java

public class Bus {
  private String busName;
  private ArrayList peopleOnTheBus = new ArrayList();  

  public Bus(String name) {
	this.busName=name;
  }

  public String getName() {
	return this.busName;=name;
  }

  public void addPerson(Person p) {
  peopleOnTheBus.add(p);
  }
}

so now bringing all instances of classes together and interacting

public static void main (String[] arg) {
  //create instances of person class
   Person p1 = new Person("John");
   Person p2 = new Person("Luke");
   Person p3 = new Person("Mary");

   Bus b1 = new Bus("A");
   Bus b2 = new Bus("B");

   b1.add(p1);
   b1.add(p3);

   b2.add(p2);
}  

[piehouserat]

well ok... i think i got bits of that but any chance of more basic and easier to understand examples?

sure i could google around and find a tutorial somewhere but im looking for an explanation thats super easy to understand, perhaps the actual parts where the auxiliary class links to the main program could be highlighted?

[_kane81]

Main.java

public class Main {
   public static void main (String[] args) {

	 Auxiliary aux = new Auxiliary();
	 GUI g = new GUI(aux);
	 g.setVisible(true);
   }
} 

GUI.java

public class GUI {

  public GUI(ActionListener al) {
	 button.setActionCommand("START");
	 button.addListener(al); // the button registers the ActionListener to be notified of changes/button presses
	 .... 
  }


  .. gui stuff
}

Auxiliary.java - ActionListener is an interface that defines how you listen to button events etc

public class Auxiliary implements ActionListener{

  public void ActionPerformed(ActionEvent e) {
	... do some action based on what was pressed/action performed - method is called when button is pressed

	if (e.getActionCommand().equals("START"))
		System.out.println("Startgame"); 
  }
}

[piehouserat]

thanks a lot, thats way more helpful, ahh i'm so crap at programming but i have no problem coding html and css :D

[_kane81]

^ thats cause html and css is not a programming language...

[konstantinos]

^thats cold...

i hardly know a coder who didn't start out making websites!

[piehouserat]

don't worry about it, i'm sure ill get the hang of programming at some point...

[_kane81]

^^

wasn't meant to be cold, just a fact that they are different..... each has its place in the industry