Adding item to an ArrayList

Question

I have an array list of Fleets (Each fleet will hold its own list of Trucks).

I have a fleet class with the constructor

public Fleet(String businessName){
    this.businessName = businessName;
    this.fleetList = new ArrayList<Truck>();
}

So:

In my TUI, I have a helper method called createFleet. When the user presses 1 on the menu, it asks for a name of his business, and then makes a fleet named that. That method is:

public static void createFleet(){
    System.out.println("");
    System.out.println("Please enter the name of the fleet.");
    inputText = scan.nextLine();

    fleetCollection.add(new Fleet(inputText));
    printFleets();
    System.out.println("");
    System.out.println("--- Fleet: " + inputText + " added ---");
    System.out.println("");
}

And my problem is that when I add one Fleet, and print the results I get:

Fleet 0: Fleet Number One

But when I add Fleet Number One, then press 1 on the menu again to add ANOTHER fleet (named Fleet Number Two) and print the fleet list, the results are:

Fleet 0: Fleet Number Two
Fleet 1: Fleet Number Two

It seems to be confusing the two...and this further breaks the program when I try to add trucks to the fleet, because It cannot pick the "right" fleet.

Please let me know if you need any other of my code. I just need this to correctly add and print the fleets in the fleet list:

private static ArrayList<Fleet> fleetCollection;

Thank you :) for all the help!

can you post code of printFleets() method?

JProgrammer
– JProgrammer

2012-02-28 06:37:20 +00:00
Commented Feb 28, 2012 at 6:37 — JProgrammer
– JProgrammer, Commented Feb 28, 2012 at 6:37
Hey man.... where is your question??

gtiwari333
– gtiwari333

2012-02-28 07:14:14 +00:00
Commented Feb 28, 2012 at 7:14 — gtiwari333
– gtiwari333, Commented Feb 28, 2012 at 7:14

Nirmal- thInk beYond · Accepted Answer · 2012-02-28 06:42:46Z

3

You probably declared businessName in Fleet class static, if so then remove it

answered Feb 28, 2012 at 6:42

Nirmal- thInk beYond

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4 Comments

plucury Over a year ago

In that case,getBusinessName() should be NOT static too

Nirmal- thInk beYond Over a year ago

remove method modifier static of getBusinessName()

Nirmal- thInk beYond Over a year ago

remove method modifier static of fleetList

Nirmal- thInk beYond Over a year ago

use fleet.getBusinessName() instead of Fleet.getBusinessName(); // use fleet object, do not use as static

gtiwari333 · Accepted Answer · 2012-02-28 06:52:27Z

You need to be clear about use of static

static variable

It is a variable which belongs to the class and not to object(instance)
Static variables are initialized only once , at the start of the execution . These variables will be initialized first, before the initialization of any instance variables
A single copy to be shared by all instances of the class
A static variable can be accessed directly by the class name and doesn’t need any object
Syntax : <class-name>.<variable-name>

static method

It is a method which belongs to the class and not to the object(instance)
A static method can access only static data. It can not access non-static data (instance variables)
A static method can call only other static methods and can not call a non-static method from it.
A static method can be accessed directly by the class name and doesn’t need any object
Syntax : <class-name>.<method-name>
A static method cannot refer to "this" or "super" keywords in anyway

src : http://www.javatutorialhub.com/java-static-variable-methods.html

Tom · Accepted Answer · 2012-02-28 06:57:44Z

2

have you overridden the equals method in Fleet ? if so and it's not correct, it could be the cause of your weird result

answered Feb 28, 2012 at 6:57

Tom

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2 Comments

Tom Over a year ago

you need an instance from that class to be able to call a non-static method; like this: Object a = new Object(); a.method();

user1176922 Over a year ago

Should I open a new question for that problem? Or should I erase everything above, and post the new question here?

John Eipe · Accepted Answer · 2012-02-28 06:50:55Z

I made small modifications to your program to make it simple.

class Fleet{
String businessName;
public Fleet(String businessName)
{ this.businessName = businessName;}
public String getBusinessName()
{
    return businessName;
}
}

public class T {
private static ArrayList<Fleet> fleetCollection = new ArrayList<Fleet>();

    public static void main(String[] args) 
    {
        createFleet("A");
         printFleets();
         createFleet("B");
        printFleets();
    }
     public static void createFleet(String name){
    System.out.println("");
    fleetCollection.add(new Fleet(name));
}
public static void printFleets(){
    Iterator i = fleetCollection.iterator();
    Fleet f;
    while(i.hasNext())
    {
        f = (Fleet)i.next();
        System.out.println(f.getBusinessName());
    }
}

}

It prints as expected.

A

A
B

Check your access modifiers on "businessName" field. It shouldn't be static. Also check printFleets() method.

Thank you :) It now returns the fleets properly but my addTruck() is still broken.

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