Dynamic variable names in Java so each new object has separate name

Question

How can I do such a thing?

String N = jTextField0.getText();
MyClass (N) = new Myclass();

Is it even possibe? Or as my question's explains, how can I just make a method to create a new object of my specified class just with a different name each time I call it. I really searched everywhere with no luck. Thanks in Advance

P.S. I wish you guys can excuse me for not being clear enough, Just to say it as it is, I made a textfield to get the name of someone who wants to make an account, and I made a class named "Customer". and a button named "Add". Now I want every time "Add" is clicked, compiler take what is in my textfield and make an object of the class "Customer" named with what it took from the textfield

It was too hard to read it in comments so I updated my question again, so sorry. I'm stuck so bad. I suppose my problem is that I didn't "understand" what you did and only tried to copy it. This is what I wrote:

private void AddB0MouseClicked(java.awt.event.MouseEvent evt) {
    String name = NameT0.getText();
    Customer instance = new Customer(Name);
    Customer.customers.add(instance);

and this is my Customer class:

public class Customer{
String name;
public Customer(String name){
this.name = name;
}
public String getName(){
    return name;
    }
static ArrayList<Customer> customers = new ArrayList<Customer>();

It's not really clear what you're asking, there are already 3 responses answering very different questions. — darrengorman
– darrengorman, Commented Nov 24, 2012 at 22:30
I wish you guys can excuse me for not being clear enough, Just to say it as it is, I made a textfield to get the name of someone who wants to make an account, and I made a class named "Customer". and a button named "Add". Now I want every time "Add" is clicked, compiler take what is in my textfield and make an object of the class "Customer" named with what it took from the textfield. — First R0cRid3r
– First R0cRid3r, Commented Nov 24, 2012 at 22:40
@jlordo How so? Each Add should create a new customer and allow it to be listed, deleted, etc, no? Thus to say that Jonathan's answer is correct leaves out a very important aspect. — user166390
– user166390, Commented Nov 24, 2012 at 22:46

jlordo · Accepted Answer · 2012-11-24 22:29:11Z

2

Variable names must be determined at compile time, they are not even part of the generated code. So there is no way to do that.

If you want to be able to give your objects names, you can use

Map<String, MyClass> map = new HashMap<>();

Add objects to the map like this (e.g):

map.put(userInput, new MyClass());

and retrieve objects like this:

MyClass mc = map.get(userInput);

answered Nov 24, 2012 at 22:29

jlordo

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1 Comment

user166390 Over a year ago

I suspect the "ideal approach" would be to a combination of a List collection and state in the MyClass (e.g. "Customer Name") ..

Jon Newmuis · Accepted Answer · 2012-11-25 00:54:57Z

1

I'm not entirely sure what you mean by...

how can I just make a method to create a new object of my specified class just with a different name each time I call it

...but if I'm interpreting you correctly, I believe what you're trying to do as make MyClass accept a constructor parameter. You can do:

public class MyClass {
    private String name;

    public MyClass(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

Then to create a new instance of MyClass, do:

String name = jTextField0.getText();
MyClass instance = new MyClass(name);
instance.getName(); // returns the name it was given

EDIT

Since you've added clarifications in the comments since I first answered this question, I thought I would update the answer to portray more of the functionality that you're looking for.

To keep track of the MyClass instances, you can add them to an ArrayList. ArrayList objects can be instantiated as follows:

ArrayList<MyClass> customers = new ArrayList<MyClass>();

Then for each MyClass instance you wish to add, do the following:

customers.add(instance);

Note that the ArrayList should not be reinstantiated for each instance that you wish to add; you should only instantiate the ArrayList once.

edited Nov 25, 2012 at 0:54

answered Nov 24, 2012 at 22:28

Jon Newmuis

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6 Comments

First R0cRid3r Over a year ago

Thanks a lot for your response, I did what you said, and now I'm wondering if I have to make an array to keep the objects it makes? I mean I wrote that and I was expecting to see new objects in my code but it didn't happen so I thought maybe I'm too naive to think that way.

Jon Newmuis Over a year ago

You can keep track of them in an array, but it would likely be better to use a List. Since you have provided quite a bit more information since I first answered your question, I have edited my answer to account for this. Please see the answer above to see how to use an ArrayList to manage your MyClass references.

Matt Over a year ago

Since the size of your array would be dynamic, it's best to use a List instance (as suggested). Using an array in that case would be quite cumbersome. Don't forget to accept an answer as well, by clicking the little checkmark near it.

First R0cRid3r Over a year ago

I'm stuck so bad. I suppose my problem is that I didn't "understand" what you did and only tried to copy it. This is what I wrote: private void AddB0MouseClicked(java.awt.event.MouseEvent evt) { String name = NameT0.getText(); Customer instance = new Customer(Name); Customer.customers.add(instance); and this is my Customer class: public class Customer{ String name; public Customer(String name){ this.name = name; } public String getName(){ return name; } static ArrayList<Customer> customers = new ArrayList<Customer>();

First R0cRid3r Over a year ago

Thank you very much for the help :) Today I went to our university and asked our programming professor about the solution you gave me and he totally explained them to me. My main problem was that I didn't have a good understanding of arrays and array lists. It worked totally great. Thanks again

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