How to get instance of all components in a frame dynamically

> Hai ,

> I want to know how to get the instance

> names and values of components on a frame. if

> any body knows anything on this

> lease help me

> Advance Thanks

What names? The names of the instance variables in the source code?

What values? A component doesn't have 'a value'. Text components have some kind of text and other values. Buttons and labels have texts and icons. A custom component might have a custom value...

-Puce

Pucea at 2007-7-14 23:32:09 >

Hai Please......

i want to write a method it should accept the Frame object as a parameter .

this method print all the instance name and values of the component on that frame object

example:

Frame fobj=new Frame();

JTextField jTextField1=new JTextField(" ABCD ");

fobj.add(jTextField1);

...

..

.

.

.

Now i want that method to print

name = jTextField1 and its Value=ABCD

like this ....

If 'n' number of components are on that frame it should print all components instance names and values

Kondabathini_Naveena at 2007-7-14 23:32:09 >

> > JTextField jTextField1=new JTextField(" ABCD ");

> > Now i want that method to print

> > name = jTextField1 and its Value=ABCD

>

> Components don't have a "name". The name is used in

> your source program. Once the program is compiled,

> the computer doesn't care about the name you give it,

> its just an Object in memory. Have you ever looked in

> a class file? Do you see the variable names anywhere

> in the file?

Interesting! I've never looked at class files, but I thought you could get the instance variables with getClass().getDeclaredFields(). Then call getName() on the Field objects to get their names.

But this would work only for instance variables of course. If your components variables are just local variables in a method and then added to the Container, then this reflection approach wouldn't work.

Another technique, and maybe the better one:

Use the 'name' property of the components! I think that some GUI builders like NetBeans' Matisse set them automatically to the name of the instance method. Otherwise set them explicitly.

Then get all components from your container (something like getComponents()) and get their names with getName().

But for the value this is a little bit trickier as I mentioned above. There's no "value" property, since it depends on the type of the component.

If your just interested in the values of text fields, one approach could be to explicitly test the components with something like

if (comp instanceof JTextField){

}

But if you have control over the container, a better approach would be to make a List of JTextFields and then just iterate over that list, getting their names and values.

-Puce

Message was edited by:

Puce

Pucea at 2007-7-14 23:32:09 >

Hai

I had written my code like thisSolve my problem

// this means frame object

java.awt.Component[] components=this.getContentPane().getComponents();

if(components instanceof JTextField){

//getting the value in the text field

components.getText();

//gettting the name of the component

components.getName();

but here were not getting instance name

// we are getting instance names on components like this

but here we are not getting value

java.lang.reflect.Field[] _field;

_field=this.getClass().getDeclaredFields();

_field.getName();

}

Advance Thanks

Kondabathini_Naveena at 2007-7-14 23:32:09 >

> //gettting the name of the component

> components.getName();

As I said: If you're not using a GUI builder that sets the 'name' property to the name of the instance variable, you have to do it yourself:

myTextField1.setName("myTextField1");

So the best thing would be to use a GUI builder that synchronizes the 'name' property with the instance variable name. (I think NetBeans does that.)

-Puce

Message was edited by:

Puce

Pucea at 2007-7-14 23:32:10 >

Well, it seems that I was wrong, and NetBeans doesn't synchronize the name property :-(

Still you could set them manually (and maybe document this as a requirement).

Or use the reflection approach to get the names (instance variables only!)

Field[] fields = getClass().getDeclaredFields()

for (Field field : fields){

if (JTextField.class.isAssignableFrom(field.getType())){

string name = field.getName();

JTextField tf = (JTextField) field.get(this);

string value = tf.getText();

}

}

Note: I didn't test that code, but maybe it works with something like that.

-Puce

Message was edited by:

Puce

Pucea at 2007-7-14 23:32:10 >

> Thanks Pauce

> But we are not getting local

> varaibles .how to get when components added during

> runtime

Well, what name do you want when a component is added like this:

addComponent(new JTextField());

or like this:

for (int i=0; i<10; i++){

JTextField field = new JTextField();

addComponent(field);

}

?

This is neither possible using reflection (as I said: instance variables only) nor does it make much sense.

As I suggested before: Always set the name property (document this as a requirement).

-Puce

Pucea at 2007-7-14 23:32:10 >