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From: Knute Johnson <eternal@knutejohnson.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: UIDefaults key?
Date: Wed, 06 Aug 2014 13:00:35 -0700
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On 8/6/2014 11:38, Eric Sosman wrote:
> On 8/6/2014 2:17 PM, Knute Johnson wrote:
>> On 8/6/2014 10:31, Eric Sosman wrote:
>>> On 8/6/2014 12:25 PM, Knute Johnson wrote:
>>>> JComponent has a method, getUIClassID(),  to return the UIDefaults key
>>>> for the ComponentUI subclass.  A JTextField returns a key of
>>>> TextFieldUI.  A typical subclass is
>>>> javax.swing.plaf.metal.MetalTextFieldUI.
>>>>
>>>> All the interesting details in the UIDefaults however use keys such as
>>>> TextField.foreground, TextField.border, TextField.margin etc.  Is there
>>>> any way to get the prefix, TextField, from the component other than
>>>> stripping the UI off the end of the UIClassID?
>>>
>>>      Climbing the class hierarchy from MetalTextFieldUI up to
>>> BasicTextFieldUI, I find the method
>>>
>>>      /**
>>>       * Fetches the name used as a key to lookup properties through the
>>>       * UIManager.  This is used as a prefix to all the standard
>>>       * text properties.
>>>       *
>>>       * @return the name ("TextField")
>>>       */
>>>      protected String getPropertyPrefix() {
>>>          return "TextField";
>>>      }
>>>
>>> ... which sort of looks like what you're after.  (But I haven't
>>> researched any other delegate classes, so it's possible they're
>>> different.)
>>>
>>
>> I think that is the answer Eric but I just not sure how to get there
>> from here yet :-).
>
>      Sorry: I somehow thought you already had your hands on an instance
> of the ComponentUI subclass -- But now I think you've got nothing but a
> JComponent object.  Also, I see that the method I stumbled upon is
> defined for some ComponentUI subclasses, but not for all.
>
>      Perhaps it's time to take a step back and think about the eventual
> goal rather than about one particular (and possibly unworkable) route
> toward it.  What problem are you trying to solve?
>

I'm trying to find one of the properties, ???.background, for several 
different components.  Currently, I get the UIClassID from the component 
and lop of the UI at the end and use that as a key to get the value from 
UIDefaults.  I was hoping to find a way to get the UIDefaults key 
directly from the JComponent but I'm not having much luck.

That method you found is the way to go but I don't know how to get 
there.  I've got the name of the class, I just need to create an 
instance and call the getPropertyPrefix() method.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.*;
import javax.swing.plaf.basic.*;

public class test9 {
     public static void main(String... args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 JTextField tf = new JTextField();
                 String key = tf.getUIClassID();
                 System.out.println(key);
                 UIDefaults defaults = UIManager.getDefaults();
                 Class<? extends ComponentUI> clazz = 
defaults.getUIClass(key);
                 System.out.println(clazz.getName());
             }
         });
     }
}

-- 

Knute Johnson