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Re: UIDefaults key?

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On 8/6/2014 4:00 PM, Knute Johnson wrote:
> 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.

     ... which (as I failed to notice), is `protected'.  Also, it's
not a ComponentUI method, but a method that some (most?) subclasses
happen to provide, independently of each other.

> 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());
>              }
>          });
>      }
> }

     Here's a horrible hack that works for me, but it looks awfully
shaky (and shakily awful):

import java.awt.*;
import java.awt.event.*;
import java.awt.event.*;
import java.lang.reflect.*;
import java.util.logging.Level;
import javax.swing.*;
import javax.swing.*;
import javax.swing.plaf.*;
import javax.swing.plaf.*;
import javax.swing.plaf.basic.*;

public class test10 {

    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());

             Method method = findIt(clazz);
             System.out.println(method.getName());
             method.setAccessible(true);

             try {
                Constructor ctor = clazz.getConstructor(null);
                System.out.println(ctor.getName());
                ComponentUI instance = (ComponentUI) ctor.newInstance(null);
                System.out.println(instance);
                String prefix = (String) method.invoke(instance, null);
                System.out.println("prefix = \"" + prefix + "\"! Huzzah!");
             } catch (Exception ex) {
                ex.printStackTrace();
             }
          }
       });
    }

    private static Method findIt(Class<?> clazz) {
       while (ComponentUI.class.isAssignableFrom(clazz)) {
          for (Method meth : clazz.getDeclaredMethods()) {
             if (meth.getName().equals("getPropertyPrefix")) {
                return meth;
             }
          }
          clazz = clazz.getSuperclass();
       }
       throw new IllegalStateException("no getPropertyPrefix!");
    }
}

     Filthy and fragile, no?

     Hmmm: If you're looking for the default background of a JDoodad in
the prevailing look and feel, how about constructing a JDoodad, doing
nothing special to it, and calling getBackground()?

-- 
esosman@comcast-dot-net.invalid

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Thread

UIDefaults key? Knute Johnson <eternal@knutejohnson.com> - 2014-08-06 09:25 -0700
  Re: UIDefaults key? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-06 13:31 -0400
    Re: UIDefaults key? Knute Johnson <eternal@knutejohnson.com> - 2014-08-06 11:17 -0700
      Re: UIDefaults key? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-06 14:38 -0400
        Re: UIDefaults key? Knute Johnson <eternal@knutejohnson.com> - 2014-08-06 13:00 -0700
          Re: UIDefaults key? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-06 16:52 -0400

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