Re: [cp-patches] FYI: MetalTabbedPaneUI fix

[Michael Koch]

On Fri, Apr 15, 2005 at 11:03:45AM +0200, Roman Kennke wrote:
> The following fix lets MetalTabbedPaneUI create one instance of itself 
> instead of sharing a singleton.
> 
> 2005-04-15  Roman Kennke  <address@hidden>
> 
>         * javax/swing/plaf/metal/MetalTabbedPaneUI.java
>         (createUI): Create one MetalTabbedPaneUI per Component instead
>         of sharing one instance.
> 
> 
> /Roman
> 

> Index: javax/swing/plaf/metal/MetalTabbedPaneUI.java
> ===================================================================
> RCS file: 
> /cvsroot/classpath/classpath/javax/swing/plaf/metal/MetalTabbedPaneUI.java,v
> retrieving revision 1.2
> diff -u -r1.2 MetalTabbedPaneUI.java
> --- javax/swing/plaf/metal/MetalTabbedPaneUI.java     14 Apr 2005 13:58:51 
> -0000      1.2
> +++ javax/swing/plaf/metal/MetalTabbedPaneUI.java     15 Apr 2005 09:00:03 
> -0000
> @@ -38,6 +38,8 @@
>  
>  package javax.swing.plaf.metal;
>  
> +import java.util.HashMap;
> +import java.util.Map;
>  import javax.swing.JComponent;
>  import javax.swing.plaf.ComponentUI;
>  import javax.swing.plaf.basic.BasicTabbedPaneUI;
> @@ -46,9 +48,8 @@
>    extends BasicTabbedPaneUI
>  {
>  
> -  // FIXME: maybe replace by a Map of instances when this becomes stateful
>    /** The shared UI instance for JTabbedPanes. */
> -  private static MetalTabbedPaneUI instance = null;
> +  private static Map instances = null;

As you know this will always contain a HashMap its better to make it a
HashMap as method calls to explicit classes is faster then calling
methods through interfaces. Speed doesnt really matter in this case but
this is a general rule.
  
>    /**
>     * Constructs a new instance of MetalTabbedPaneUI.
> @@ -67,8 +68,19 @@
>     */
>    public static ComponentUI createUI(JComponent component)
>    {
> -    if (instance == null)
> -      instance = new MetalTabbedPaneUI();
> +    if (instances == null)
> +      instances = new HashMap();
> +
> +    Object o = instances.get(component);
> +    MetalTabbedPaneUI instance;
> +    if (o == null)
> +      {
> +     instance = new MetalTabbedPaneUI();
> +     instances.put(component, instance);
> +      }
> +    else
> +      instance = (MetalTabbedPaneUI) o;
> +
>      return instance;
>    }
>  }

Michael
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