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From "Regis Xu (JIRA)" <j...@apache.org>
Subject [jira] Resolved: (HARMONY-6237) [classlib][luni] HashMap doesn't support proxy object as keys
Date Thu, 18 Jun 2009 11:05:07 GMT

     [ https://issues.apache.org/jira/browse/HARMONY-6237?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Regis Xu resolved HARMONY-6237.
-------------------------------

    Resolution: Fixed

Thanks Jim.

Patch applied at r786015, please verify.

> [classlib][luni] HashMap doesn't support proxy object as keys
> -------------------------------------------------------------
>
>                 Key: HARMONY-6237
>                 URL: https://issues.apache.org/jira/browse/HARMONY-6237
>             Project: Harmony
>          Issue Type: Bug
>          Components: Classlib
>    Affects Versions: 5.0M10
>            Reporter: Jim Yu
>            Assignee: Regis Xu
>             Fix For: 5.0M11
>
>         Attachments: HARMONY-6237.diff
>
>   Original Estimate: 48h
>  Remaining Estimate: 48h
>
> There is an interesting edge case in HashMap. If we use a proxy object as the key to
put something into HashMap, we will fail to retrieve the value by using that key. But RI works
well for this case. Here is a test case below to present the problem. I found the root cause
of the failure for Harmony HashMap is that proxyInstance.equals(proxyInstance) returns false
which sounds strange but appears work correctly as both Harmony and RI behave so. I suspect
RI has made some special approaches to match the key when the key is a proxy object. So I
would be inclined to follow RI's behavior in this case. 
> public interface MockInterface {
>     public String mockMethod();
> }
> public class MockClass implements MockInterface {
>     public String mockMethod() {
>         return "This is a mock class.";
>     }
> }
> import java.lang.reflect.InvocationHandler;
> import java.lang.reflect.Method;
> import java.lang.reflect.Proxy;
> import java.util.HashMap;
> import java.util.Map;
> public class TestProxy implements InvocationHandler {
>     Object obj;
>     public TestProxy(Object o) {
>         obj = o;
>     }
>     public Object invoke(Object proxy, Method m, Object[] args)
>             throws Throwable {
>         Object result = null;
>         try {
>             result = m.invoke(obj, args);
>         } catch (Exception e) {
>             e.printStackTrace();
>         } finally {
>         }
>         return result;
>     }
>     public static void main(String[] argv) throws Exception {
>         MockInterface proxyInstance = (MockInterface) Proxy.newProxyInstance(
>                 MockInterface.class.getClassLoader(),
>                 new Class[] { MockInterface.class }, new TestProxy(
>                         new MockClass()));
>         Map hm = new HashMap();
>         hm.put(proxyInstance, "Value");
>         Object o = hm.get(proxyInstance);
>         System.out.println("Value got for proxy object key:" + o);
>         System.out.println(proxyInstance.equals(proxyInstance));
>     }
> }
> Output
> Harmony:
> Value got for proxy object key:null
> false
> RI:
> Value got for proxy object key:Value
> false

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