FULL PRODUCT VERSION :
javac 1.6.0_16

java version "1.6.0_16"
Java(TM) SE Runtime Environment (build 1.6.0_16-b01)
Java HotSpot(TM) Client VM (build 14.2-b01, mixed mode, sharing)

java version "1.5.0_21"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_21-b01)
Java HotSpot(TM) Client VM (build 1.5.0_21-b01, mixed mode, sharing)

(Mac OS X 10.6)
java version "1.6.0_15"
Java(TM) SE Runtime Environment (build 1.6.0_15-b03-219)
Java HotSpot(TM) 64-Bit Server VM (build 14.1-b02-90, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.0.6002]

Darwin dn0a16674e.sunet 10.0.0 Darwin Kernel Version 10.0.0: Fri Jul 31 22:47:34 PDT 2009; root:xnu-1456.1.25~1/RELEASE_I386 i386

A DESCRIPTION OF THE PROBLEM :
Java 5 executes just fine [no thrown exceptions] when instantiating a class [that extends
java.awt.Component] even if it contains a method that returns an interface class [in the
same package], as long as that method is not invoked.

On the other hand, Java 6 throws a NoClassDefFoundError.

Did not look into whether the return type is an interface is a factor, nor if a constructor
other than the no-argument is used.

Works in 1.4.2.

What.class extending javax.swing.JFrame or java.awt.Frame gives the same result.

If What.class extends java.util.Properties instead, both Java 5 and Java 6 produce
the expected result.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Compile What.java and SomeInterface.java:

    javac -target 1.4 -source 1.4 What.java SomeInterface.java

2. Remove SomeInterface.class.

3. Using 1.5.0:

   java -cp . What

produces expected result. (No exception thrown.)

4. Using 1.6.0:

  java -cp . What

produces actual result. (Exception thrown.)


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
BEFORE new What()
 AFTER new What()

ACTUAL -
BEFORE new What()
Exception in thread "main" java.lang.NoClassDefFoundError: SomeInterface
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Class.java:2427)
        at java.lang.Class.getDeclaredMethod(Class.java:1935)
        at java.awt.Component.isCoalesceEventsOverriden(Component.java:5948)
        at java.awt.Component.access$500(Component.java:169)
        at java.awt.Component$3.run(Component.java:5902)
        at java.awt.Component$3.run(Component.java:5900)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.awt.Component.checkCoalescing(Component.java:5899)
        at java.awt.Component.<init>(Component.java:5868)
        at What.<init>(What.java:1)
        at What.main(What.java:5)
Caused by: java.lang.ClassNotFoundException: SomeInterface
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
        ... 12 more


ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.NoClassDefFoundError: SomeInterface
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Class.java:2427)
        at java.lang.Class.getDeclaredMethod(Class.java:1935)
        at java.awt.Component.isCoalesceEventsOverriden(Component.java:5948)
        at java.awt.Component.access$500(Component.java:169)
        at java.awt.Component$3.run(Component.java:5902)
        at java.awt.Component$3.run(Component.java:5900)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.awt.Component.checkCoalescing(Component.java:5899)
        at java.awt.Component.<init>(Component.java:5868)
        at What.<init>(What.java:1)
        at What.main(What.java:5)
Caused by: java.lang.ClassNotFoundException: SomeInterface
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
        ... 12 more


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
What.java:

public class What extends java.awt.Component {
  public SomeInterface returnSomeInterface() { return null; }
  public static void main(String[] args) {
    System.out.println("BEFORE new What()");
    new What();
    System.out.println(" AFTER new What()");
  }
}


SomeInterface.java:

interface SomeInterface {
}

---------- END SOURCE ----------

Release Regression From : 5.0u18
The above release value was the last known release where this
bug was not reproducible. Since then there has been a regression.