There is binary incompatibility problem between JDK1.2beta4G and 
JDK1.1.6.
The JDK1.2beta4G could not execute class compiled by JDK1.1.6 
that contains inner public class with private constructor.
It throws IllegalAccessError.


==== Here is the test demonstrating the bug ====
public class TestInner {

    public class InnerClassPublic {
    	public InnerClassPublic(){
    	}
    }
    public class InnerClassPrivate {
    	private InnerClassPrivate(){
    	}
    }
    public TestInner () {
    }
    public static void main(String[] args){
    	TestInner A = new TestInner();
    	InnerClassPublic B = A.a();
    	System.out.println("OKAY: InnerClassPublic created");
    	InnerClassPrivate C = A.b();
        System.out.println("OKAY: InnerClassPrivate created");
    }
    public InnerClassPublic a() {
    	return new InnerClassPublic();
    }
    public InnerClassPrivate b() {
    	return new InnerClassPrivate();
    }
}

==== Here is the output of the test ====

------- Under jdk1.1.6 ------- 
(  xxxxx@xxxxx  @/home/sda/temp/tests)71%/set/java/jdk1.1.6/solaris/bin/java -fullversion
java full version "JDK1.1.6N"
(  xxxxx@xxxxx  @/home/sda/temp/tests)72%/set/java/jdk1.1.6/solaris/bin/javac TestInner.java
(  xxxxx@xxxxx  @/home/sda/temp/tests)74%/set/java/jdk1.1.6/solaris/bin/java TestInner
OKAY: InnerClassPublic created
OKAY: InnerClassPrivate created

(  xxxxx@xxxxx  @/home/sda/temp/tests)70%java -fullversion
java full version "JDK-1.2beta4-G"
(  xxxxx@xxxxx  @/home/sda/temp/tests)75%java TestInner
OKAY: InnerClassPublic created
Exception in thread "main" java.lang.IllegalAccessError: try to access method TestInner$InnerClassPrivate.<init>(LTestInner;)V from class TestInner
	at TestInner.b(Compiled Code)
	at TestInner.main(Compiled Code)


------- Under jdk1.2-beta4-G ------- 
(  xxxxx@xxxxx  @/home/sda/temp/tests)104%java -fullversion
java full version "JDK-1.2beta4-G"
(  xxxxx@xxxxx  @/home/sda/temp/tests)105%javac TestInner.java
(  xxxxx@xxxxx  @/home/sda/temp/tests)106%java TestInner
OKAY: InnerClassPublic created
OKAY: InnerClassPrivate created

======================================================================
 Justification:
This is a compatibility-related bug

======================================================================

N/A

I am handing this off to   xxxxx@xxxxx  .  I suspect that this is not actually a bug, but the result of a bug from 1.1.6 being fixed in 1.2 combined with stronger access checking.

  xxxxx@xxxxx   1998-05-27

Versions of javac prior to 1.2beta4 did not generate an access method
for private constructors accessed from within another class.  The code
that was generated in this case would not pass the VM-level access checks.
These checks were suppressed for code loaded from the classpath in versions
of the VM prior to 1.2beta3, thus only code executed as an applet would fail.

This is documented behavior for 1.2 -- see "Runtime Incompatibilities in
Version 1.2" in http://java.sun.com/products/jdk/1.2/compatibility.html.

The workaround is to either recompile the code with 1.2beta4 or later, or to
turn off verification in the VM:  java -Xverify:none (or -Xverify:remote)

  xxxxx@xxxxx   1998-05-27