title: What happened to Java Binary Compatibility?
body: <p>I came across an old set of classes dated March 1997. It was during the time when I tried to learn Java, and it was JDK 1.0.2</p>
  
  <p>Interestingly enough, I have both the source files and the class files intact from that time. The sources still compiles and executes as expected, which was really cool. But wasn't Java supposed to retain binary compatibility as well? Well, somewhere along the way, the format no longer holds valid.
  A Java 8 VM will report;</p>
  
  <pre><code>Exception in thread "main" java.lang.ClassFormatError: Invalid start_pc 65535 in LocalVariableTable in class file bali/core/Application
      at java.lang.ClassLoader.defineClass1(Native Method)
      at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
      at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
      at java.net.URLClassLoader.defineClass(URLClassLoader.java:455)
      at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
      :
      [snip many ClassLoader calls]
      :
      at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
      at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:495)
  </code></pre>
  
  <p>The offending class is the superclass of the class that I call from command line.</p>
  
  <p>One more detail, in those days, Microsoft was still in the Java camp, and I remember that their javac was more compliant against badly written syntax. The Sun compiler would gladly accept "public synchronized class Abc" and many other invalid statements. So, there is a big chance that these class files were generated by the MS compiler, and was then run on Sun JVM.</p>
  
  <p>Anyway, my question is; Is there anyone around who has knowledge about the compatibility commitment in the early versions of Java? Was it a big deal, or was it sacrificed on purpose? Or was there a decision much later, say Java 1.4 or Java 5 to simply drop JDK 1.0 support??</p>