If you’re using the Mpowerlayer SDK for your J2ME development on Mac OS X, and you get the following ant build error:

  $ ant
  Buildfile: build.xml
  
  compile:
  
  preverify:
       [exec] Error preverifying class java.lang.Class
       [exec]     VERIFIER ERROR java/lang/Class.newInstance0()Ljava/lang/Object;:
       [exec] Illegal type in constant pool
       [exec] Result: 1
  
  package:
  
  BUILD SUCCESSFUL
  Total time: 1 second

Then you can fix it by changing the following entry in your build.xml:

<property name="java.classes.jar"  value="/System/Library/Frameworks/JavaVM.framework/Classes/classes.jar" />

to

 <property name="java.classes.jar" value="/System/Library/Frameworks/JavaVM.framework/Versions/1.4.2/Classes/classes.jar" />

The error seems to lie in the Java 1.5+ classes that are included in the original build.xml. The fix points the build file to the Java 1.4.2 classes that are also conveniently installed by default on Mac OS X.

Tags: j2me