Java understand IncompatibleClassChangeError 2019-04-22 08:05
When I use thrift generate classes I got IncompatibleClassChangeError. This error means the class you depends has changed. Let's say your project depend on ClassA.class. When ClassA.class upgrades to new version (add some new methods or fields). It's name doesn't change. You project can use both old and new version of this class. This is "Binary Compatibility". But when the new version change one static field to no-static. IncompatibleClassChangeError will be thrown.
Let's generate IncompatibleClassChangeError. Prepare two class like following.
public class Test{
public static void main(String[] args){
DependClass depend = new DependClass();
System.out.println(depend.luck);
}
}
public class DependClass{
public static String luck="luck";
}
Compile both classes and you will get two class file
[root@localhost tmp]# javac Test.java
[root@localhost tmp]# javac DependClass.java
Run Test you will get the following output.
[root@localhost tmp]# java Test
luck
Change field luck to no-static.
public class DependClass{
public String luck="luck";
}
compile and run Test again.
[root@localhost tmp]# javac DependClass.java
[root@localhost tmp]# java Test
Exception in thread "main" java.lang.IncompatibleClassChangeError: Expected non-static field DependClass.luck
at Test.main(Test.java:4)
EOF