CODEWITHSUNDEEP
javajar
Exploring
Exploring

Reputation: 3359

Same class is in multiple jar

I have several jars containing the exact same class.

Lets say for example, A.jar and B.jar have the same class Hello.class. What will happen if I run the following:

java -classpath A.jar;B.jar com.testing.testcode

My question is whether it will run or not? As from my understanding class loader will scan the classpath and it will return whatever Hello.class it finds first.

I know I can avoid this problem if I use OSGi for loading a particular class.

But what my question is – whether this will run or not? Or the java -classpath A.jar;B.jar com.testing.testcode will break down for having two version of the same class.

Upvotes: 0

Views: 3747

Answers (3)

Rupesh
Rupesh

Reputation: 2667

Whenever you include the jar in your classpath, on startup/ on application class gets loaded into the container.

Now whether your code will work or not will depend on which jar gets loaded first in your container and accordingly if you are lucky then in your current setup it will work else you might get some error saying that method1 doesn't accept Type1 it should accept Type2.

Upvotes: 0

Peter Lawrey
Peter Lawrey

Reputation: 533472

The class path is a "path". The first match is taken.

There is a boot class path which is examined first and this included the JARs in the JRE. BTW You can prepend these and override system classes but you are not supposed to and it might not be allowed in your license agreement.

Upvotes: 0

Frederic Close
Frederic Close

Reputation: 9639

This will work and the first Hello class in the classpath will be used, so in this case, the one from the A.jar

Upvotes: 4

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