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java.lang.ClassCastException with generic types

See original GitHub issue

Hi,

I’ve tried this:

@Test
public void test() {
    given(testCollectionSourceProvider.getCollection(new ArrayList<Integer>())).willReturn(new ArrayList<>());
}

static class TestCollectionSourceProvider {
    <T extends Collection<E>, E> T getCollection(T collection) {
        return collection;
    }
}

But I’ve got an Exception with a very confusing message in Idea 2017.1.5 and Eclipse Neon.3:

java.lang.ClassCastException: java.util.LinkedList cannot be cast to java.util.ArrayList
	at com.example.demo.FailingTestWithCollectionsTest.test(FailingTestWithCollectionsTest.java:24)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

But it works from Maven.

If I cast it manually, it works from IDEs:

given((List<Integer>) testCollectionSourceProvider.getCollection(new ArrayList<Integer>())).willReturn(new ArrayList<>());

Java versions:

machine

java version “1.8.0_144” Java™ SE Runtime Environment (build 1.8.0_144-b01) Java HotSpot™ 64-Bit Server VM (build 25.144-b01, mixed mode)

IntelliJ IDEA 2017.1.5 Build #IC-171.4694.70, built on July 4, 2017 JRE: 1.8.0_112-release-736-b21 amd64 JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o Windows 10 10.0

Apache Maven 3.5.0 (ff8f5e7444045639af65f6095c62210b5713f426; 2017-04-03T21:39:06+02:00) Maven home: C:\Maven Java version: 1.8.0_131, vendor: Oracle Corporation Java home: C:\Program Files\Java\jdk1.8\jre Default locale: en_US, platform encoding: Cp1252 OS name: “windows 10”, version: “10.0”, arch: “amd64”, family: “windows”

machine

java version “1.8.0_141” Java™ SE Runtime Environment (build 1.8.0_141-b01) Java HotSpot™ 64-Bit Server VM (build 25.141-b01, mixed mode)

Platform: Eclipse Neon.3 (4.6.3) Version: 3.9.0.RELEASE Build Id: 201707061903 Windows 7

Please check it: https://github.com/shark300/ClassNotFoundException-in-Mockito

Issue Analytics

State:
Created 6 years ago
Comments:15 (8 by maintainers)

Top GitHub Comments

1reaction

TimvdLippecommented, Oct 27, 2017

Yes I can reproduce this issue with the Eclipse compiler in IntelliJ. To enable the Eclipse compiler File -> Settings -> Build, Execution, Deployment -> Compiler -> Java Compiler -> Use compiler. Select Eclipse. Then recompile the test added in #1219 (ctrl + shift + F9) and then run the test.

0reactions

shark300commented, Nov 21, 2019

It’s still failing with openjdk 11.0.2, junit-jupiter 5.4, mockito 3.0. BTW, it cannot be fixed.

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