Question

I have a code like this:

protected <T> T doSomething(String someParam, Class<T> clazz) {
...
}

which I use in a TestCase class:

Class clazz = MyClass.class;
MyClass MyClass = someObject.doSomething(someString, clazz);

This code gives a warning in eclipse:

Class is a raw type. References to generic type Class should be parameterized

and

Multiple markers at this line
– Type safety: Unchecked invocation doSomething(String, Class) of the generic method doSomething(String, Class) of type MyClass
– Type safety: The expression of type Class needs unchecked conversion to conform to Class

When I run this code (test) in eclipse – everything works perfectly. When I do it through “mvn clean install” through command prompt, I get:

C:\pathToProject\src\test\java\packagesPath\MyTestCase.java:[xx,xxx] incompatible types found :
java.lang.Object
required: com.somePackagePath.MyClass

But when providing:

Class<MyClass> clazz = MyClass.class;
MyClass MyClass = someObject.doSomething(someString, clazz);

I don’t get any errors nor warnings. .
I understand that java compiler erases type info, so:
Shouldn’t eclipse provide a compiler error instead of warning, or is it the maven-plugin-compiler that creates the problem?
The maven plugin is:

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.6</source>
                <target>1.6</target>
                <showDeprecation>false</showDeprecation>
                <debug>true</debug>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>

Kind Regards,
Despot

Answer 1

This is a known bug in Eclipse: 333011: [compiler][1.5] Eclipse compiles codes which javac rejects: incompatible types . Feel free to vote for the bug and add your use case to it.

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There are situations when javac and Eclipse disagree, and you should report them as bugs. It is preferred to have a standalone test case of as few Java files as possible which can be copy/pasted in Eclipse and compiled using javac from the command line without any dependencies.