Java – error: unable to determine the type parameter of T during Maven installation

I have this feature that throws strange errors when I try to do an "MVN installation"

public <T> T get(final AN_ENUM key)
{
    return some_map.get(key);
}

This is the wrong line I got

final int value = get(AN_ENUM.A_FIELD);

This is an error in Maven:

XXX.java:[25,41] type parameters of <T>T cannot be determined; 
  no unique maximal instance exists for type variable T with 
  upper bounds int,java.lang.Object

I already know how to "fix" I just need to change int to integer in the last code example and the error disappears It tells me that maven, for some reason, when I use type parameters, I can't take integers as int

My question is... Why?

During the eclipse, using the same JDK, I have been able to run my application without any kind of trouble or warning

>JDK 1.6 eclipse indigo service version 2 > Maven 3.0 four

Solution

In your POM XML, set the target version to at least 1.5:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>2.0.2</version>
    <configuration>
        <source>1.5</source>
        <target>1.5</target>
    </configuration>
</plugin>

In this way, Maven will use JDK 1.5 (you can set it to 1.6 if necessary)