CODEWITHSUNDEEP
javaeclipsegenericsnetbeansjavac
Stelios Adamantidis
Stelios Adamantidis

Reputation: 2031

Same code on same JDK compiles on Eclipse but causes inconvertible types on Netbeans, IDEA or command line

Code snippet is this:

package test;

import java.util.Collection;
import java.util.LinkedList;
import java.util.concurrent.*;

public class Test {

    public static void main(String[] args) {

        Callable<?> callable;
        final ExecutorService someExecutor = null;
        Collection<Callable<?>> tasks = new LinkedList<Callable<?>>();
        int timeoutInSeconds = 10;
        try {
            for (Future<?> f : someExecutor.invokeAll(
                    (Collection<? extends Callable<Callable<?>>>) tasks,
                    timeoutInSeconds, TimeUnit.SECONDS)) {
                f.get();
            }

        } catch (java.util.concurrent.CancellationException e) {

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

When I compile from command line

javac Test.java

I get the following error:

Test.java:17: inconvertible types
found   : java.util.Collection<java.util.concurrent.Callable<?>>
required: java.util.Collection<? extends java.util.concurrent.Callable<java.util.concurrent.Callable<?>>>
                (Collection<? extends Callable<Callable<?>>>) tasks,
                                                              ^

I also get the same error when I compile with IDEA or Netbeans. But eclipse thinks everythink is ok and runs normally. I triple checked that all 3 use the same JDK (1.6u45). So what does eclipse do differently?

Upvotes: 0

Views: 128

Answers (2)

Haixun Lu
Haixun Lu

Reputation: 40

If you specify the JVM with -vm option in your eclipse.ini, does eclipse has the same behavior? This doesn't work.

Try navigate to Preferences->Java->Compiler->Error/Warnings, in the right panel, search "Unchecked generic type operation", set level from "Ignored" to "Error". Have a rebuilt, you will get the same result.

Upvotes: 0

wero
wero

Reputation: 33000

Eclipse uses an own Java compiler ECJ which sometimes behaves differently than javac.

Upvotes: 1

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