Came accross this today and spent ages trying to reproduce/figure out what was happening. Can somebody explain why this happens or is this a bug with type erasure/default methods/lambda's/polymorphism? Uncommenting the default method makes it run fine, but I would have expected this to work as is
Output:
Works fine with an object
Calling consume
Hello
Calling accept with context
Hello
Calling accept via consumer...
Exception in thread "main" java.lang.AbstractMethodError: Method test/LambdaTest$$Lambda$1.accept(Ljava/lang/Object;)V is abstract
at test.LambdaTest$$Lambda$1/834600351.accept(Unknown Source)
at test.LambdaTest.main(LambdaTest.java:24)
Code
package test;
import java.util.function.Consumer;
public class LambdaTest {
public static void main(String[] args) {
Consumer<Context> contextIgnoringObject = new ContextUnawareObject();
contextIgnoringObject.accept(new Context());
ContextIgnorer contextIgnoringLambda = () -> {
System.err.println("Hello");
};
System.err.println("Calling consume");
contextIgnoringLambda.consume();
System.err.println("Calling accept with context");
contextIgnoringLambda.accept(new Context());
Consumer<Context> consumer = contextIgnoringLambda;
System.err.println("Calling accept via consumer...");
consumer.accept(new Context());
}
@FunctionalInterface
public interface ContextIgnorer extends Consumer<Context> {
// default void accept(Object object) {
// System.err.println("Manual bridge method");
// accept((Context)object);
// }
@Override
default void accept(Context context) {
consume();
}
void consume();
}
public static class ContextUnawareObject implements ContextIgnorer {
@Override
public void consume() {
System.err.println("Works fine with an object");
}
}
public static class Context {
}
}
