Parent.java and Child.java - compiled Ok.
Parent.class and Child.java - produces an error.

--- avl@everest [~/test_java]
cat Parent.java

public class Parent < T, B, C > {

    abstract public class Parent_inner {

        abstract protected void foo_1 ( T p1, B p2, C p3 );

        abstract protected void foo_2 ( T p1, B p2, C p3 );
    }

    abstract public class Parent_inner_impl extends Parent_inner {
        protected void foo_1 ( T p1, B p2, C p3 ) {
            System.out.println("Prent_inner_impl foo_1");
        }
    }
}


--- avl@everest [~/test_java]
cat Child.java

public class Child extends Parent<String, Integer, Integer > {

    public static void main(String args[]) {

        Child cur_child = new Child();
        Parent_inner test = cur_child.new Parent_inner_impl () {
            protected void foo_2 ( String p1, Integer p2, Integer p3 ) {
                System.out.println("Parent_inner_impl foo_2");
            }
        };
   }
}
--- avl@everest [~/test_java]
javac Child.java Parent.java
--- avl@everest [~/test_java]
javac Parent.java
--- avl@everest [~/test_java]
javac Child.java
Child.java:8: <anonymous Child$1> is not abstract and does not override abstract method foo_2(java.lang.Object,java.lang.Object,java.lang.Object) in Parent.Parent_inner
            protected void foo_2 ( String p1, Integer p2, Integer p3 ) {
                           ^
Note: Child.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error
--- avl@everest [~/test_java]
java -version
java version "1.5.0_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_01-b08)
Java HotSpot(TM) Server VM (build 1.5.0_01-b08, mixed mode)
--- avl@everest [~/test_java]

method foo2 already implemented in anonimous class, but compiler say that it is not.