# Hello.java

    /*
     * Copyright (c) 2012, Niclas Hedhman. All Rights Reserved.
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     *
     */
    package org.qi4j.tutorials.hello;

    import org.qi4j.api.common.UseDefaults;
    import org.qi4j.api.injection.scope.This;
    import org.qi4j.api.mixin.Mixins;
    import org.qi4j.api.property.Property;
    import org.qi4j.library.constraints.annotation.NotEmpty;

    // START SNIPPET: body

    /**
     * This Composite interface declares a simple "Hello World" interface with a single say() method. What is being
     * said is defined in the HelloWorldState interface, which is a private mixin.
     */
    @Mixins( { Hello.HelloWorldMixin.class } )
    public interface Hello
    {
        String say();

        /**
         * This is the implementation of the say() method.
         */
        public abstract class HelloWorldMixin
            implements Hello
        {
            // @This reference the composite itself, and since HelloWorldState is not part of the public interface,
            // it is a private mixin.
            @This
            private State state;

            @Override
            public String say()
            {
                return state.phrase().get() + " " + state.name().get();
            }
        }

        /**
         * This interface contains only the state of the HelloWorld object.
         */
        public interface State
        {
            @NotEmpty
            @UseDefaults
            Property<String> phrase();

            @NotEmpty
            @UseDefaults
            Property<String> name();
        }
    }
    // END SNIPPET: body