Builder Design Pattern using Java Generics.

Foo.java

/*
 * Copyright 2016 Elmar Rhex Gomez.
 *
 * 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 com.example;

public class Foo extends Request {

    public void customPrint(){
        System.out.println("Foo");
    }

    public static class Builder extends Request.Builder<Foo, Builder> {


        public Builder() {
            super(Foo.class);
        }

        @Override
        public Foo build() {
            Foo c = getMainCLass();
            return c;
        }
    }

}

MainClass.java

/*
 * Copyright 2016 Elmar Rhex Gomez.
 *
 * 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 com.example;

public class MainClass {

    public static void main(String[] args) {

        Foo f = new Foo.Builder()
                .name("elmar")
                .last("gomez")
                .build();

        f.print();
        f.customPrint();

    }

}

Request.java

/*
 * Copyright 2016 Elmar Rhex Gomez.
 *
 * 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 com.example;

public class Request {

    String name;
    String lname;

    public void name(String name) {
        this.name = name;
    }

    public void last(String name) {
        this.lname = name;
    }

    public void print() {
        System.out.println(name);
        System.out.println(lname);
    }

    public abstract static class Builder<T extends Request, T1> {

        T gen;

        public Builder(Class<T> clazz) {

            try {
                gen = clazz.newInstance();
            } catch (InstantiationException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }

        }

        protected T getMainCLass() {
            return gen;
        }

        public T1 name(String name) {
            this.gen.name(name);
            return (T1) this;
        }

        public T1 last(String name) {
            this.gen.last(name);
            return (T1) this;
        }

        public abstract T build();

    }
}