AbstractBuilder.java

package com.example;

public abstract class AbstractBuilder<T> {

    protected T mObject;

    public AbstractBuilder() {
        // Type parameter 'T' cannot be instantiated directly
        mObject = new T();
    }

    public AbstractBuilder(T object) throws IllegalArgumentException {
        if (object == null) {
            throw new IllegalArgumentException("'object' cannot be null");
        }
        mObject = object;
    }

    public abstract T build();

}

Person.java

package com.example;

import java.util.Date;

public final class Person {

    private String mName;
    private Date mDateOfBirth;
    private String mGender;

    Person() {}

    public String getName() {
        return mName;
    }

    public Date getDateOfBirth() {
        return mDateOfBirth;
    }

    public String getGender() {
        return mGender;
    }

    public final static class Builder extends AbstractBuilder<Person> {

        public Builder() {
            super();
        }

        public Builder(final Person object) throws IllegalArgumentException {
            super(object);
        }

        @Override
        public Person build() {
            return mObject;
        }

        public Builder name(final String name) {
            mObject.mName = name;
            return this;
        }

        public Builder dateOfBirth(final Date dateOfBirth) {
            mObject.mDateOfBirth = dateOfBirth;
            return this;
        }

        public Builder gender(final String gender) {
            mObject.mGender = gender;
            return this;
        }
    }
}

Usage.java

package com.example;

import java.util.Calendar;
import java.util.GregorianCalendar;

public class Usage {

    void usage() {
        final Person avery = new Person.Builder()
                .name("Avery")
                .dateOfBirth(new GregorianCalendar(1987, Calendar.SEPTEMBER, 24).getTime())
                .gender(null)
                .build();
    }
}