@Builder
public class Person {

	private String name;
	
	private int age;
	
	public static void main(String[] args) {
    
    	Person p = Person.builder().age(15).build();
   
	} 
}

//使用lombok注解的
import lombok.Builder;
import java.util.Set;

@Builder
public class BuilderExample {
   private String name;
   private int age;
   @Singular
   private Set<String> occupations;
}

import java.util.Set;
class BuilderExample {
    private String name;
    private int age;
    private Set<String> occupations;

    BuilderExample(String name, int age, Set<String> occupations) {
        this.name = name;
        this.age = age;
        this.occupations = occupations;
    }

    public static BuilderExampleBuilder builder() {
        return new BuilderExampleBuilder();
    }

    public static class BuilderExampleBuilder {
        private String name;
        private int age;
        private java.util.ArrayList<String> occupations;

        BuilderExampleBuilder() {
        }

        public BuilderExampleBuilder name(String name) {
            this.name = name;
            return this;
        }

        public BuilderExampleBuilder age(int age) {
            this.age = age;
            return this;
        }

        public BuilderExampleBuilder occupation(String occupation) {
            if (this.occupations == null) {
                this.occupations = new java.util.ArrayList<String>();
            }

            this.occupations.add(occupation);
            return this;
        }

        public BuilderExampleBuilder occupations(Collection<? extends String> occupations) {
            if (this.occupations == null) {
                this.occupations = new java.util.ArrayList<String>();
            }

            this.occupations.addAll(occupations);
            return this;
        }

        public BuilderExampleBuilder clearOccupations() {
            if (this.occupations != null) {
                this.occupations.clear();
            }

            return this;
        }

        public BuilderExample build() {
            // complicated switch statement to produce a compact properly sized immutable set omitted.
            // go to https://projectlombok.org/features/Singular-snippet.html to see it.
            Set<String> occupations = ...;
            return new BuilderExample(name, age, occupations);
        }

        @java.lang.Override
        public String toString() {
            return "BuilderExample.BuilderExampleBuilder(name = " + this.name + ", age = " + this.age + ", occupations = " + this.occupations + ")";
        }
    }
}

package com.stardust.effective.role1;

/**
 * Created by mike on 2017/12/3.
 * 它们有名称
 */
public class Fruit {

    private String color;

    private String size;

    private Fruit(String color,String size){
        this.color=color;
        this.size=size;
    }

    /**
     * 通过方法名可以知道要构造什么样的对象
     * @return
     */
    public static Fruit getBigGreenFruit(){
        return new Fruit("green","big");
    }

    public static Fruit getSmallRedFruit(){
        return new Fruit("red","small");
    }

    public static Fruit getApple(){
        return new Fruit("red","middle");
    }

}

/**
 * Returns an immutable list containing only the specified object.
 * The returned list is serializable.
 *
 * @param  <T> the class of the objects in the list
 * @param o the sole object to be stored in the returned list.
 * @return an immutable list containing only the specified object.
 * @since 1.3
 */
public static <T> List<T> singletonList(T o) {
    return new SingletonList<>(o);
}

/**
 * @serial include
 */
private static class SingletonList<E>
    extends AbstractList<E>
    implements RandomAccess, Serializable {

    private static final long serialVersionUID = 3093736618740652951L;

    private final E element;

    SingletonList(E obj)                {element = obj;}

    public Iterator<E> iterator() {
        return singletonIterator(element);
    }

    public int size()                   {return 1;}

    public boolean contains(Object obj) {return eq(obj, element);}

    public E get(int index) {
        if (index != 0)
          throw new IndexOutOfBoundsException("Index: "+index+", Size: 1");
        return element;
    }

    // Override default methods for Collection
    @Override
    public void forEach(Consumer<? super E> action) {
        action.accept(element);
    }
    @Override
    public boolean removeIf(Predicate<? super E> filter) {
        throw new UnsupportedOperationException();
    }
    @Override
    public void replaceAll(UnaryOperator<E> operator) {
        throw new UnsupportedOperationException();
    }
    @Override
    public void sort(Comparator<? super E> c) {
    }
    @Override
    public Spliterator<E> spliterator() {
        return singletonSpliterator(element);
    }
}

``` 

术语：基于接口的框架(interface-based framework)：框架的对外访问与接入渠道是基于接口实现的。

#### 在创建参数化类型实例的时候，使代码更加简洁

``` java
// 当前做法
Map<String, List<String>> map = new HashMap<String, List<String>>();
// 举例这样做会更简洁
Map<String, List<String>> map = HashMap.newInstance();
// java8已经可以直接这样写了
Map<String, List<String>> map = new HashMap<>();