Java Builder模式构建MAP/LIST的实例讲解

import java.util.HashMap;import java.util.Map; public class MapBuilder<T> {   public Builder<T> b;   public MapBuilder(Builder<T> b){  this.b = b; }   public Map<String,T> map(){  return b.map; }   public T get(String key){  return b.map.get(key); }  public static class Builder<T>{     public Map<String, T> map;     public Builder(){   map = new HashMap<String, T>();  }     public Builder<T> map(String key, T value){   map.put(key, value);   return this;  }        public MapBuilder<T> build(){   return new MapBuilder<T>(this);  } }   public static void main(String[] args) {  MapBuilder<String> build = new MapBuilder.Builder<String>().map("a", "b").build();  System.out.println(build.get("a")); }  }

public class ListBuilder<T> {   public Builder<T> b;   public ListBuilder(Builder<T> b){  this.b = b; }   public List<T> list(){  return b.list; }   public T get(int index){  return b.list.get(index); }  public static class Builder<T>{     public List<T> list;     public Builder(){   list = new ArrayList<T>();  }     public Builder<T> add(T value){   list.add(value);   return this;  }        public ListBuilder<T> build(){   return new ListBuilder<T>(this);  } }   public static void main(String[] args) {  ListBuilder<String> build = new ListBuilder.Builder<String>().add("a").add("b").build();  System.out.println(build.get(0)); }  }