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Java Builder模式构建MAP/LIST

吓死我了_1799 2022-04-29 阅读 73
java
package com.ctid.util;

import java.util.HashMap;
import java.util.Map;

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"));
        Map<String, String> map = build.map();
        System.out.println(map.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));
 }
  
}
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