Java开发场景多用一些其他更好好用的方法建议

1、集合实现类不一定只用ArrayList、LinkedList
（Vector比较老了就算了）、HashSet、TreeSet、LinkedHashSet、HashMap、TreeMap、LinkedHashMap都可以，特别是Tree开头的。生僻的Hashtable、ConcurrentHashMap也不是不能用
2、jdk 8 新特性能用就尽量用
Lambda
Stream流

if (null != studentMap) {
      studentMap.keySet().forEach(o -> {
        System.out.println("key = " + o + ", value = " + studentMap.get(o));
      });
    }

private Map<String, String> getGeoHashHeatMapDataMap(String categoryInfo) {
    List<KeyValueData> categoryList = JSONObject.parseArray(categoryInfo, KeyValueData.class);
    Map<String, String> map = categoryList.stream()
            .collect(Collectors.toMap(KeyValueData::getK, KeyValueData::getV));
    return map;
}

3、创建对象
反射
采用clone机制
通过序列化
用newInstance吧

//2 newInstance
    try {
      Class aClass = Class.forName("basice.Hello");
      Hello h2 = (Hello) aClass.newInstance();
      h2.sayWorld("newInstance");
    } catch (ClassNotFoundException e) {
      e.printStackTrace();
    } catch (IllegalAccessException e) {
      e.printStackTrace();
    } catch (InstantiationException e) {
      e.printStackTrace();
    }

4、数据结构与算法
排序

5、优化多余if else（表达式写法、case等）
电商公司枚举类如下：

package basice;

/**
 * @author kegekeqi
 * @version 1.0
 * @date 2021-12-19 17:32
 */
public enum EleCommerceEnum {

  TAOBAO(1, "淘宝"),
  PINGDUODUO(2, "拼多多");

  Integer id;
  String name;

  EleCommerceEnum(Integer id, String name) {
    this.id = id;
    this.name = name;
  }
}

if else的方式，如果电商平台越多，代码就越显得冗余：

换成switch case 精简了不少代码

;

/**
 * @author kegekeqi
 * @version 1.0
 * @date 2021-12-19 17:35
 */
public class EleCommerceMain {
  public Double count(EleCommerceEnum company, Integer weight) {
    switch (company) {
      case TAOBAO:
        System.out.println(10 + weight * 1.1);
        return 10 + weight * 1.1;
      case PINGDUODUO:
        System.out.println(6 + weight * 1.2);
        return 6 + weight * 1.2;
      default: throw new IllegalArgumentException("No Data");
    }
  }
  public static void main(String[] args) {
    Class aClass = null;
    try {
      aClass = Class.forName("basice.EleCommerceMain");
    } catch (ClassNotFoundException e) {
      e.printStackTrace();
    }
    EleCommerceMain h = null;
    try {
      h = (EleCommerceMain) aClass.newInstance();
    } catch (InstantiationException e) {
      e.printStackTrace();
    } catch (IllegalAccessException e) {
      e.printStackTrace();
    }
//    EleCommerceMain h = new EleCommerceMain();
    h.count(EleCommerceEnum.TAOBAO, 2);
  }
}