RecyclerView性能提升神器-DiffUtil（实用）

• 更多分享：www.catbro.cn

使用步骤：

定义数据bean

• 代码如下 public class DiffBean { private Long id; private String content;

      public Long getId() {
          return id;
      }
  
      public void setId(Long id) {
          this.id = id;
      }
  
      public String getContent() {
          return content;
      }
  
      public void setContent(String content) {
          this.content = content;
      }
   }
  

实现自己的回调函数

• 代码如下

  public class DiffCallBack extends DiffUtil.Callback {
      private List<DiffBean> mNewDatas,mOldDatas;
      public List<DiffBean> getNewDatas() {
          return mNewDatas;
      }
      public void setNewDatas(List<DiffBean> newDatas) {
          mNewDatas = newDatas;
      }
      public List<DiffBean> getOldDatas() {
          return mOldDatas;
      }
      public void setOldDatas(List<DiffBean> oldDatas) {
          mOldDatas = oldDatas;
      }
      @Override
      public int getOldListSize() {
          return mOldDatas==null?0:mOldDatas.size();
      }
      @Override
      public int getNewListSize() {
          return mNewDatas==null?0:mNewDatas.size();
      }
      @Override
      public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
          return mOldDatas.get(oldItemPosition).getId().equals(mNewDatas.get(newItemPosition).getId());
      }
  
      @Override
      public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
  
          return mOldDatas.get(oldItemPosition).getContent().equals(mNewDatas.get(newItemPosition).getContent());
      }
      @Nullable
      @Override
      public Object getChangePayload(int oldItemPosition, int newItemPosition) {
          DiffBean oldBean = mOldDatas.get(oldItemPosition);
          DiffBean newBean = mNewDatas.get(newItemPosition);
          //这里就不用比较核心字段了,一定相等
          Bundle payload = new Bundle();
          if (!oldBean.getContent().equals(newBean.getContent())) {
              payload.putString("KEY_CONTENT", newBean.getContent());
          }
          if (payload.size() == 0){
              return null;
              }
          return payload;
  }
  

• 重写适配器方法

  public Object getChangePayload(int oldItemPosition, int newItemPosition) {
          //高级用法，实现局部刷新
          // 定向刷新中的部分更新，重此没有白光一闪
          DiffBean oldBean = mOldDatas.get(oldItemPosition);
          DiffBean newBean = mNewDatas.get(newItemPosition);
          Bundle payload = new Bundle();
          if (!oldBean.getContent().equals(newBean.getContent())) {
              payload.putString("KEY_CONTENT", newBean.getContent());
          }
          if (payload.size() == 0)//如果没有变化 就传空
              return null;
          return payload;//
      }
  

• 代码如下

     List oldList = mAdapter.getData();
  DiffResult result = DiffUtil.calculateDiff(new MyCallback(oldList, newList));
   mAdapter.setData(newList);
  result.dispatchUpdatesTo(mAdapter);      
  

总结：

• 至此完工，代码量不多，推荐可以直接看下源码，喜欢就给我留言吧