依賴

    def paging_version = "2.1.2"
    implementation "androidx.paging:paging-runtime:$paging_version" // For Kotlin use paging-runtime-ktx
    // alternatively - without Android dependencies for testing
    testImplementation "androidx.paging:paging-common:$paging_version" // For Kotlin use paging-common-ktx

在Room的基礎(chǔ)上：

• 1.數(shù)據(jù)庫取出數(shù)據(jù)方法(Dao)：

    @Query("SELECT * FROM WORD ORDER BY ID DESC")
    DataSource.Factory<Integer,Word> getAllWords();

• 2.LiveData的獲得方式：

        allWordsPagedListLive = new LivePagedListBuilder<>(wordDao.getAllWords(), 2).build(); // 2為一次讀取的數(shù)據(jù)數(shù)量

• 3.Adapter: 繼承PagedListAdapter

public class MyPagedAdapter extends PagedListAdapter<Word, MyPagedAdapter.MyViewHolder> {


    protected MyPagedAdapter() {
        super(new DiffUtil.ItemCallback<Word>() {
            @Override
            public boolean areItemsTheSame(@NonNull Word oldItem, @NonNull Word newItem) {
                return oldItem.getId() == newItem.getId();
            }

            @Override
            public boolean areContentsTheSame(@NonNull Word oldItem, @NonNull Word newItem) {
                return oldItem.getWord().equals(newItem.getWord());
            }
        });
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View view = inflater.inflate(R.layout.cell_card2,parent,false);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        Word word = getItem(position);
        if (word == null){
            holder.tvE.setText("loadingddddddddddddddd");
            Log.i("nanmu","null");
        }else {
            holder.tvNum.setText(String.valueOf(position + 1));
            holder.tvE.setText(word.getWord());
//            holder.tvC.setText(word.getTranslate());
        }
    }


    static class MyViewHolder extends RecyclerView.ViewHolder{
        TextView tvNum, tvC, tvE;
        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            tvNum = itemView.findViewById(R.id.tv_num);
            tvC = itemView.findViewById(R.id.tv_c);
            tvE = itemView.findViewById(R.id.tv_e);

        }
    }
}

• 4.更新方式：可選加回調(diào)

      allWordsPagedListLive.observe(this, new Observer<PagedList<Word>>() {
            @Override
            public void onChanged(final PagedList<Word> words) {
                adapter.submitList(words);
                words.addWeakCallback(null, new PagedList.Callback() {
                    @Override
                    public void onChanged(int position, int count) {
                        Log.d("mylog",String.valueOf(words));
                    }

                    @Override
                    public void onInserted(int position, int count) {

                    }

                    @Override
                    public void onRemoved(int position, int count) {

                    }
                });
            }
        });