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ProductAdapter.java

/*
 * Copyright 2017, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.persistence.ui;

import android.databinding.DataBindingUtil;
import android.support.annotation.Nullable;
import android.support.v7.util.DiffUtil;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.ViewGroup;

import com.example.android.persistence.databinding.ProductItemBinding;
import com.example.android.persistence.model.Product;
import com.example.android.persistence.R;

import java.util.List;
import java.util.Objects;

public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {

List<? extends Product> mProductList;

@Nullable
    private final ProductClickCallback mProductClickCallback;

public ProductAdapter(@Nullable ProductClickCallback clickCallback) {
        mProductClickCallback = clickCallback;
    }

public void setProductList(final List<? extends Product> productList) {
        if (mProductList == null) {
            mProductList = productList;
            notifyItemRangeInserted(0, productList.size());
        } else {
            DiffUtil.DiffResult result = DiffUtil.calculateDiff(new DiffUtil.Callback() {
                @Override
                public int getOldListSize() {
                    return mProductList.size();
                }

@Override
                public int getNewListSize() {
                    return productList.size();
                }

@Override
                public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
                    return mProductList.get(oldItemPosition).getId() ==
                            productList.get(newItemPosition).getId();
                }

@Override
                public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
                    Product newProduct = productList.get(newItemPosition);
                    Product oldProduct = mProductList.get(oldItemPosition);
                    return newProduct.getId() == oldProduct.getId()
                            && Objects.equals(newProduct.getDescription(), oldProduct.getDescription())
                            && Objects.equals(newProduct.getName(), oldProduct.getName())
                            && newProduct.getPrice() == oldProduct.getPrice();
                }
            });
            mProductList = productList;
            result.dispatchUpdatesTo(this);
        }
    }

@Override
    public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        ProductItemBinding binding = DataBindingUtil
                .inflate(LayoutInflater.from(parent.getContext()), R.layout.product_item,
                        parent, false);
        binding.setCallback(mProductClickCallback);
        return new ProductViewHolder(binding);
    }

@Override
    public void onBindViewHolder(ProductViewHolder holder, int position) {
        holder.binding.setProduct(mProductList.get(position));
        holder.binding.executePendingBindings();
    }

@Override
    public int getItemCount() {
        return mProductList == null ? 0 : mProductList.size();
    }

static class ProductViewHolder extends RecyclerView.ViewHolder {

final ProductItemBinding binding;

public ProductViewHolder(ProductItemBinding binding) {
            super(binding.getRoot());
            this.binding = binding;
        }
    }
}