Android开发—RecyclerView使用_安卓recyclerview

1.RecyclerView是什么

RecyclerView 在Android中用于创建列表。
官网的解释为： RecyclerView 可以让您轻松高效地显示大量数据。您提供数据并定义每个列表项的外观，而 RecyclerView 库会根据需要动态创建元素。
当RecyclerView的列表项滚出屏幕的时候，RecyclerView不会销毁该视图，相反而是将这些视图复用到新的列表项中。可以显著提高性能，改善响应能力并且减少功耗

2.RecyclerView怎么使用

• 确定列表或者网格的外观(流式布局、横向布局、纵向布局等)
• 设计列表中每一个项目的样式。通过样式来定义ViewHolder类
• 定义和ViewHolder相关联的Adapter

2.1定义布局

• LinearLayoutManager： 列表布局
• GridLayoutManager ： 网格布局
• StaggeredGridLayoutManager： 流式布局

2.2定义ViewHolder和Adapter

示例代码：CustomAdapter.java

public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {

    private String[] localDataSet;

    /**
     * 自定义布局
     * (custom ViewHolder).
     */
    public static class ViewHolder extends RecyclerView.ViewHolder {
        private final TextView textView;

        public ViewHolder(View view) {
            super(view);
            textView = (TextView) view.findViewById(R.id.textView);
        }

        public TextView getTextView() {
            return textView;
        }
    }

    /**
     * 构造函数，初始化数据集
     *
     * @param dataSet String[] containing the data to populate views to be used
     * by RecyclerView.
     */
    public CustomAdapter(String[] dataSet) {
        localDataSet = dataSet;
    }

    // 创建新的视图
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        // Create a new view, which defines the UI of the list item
        View view = LayoutInflater.from(viewGroup.getContext())
                .inflate(R.layout.text_row_item, viewGroup, false);

        return new ViewHolder(view);
    }

    // 用来绑定数据
    @Override
    public void onBindViewHolder(ViewHolder viewHolder, final int position) {
		viewHolder.getTextView().setText(localDataSet[position]);
    }

    // 返回数据集的大小
    @Override
    public int getItemCount() {
        return localDataSet.length;
    }
}
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列表单个项需要定义xml文件：text_row_item.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="@dimen/list_item_height"
    android:layout_marginLeft="@dimen/margin_medium"
    android:layout_marginRight="@dimen/margin_medium"
    android:gravity="center_vertical">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/element_text"/>
</FrameLayout>
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2.3 Activity或者Fragment中使用

示例代码(fragment中)：RecyclerViewFragment.java

public class RecyclerViewFragment extends Fragment {

    protected RecyclerView mRecyclerView;
    protected CustomAdapter mAdapter;
    protected RecyclerView.LayoutManager mLayoutManager;
    protected String[] mDataset;

 	private enum LayoutManagerType {
        GRID_LAYOUT_MANAGER,
        LINEAR_LAYOUT_MANAGER
    }
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        initDataset();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.recycler_view_frag, container, false);
        rootView.setTag(TAG);
        //定义RecyclerView
        mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);
		//定义布局
        mLayoutManager = new LinearLayoutManager(getActivity());
        mRecyclerView.setLayoutManager(mLayoutManager);
        //初始化adapter
        mAdapter = new CustomAdapter(mDataset);
        //设置适配器
        mRecyclerView.setAdapter(mAdapter);
        
        return rootView;
    }

    
    //初始化数据
    private void initDataset() {
        mDataset = new String[60];
        for (int i = 0; i < 60; i++) {
            mDataset[i] = "This is element #" + i;
        }
    }
}
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recycler_view_frag.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>
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4.最终效果