Group分组列表的实现 RecyclerView（二）

最新推荐文章于 2024-09-07 02:55:39 发布

nothingwxq

最新推荐文章于 2024-09-07 02:55:39 发布

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分类专栏： Android进阶文章标签： android 5.0新特性 RecyclerView使用初级分组列表

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本文介绍如何在Android项目中使用RecyclerView实现分组列表。首先，不详细说明activity_main.xml，主要关注MainActivity.java。分组布局包含两种类型：只有标题的分组头item_text.xml。接着，通过viewType创建对应的ViewHolder，并在onCreateViewHolder中根据布局类型实例化ViewHolder。在onBindViewHolder中，根据holder.getItemViewType()绑定对应的数据。最后，重写getItemViewType方法，根据位置判断item类型。

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分组列表在iOS、以及android实际项目中均比较常见本文是使用强大的RecyclerView来实现分组列表。先看代码：

1 首先activity_main.xml和android 5.0新特性 RecyclerView 使用初级主布局一样不再赘述。

2.MainActivity.java

public class MainActivity extends ActionBarActivity {

    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;
    private List<String> mData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
        // setlayoutManager
        mLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(mLayoutManager);
        //setAdapter
        mData = new ArrayList<>();
        for (int i = 0; i < 100; i++) {
            mData.add("this is content:" + i);
        }
        mData.add(3,"this is title: 1");
        mData.add(15,"this is title: 2");
        mData.add(20,"this is title: 3");
        mData.add(60,"this is title: 4");
        mData.add(77,"this is title: 5");
        mAdapter = new RecyclerViewAdapter(this,mData);
        mRecyclerView.setAdapter(mAdapter);
    }

}

上述中。只在数据mData中添加了 this is title作为标识。实际项目中需要添加相应的处理。

来看看我们的分组布局。

分为两个：

只有标题的分组头item_text.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:clickable="true"
    android:focusable="true"
    android:background="?selectableItemBackground">
    <TextView
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:id="@+id/text"
        android:textSize="18sp"
        android:layout_marginLeft="@dimen/activity_horizontal_margin"
        android:textColor="#0000ff"
        android:textAppearance="?android:attr/textAppearanceMedium"/>
</RelativeLayout>

以及具体的内容 item_image.xml（仍以上次的xml为例）：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/item"
    android:layout_width="match_parent"
    android:layout_height="?listPreferredItemHeight"
    android:clickable="true"
    android:focusable="true"
    android:foreground="?selectableItemBackground">

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="@dimen/activity_horizontal_margin"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <ImageView
        android:id="@+id/image"
        android:layout_width="?listPreferredItemHeight"
        android:layout_height="match_parent"
        android:layout_gravity="center_vertical|right"
        android:scaleType="center"
      />
</FrameLayout>

接下来是我们的adapter中真正的实现RecyclerViewAdapter.java：

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

    private static final int TYPE_IMAGE = 0;
    private static final int TYPE_GROUP = 1;
    private List<String> mData = new ArrayList<>();
    private Context mContext;

    private boolean isTitle(int pos){
        if(mData.get(pos).startsWith("this is title:")) {
            return true;
        }
        return false;
    }

    public RecyclerViewAdapter(Context mContext, List<String> mData) {
        this.mContext = mContext;
        this.mData = mData;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater mInflater = LayoutInflater.from (mContext);
        switch ( viewType ) {
            case TYPE_IMAGE:
                ViewGroup vImage = ( ViewGroup ) mInflater.inflate ( R.layout.item_image, parent, false );
                ImageViewHolder vhImage = new ImageViewHolder ( vImage );
                return vhImage;
            case TYPE_GROUP:
                ViewGroup vGroup = ( ViewGroup ) mInflater.inflate ( R.layout.item_text, parent, false );
                GroupViewHolder vhGroup = new GroupViewHolder ( vGroup );
                return vhGroup;
        }
        return null;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        switch ( holder.getItemViewType () ) {
            case TYPE_IMAGE:
                ImageViewHolder imageViewHolder = ( ImageViewHolder ) holder;
                imageViewHolder.mImage.setImageResource ( R.drawable.ic_reorder_grey_500_24dp);
                imageViewHolder.mTitle.setText(mData.get(position));
                break;
            case TYPE_GROUP:
                GroupViewHolder groupViewHolder = ( GroupViewHolder ) holder;
                groupViewHolder.mTitle.setText ( mData.get(position));
                break;
        }
    }

    @Override
    public int getItemCount() {
        return mData.size ();
    }

    @Override
    public int getItemViewType ( int position ) {
        int viewType;
        if (!isTitle(position) ) {
            viewType = TYPE_IMAGE;
        } else {
            viewType = TYPE_GROUP;
        }
        return viewType;
    }

    public class GroupViewHolder extends RecyclerView.ViewHolder {
        TextView mTitle;
        public GroupViewHolder ( View itemView ) {
            super(itemView);
            mTitle= (TextView) itemView.findViewById(R.id.text);
        }

    }
    public class ImageViewHolder extends RecyclerView.ViewHolder {
        TextView mTitle;
        ImageView mImage;
        public ImageViewHolder ( View itemView ) {
            super(itemView );
            mTitle= (TextView) itemView.findViewById(R.id.text);
            mImage= (ImageView) itemView.findViewById(R.id.image);
        }
    }

}

该段代码。实际上上述代码跟listView的分组几乎一模一样。下面做一个简述：
//区分分组
1. private boolean isTitle(int pos)

2. 通过viewType创建对应的ViewHolder

public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater mInflater = LayoutInflater.from (mContext);
switch ( viewType ) {
case TYPE_IMAGE:
ViewGroup vImage = ( ViewGroup ) mInflater.inflate ( R.layout.item_image, parent, false );
ImageViewHolder vhImage = new ImageViewHolder ( vImage );
return vhImage;
case TYPE_GROUP:
ViewGroup vGroup = ( ViewGroup ) mInflater.inflate ( R.layout.item_text, parent, false );
GroupViewHolder vhGroup = new GroupViewHolder ( vGroup );
return vhGroup;
}
return null;
}

3. 根据holder.getItemViewType ()获取对应的ViewHolder绑定对应的数据

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
switch ( holder.getItemViewType () ) {
case TYPE_IMAGE:
ImageViewHolder imageViewHolder = ( ImageViewHolder ) holder;
imageViewHolder.mImage.setImageResource ( R.drawable.ic_reorder_grey_500_24dp);
imageViewHolder.mTitle.setText(mData.get(position));
break;
case TYPE_GROUP:
GroupViewHolder groupViewHolder = ( GroupViewHolder ) holder;
groupViewHolder.mTitle.setText ( mData.get(position));
break;
}
}

4.重写 getItemViewType

@Override
public int getItemViewType ( int position ) {
int viewType;
if (!isTitle(position) ) {
viewType = TYPE_IMAGE;
} else {
viewType = TYPE_GROUP;
}
return viewType;
}