Kotlin学习之路--可添加header／footer的刷新列表

Posted 2022-12-13 xiaohuanqi

博客转移到个人站点：http://www.wangchengmeng.club/2018/02/01/Kotlin/

欢迎来吐槽

BaseRefresh-Kotlin

Kotlin编写刷新列表

首先导入库（使写起来更方便）

compile ‘org.jetbrains.anko:anko-sdk15:0.9.1’

可以直接下面方式写：

//mTvContent直接是xml中的id

mTvContent.text = "Hello-World"

mBtnJump2Main.text = "点击进入"


打开一个Activity 并传递参数：

    startActivity<FoundActivity>("key" to "from mainactivity")

设置点击事件

     mBtnJump2Main.onClick 
        //函数式编程 lamda
        Toast.makeText(this, "点击进入了", Toast.LENGTH_LONG).show()
        startActivity<FoundActivity>("key" to "from mainactivity")
    

封装BaseViewHolder：

open class BaseViewHolder(item: View?) : RecyclerView.ViewHolder(item) 

private lateinit var mContext: Context
private lateinit var mContentView: View
private lateinit var mCacheViews: SparseArray<View>

constructor(context: Context, item: View?) : this(item) 
    mContext = context
    mContentView = item ?: View(context)
    mCacheViews = SparseArray()


/**
 * 根据viewID获取对应的View
 */
fun <T : View> retrieveView(@IdRes viewID: Int): T 
    var view = mCacheViews.get(viewID)

    if (null == view) 
        view = mContentView.find(viewID)
        mCacheViews.put(viewID, view)
    
    return view as T
 

封装BaseAdapter（可添加footer header）

getItemViewType：


    override fun getItemViewType(position: Int): Int 
        var count: Int = mDatas.size
        if (hasHeader()) 
            count++
        
        //表达式
        return if (hasHeader() && 0 == position) 
            BaseAdapter.ITEM_TYPE.HEADER.ordinal
         else if (hasFooter() && position == count) 
            BaseAdapter.ITEM_TYPE.FOOTER.ordinal
         else 
            BaseAdapter.ITEM_TYPE.NORMAL.ordinal
        
    


onCreateViewHolder：


    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): BaseViewHolder =
            when (viewType) 
                BaseAdapter.ITEM_TYPE.HEADER.ordinal -> BaseViewHolder(mContext, mHeaderView)
                BaseAdapter.ITEM_TYPE.FOOTER.ordinal -> BaseViewHolder(mContext, mFooterView)
                else -> BaseViewHolder(mContext, LayoutInflater.from(mContext).inflate(mLayoutID, parent, false))
            


onBindViewHolder：


    override fun onBindViewHolder(holder: BaseViewHolder, position: Int) 
        if (hasHeader() && 0 == position) 
            return
        
        var count = mDatas.size
        if (hasHeader()) 
            count++
        
        if (hasFooter()) 
            count++
        
        if (hasFooter() && position == count - 1) 
            return
        
        if (hasHeader()) 
            onChildBindViewHolder(holder, getData(position - 1))
         else 
            onChildBindViewHolder(holder, getData(position))
        
    

一系列封装后，常用的列表Adapter中所有的代码：

class RvListAdapter(private val mContext: Context, private val mLayout: Int, private val mDatas: List<ListBean>) : BaseAdapter<ListBean>(mContext, mLayout, mDatas) 

constructor(context: Context, listData: ArrayList<ListBean>) : this(context, R.layout.item_list, listData)


override fun onChildBindViewHolder(holder: BaseViewHolder, data: ListBean?) 
    //方式1 - 使用base中的方法获取View
//        holder.retrieveView<TextView>(R.id.mTvName).text = data?.name ?: "chenxiaipie"
//        holder.retrieveView<TextView>(R.id.mTvSex).text = data?.sex ?: "woman"
//        holder.retrieveView<TextView>(R.id.mTvAge).text = data?.age?.toString() ?: ""

    //方式2
    holder.itemView.mTvName.text = data?.name ?: "chenxiaopie"
    holder.itemView.mTvSex.text = data?.sex ?: "woman"
    holder.itemView.mTvAge.text = data?.age?.toString() ?: ""

以上是根据 https://github.com/wangchengmeng/RefreshRecyclerView 所封装下拉刷新列表使用kotlin简单的实现，熟悉一下kotlin的写法，kotlin还有更多实用简单的写法，仅供学习

代码地址：https://github.com/wangchengmeng/BaseRefresh-Kotlin