什麼是ListView
ListView是用於顯示列表的UI控件.不過當前主流的已經是RecyclerView了,更強大,更好用.
基礎樣例
效果圖
方案簡要介紹
- 在activity對應的佈局文件中增加
ListView
<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
- 新增一個Adapter用於展示列表中每一行內容(含對應佈局文件)
詳見下面完整代碼中的ListViewAdapter及其佈局文件. - 在activity中實例化Adapter,設置數據,並將adapter設置給ListView
private fun initListView() {
var dataList = getData()
val adapter = ListViewAdapter(this)
adapter.setData(dataList)
listView.adapter = adapter
//隱藏自帶的分隔符,在ListViewAdapter對應的佈局裏自定義分隔符,這樣可以更靈活。
listView.divider = null
//添加點擊事件
listView.setOnItemClickListener { adapterView, _, position, _ ->
val text = adapterView.getItemAtPosition(position).toString()
toast(text)
}
}
private fun getData(): List<String> {
val dataList = ArrayList<String>()
for (index in 0 until 100) {
val text = " 數據$index "
dataList.add(text)
}
return dataList
}
完整代碼
- activity代碼:MainActivity
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
initListView()
}
private fun initListView() {
var dataList = getData()
val adapter = ListViewAdapter(this)
adapter.setData(dataList)
listView.adapter = adapter
//隱藏自帶的分隔符,在ListViewAdapter對應的佈局裏自定義分隔符,這樣可以更靈活。
listView.divider = null
//添加點擊事件
listView.setOnItemClickListener { adapterView, _, position, _ ->
val text = adapterView.getItemAtPosition(position).toString()
toast(text)
}
}
private fun getData(): List<String> {
val dataList = ArrayList<String>()
for (index in 0 until 100) {
val text = " 數據$index "
dataList.add(text)
}
return dataList
}
/**
* 顯示toast短暫提示
*/
private fun toast(text: String) = Toast.makeText(this, text, Toast.LENGTH_SHORT).show()
}
- MainActivity對應佈局文件: activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
- ListView對應Adapter: ListViewAdapter
class ListViewAdapter(var context: Context) : BaseAdapter() {
private var mDataList = mutableListOf<String>()
/**
* 設置數據
*/
fun setData(dataList: List<String>) {
mDataList.clear()
mDataList.addAll(dataList)
//數據變更後,需要調用notifyDataSetChanged通知數據變化。
notifyDataSetChanged()
}
override fun getView(position: Int, convertView: View?, viewGroup: ViewGroup?): View {
var viewHolder: ViewHolder
var view: View
//下面對convertView進行判斷,是爲了複用已存在的視圖,提升效率。
if (convertView == null) {
view = View.inflate(context, R.layout.item_layout, null);
viewHolder = ViewHolder(view)
view.tag = viewHolder
} else {
view = convertView
viewHolder = view.tag as ViewHolder
}
//獲取當前位置數據
val item = getItem(position)
//顯示用戶名
if (item is String) {
viewHolder.nameTv.text = item
}
return view
}
override fun getItem(position: Int): Any {
return mDataList[position]
}
override fun getItemId(position: Int): Long {
return 0
}
override fun getCount(): Int {
return mDataList.size
}
class ViewHolder(view: View) {
var nameTv: TextView = view.findViewById(R.id.nameTv)
}
}
- ListViewAdapter對應佈局文件: item_layout.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/nameTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
tools:text="姓名" />
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_marginStart="15dp"
android:layout_marginEnd="15dp"
android:layout_marginTop="5dp"
android:background="#E7E7E7" />
</LinearLayout>