如何用Kotlin从RecyclerView (ArrayList)中保存数据？
如何用Kotlin从RecyclerView (ArrayList)中保存数据？
提问于 2021-12-31 02:37:22
我在Kotlin中创建了一个RecyclerView，并且希望保存RecyclerView ( ArrayList)中的数据，例如使用GSON。我已经搜了很多遍了，但找不到有效的解决办法。下面是我的当前代码：(没有保存函数)
MainActivity.kt：
class MainActivity : AppCompatActivity(), ExampleAdapter.OnItemClickListener {
private val exampleList = generateDummyList(500)
private val adapter = ExampleAdapter(exampleList, this)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
recycler_view.adapter = adapter
recycler_view.layoutManager = LinearLayoutManager(this)
recycler_view.setHasFixedSize(true)
}
fun insertItem(view: View) {
val index = Random.nextInt(8)
val newItem = ExampleItem(
R.drawable.ic_android,
"New item at position $index",
"Line 2"
)
exampleList.add(index, newItem)
adapter.notifyItemInserted(index)
}
fun removeItem(view: View) {
val index = Random.nextInt(8)
exampleList.removeAt(index)
adapter.notifyItemRemoved(index)
}
override fun onItemClick(position: Int) {
Toast.makeText(this, "Item $position clicked", Toast.LENGTH_SHORT).show()
val clickedItem = exampleList[position]
clickedItem.text1 = "Clicked"
adapter.notifyItemChanged(position)
}
private fun generateDummyList(size: Int): ArrayList<ExampleItem> {
val list = ArrayList<ExampleItem>()
for (i in 0 until size) {
val drawable = when (i % 3) {
0 -> R.drawable.ic_android
1 -> R.drawable.ic_audio
else -> R.drawable.ic_sun
}
val item = ExampleItem(drawable, "Item $i", "Line 2")
list += item
}
return list
}
}ExampleItem.kt：
data class ExampleItem(val imageResource: Int, var text1: String, var text2: String)ExampleAdapter.kt：
class ExampleAdapter(
private val exampleList: List<ExampleItem>,
private val listener: OnItemClickListener) :
RecyclerView.Adapter<ExampleAdapter.ExampleViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ExampleViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.example_item,
parent, false)
return ExampleViewHolder(itemView)
}
override fun onBindViewHolder(holder: ExampleViewHolder, position: Int) {
val currentItem = exampleList[position]
holder.imageView.setImageResource(currentItem.imageResource)
holder.textView1.text = currentItem.text1
holder.textView2.text = currentItem.text2
}
override fun getItemCount() = exampleList.size
inner class ExampleViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView),
View.OnClickListener {
val imageView: ImageView = itemView.image_view
val textView1: TextView = itemView.text_view_1
val textView2: TextView = itemView.text_view_2
init {
itemView.setOnClickListener(this)
}
override fun onClick(v: View?) {
val position = adapterPosition
if (position != RecyclerView.NO_POSITION) {
listener.onItemClick(position)
}
}
}
interface OnItemClickListener {
fun onItemClick(position: Int)
}
}回答 1
Stack Overflow用户
发布于 2021-12-31 02:55:23
首先，需要将数据转换为json，方法是在onBindViewHolder中使用json对象
String json = {"phonetype":"N95","cat":"WP"};
try {
JSONObject obj = new JSONObject(json);
Log.d("My App", obj.toString());
} catch (Throwable t) {
Log.e("My App", "Could not parse malformed JSON: \"" + json + "\"");
}如果您想要保存，则可以使用共享首选项。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/70538521
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