Cornell lec02
Recycle View
background infomation
- Recycle view
- Recycleview.viewholder
- Recycleview.adapter
- layout manager
graph LR
A[Recycle view] --> |view adapter| B[view holder]
How to display a recycle view
- for adapter, we need to override
onCreateViewHolderonBindViewHoldrgetItemCount
package com.example.cornell
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import androidx.recyclerview.widget.RecyclerView.ViewHolder
import com.example.cornell.databinding.ActivityMainBinding
import com.example.cornell.databinding.BookRowItemBinding
class MyBookAdapter(
private val dataSet: List<Book>,
private val printPos: (Int) -> Unit
):
RecyclerView.Adapter<MyBookAdapter.MyViewHolder>(){
inner class MyViewHolder(val binding: BookRowItemBinding) : ViewHolder(binding.root)
private var dataFiltered: List<Book> = dataSet;
var filterTest: CharSequence = ""
set(value) {
field = value
onFilterChange(value)
}
private fun onFilterChange(charString: CharSequence) {
dataFiltered = if (charString.isEmpty()) {
// There's no query, should return back the unfiltered list.
dataSet
} else {
// The filter function returns a list containing only elements
// matching the given predicate. In this case, we can choose
// our predicate to be what we want to filter by. Since we are working
// with books, let's allow filtering by author and title!
dataSet.filter { book ->
book.bookName.contains(charString) || book.author.contains(charString)
}
}
notifyDataSetChanged()
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val binding = BookRowItemBinding.inflate(LayoutInflater.from(parent.context))
return MyViewHolder(binding)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
with(holder) {
this.binding.button.setOnClickListener {
printPos(position)
}
with (dataFiltered[position]) {
binding.bookName.text = this.bookName
binding.author.text = this.author
binding.publisher.text = this.publisher
}
}
}
override fun getItemCount(): Int {
return dataFiltered.size
}
}
package com.example.cornell
import android.content.Intent
import android.os.Bundle
import com.google.android.material.snackbar.Snackbar
import androidx.appcompat.app.AppCompatActivity
import androidx.navigation.findNavController
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.navigateUp
import androidx.navigation.ui.setupActionBarWithNavController
import android.view.Menu
import android.view.MenuItem
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.cornell.databinding.ActivityMainBinding
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
val book_recycle_view = binding.bookList
book_recycle_view.setHasFixedSize(true)
book_recycle_view.layoutManager = GridLayoutManager(this, 2)
val dataSet = mutableListOf<Book>();
for (i in 1..20) {
dataSet.add(Book("Harry Potter$i", "Lorin$i", "Wizard$i"))
}
book_recycle_view.adapter = MyBookAdapter(dataSet) {
val intent = Intent(this, NextActivity::class.java)
intent.putExtra("Pos", it.toString())
startActivity(intent)
}
setContentView(binding.root)
}
}