MainActivity.kt

/*
 * Copyright 2019 Rúben Sousa
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.rubensousa.recyclerview.nested

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView

class MainActivity : AppCompatActivity() {

    private lateinit var adapter: ParentAdapter
    private lateinit var recyclerView: RecyclerView
    private lateinit var scrollStateHolder: ScrollStateHolder

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        recyclerView = findViewById(R.id.recyclerView)
        scrollStateHolder = ScrollStateHolder(savedInstanceState)
        adapter = ParentAdapter(scrollStateHolder)
        recyclerView.adapter = adapter
        recyclerView.layoutManager = LinearLayoutManager(this)
        loadItems()
    }

    override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)
        scrollStateHolder.onSaveInstanceState(outState)
    }

    private fun loadItems() {
        val lists = arrayListOf<TitledList>()
        repeat(20) { listIndex ->
            val items = arrayListOf<String>()
            repeat(30) { itemIndex -> items.add(itemIndex.toString()) }
            lists.add(TitledList("List number $listIndex", items))
        }
        adapter.setItems(lists)
    }

}