ConcatMapOperatorActivity.kt

package com.coderefer.rxandroidexamples.intro.operators.transform

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import com.coderefer.rxandroidexamples.R
import io.reactivex.Observable
import io.reactivex.android.schedulers.AndroidSchedulers
import io.reactivex.schedulers.Schedulers
import java.util.concurrent.TimeUnit

private const val TAG = "ConcatMapOperator"
class ConcatMapOperatorActivity : AppCompatActivity() {

    private val items: List<Int> = listOf(1,2,3,4,5)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_concat_map_operator)
        Observable.fromIterable(items)
                .concatMap {
                    Observable.just(it * 2)
                            .delay(it/10L, TimeUnit.SECONDS)
                }
                .doOnNext{
                    Log.d(TAG, it.toString())
                }
                .observeOn(Schedulers.io())
                .subscribeOn(AndroidSchedulers.mainThread())
                .subscribe()
    }
}