xiaofeidev

import org.json.JSONException
import org.json.JSONObject
import java.io.BufferedInputStream
import java.io.ByteArrayOutputStream
import java.io.IOException
import java.lang.Exception
import java.net.*

/**
 * Created by xiaofei on 2019/1/15.

xiaofeidev

/**
 * Created by xiaofei on 2018/11/30.
 * desc:Boolean Extension, Say Goodbye to if-else expression
 */
 
sealed class BooleanExt<out T>//定义成协变

object Otherwise : BooleanExt<Nothing>()//Nothing是所有类型的子类型，协变的类继承关系和泛型参数类型继承关系一致

class TransferData<T>(val data: T) : BooleanExt<T>()//data只涉及到了只读的操作

xiaofeidev

val timer:TextView = findViewById(R.id.textView) //这里的 timer 就是你要控制显示倒计时效果的 TextView 
val mSubscription: Subscription? = null // Subscription 对象，用于取消订阅关系，防止内存泄露
//开始倒计时，用 RxJava2 实现
    private fun timer() {
        val count = 59L
        Flowable.interval(0, 1, TimeUnit.SECONDS)//设置0延迟，每隔一秒发送一条数据
                .onBackpressureBuffer()//加上背压策略
                .take(count) //设置循环次数
                .map{ aLong ->
                    count - aLong //