【Android,kotlin】写倒计时CountDown的正确姿势

• 方法一(初级) 利用Handler来实现

申明

private var countDownHandler = Handler()
var countDownTime = Constants.RETURN_TIME//自己设定的时间
private val countDown = object : Runnable {
	override fun run() {
    if (countDownTime >= 0) {
		countDownHandler.postDelayed(this, 1000)//每秒
        //执行逻辑
        //可以动态的更新UI:还有5s返回之类的
	} else {
    	//停止的逻辑
    }
    countDownTime--
    }
}

调用

viewBinding.defaultPaneDefault.defaultPaneDefaultQr.setOnClickListener {
	 //点击事件逻辑
	countDownTime = Constants.RETURN_TIME
	countDownHandler.postDelayed(
		countDown, 0)
}

• 方法二(进阶) 利用CountDown并封装成Util实现

兼顾生命周期, 防止内存泄漏

UtilKCountDown

package com.mozhimen.basick.utilk

import android.os.CountDownTimer
import androidx.lifecycle.DefaultLifecycleObserver
import androidx.lifecycle.LifecycleOwner

/**
 * @ClassName UtilKCountDown
 * @Description TODO
 * @Author Kolin Zhao / Mozhimen
 * @Date 2022/9/26 15:57
 * @Version 1.0
 */
class UtilKCountDown(private val _lifecycleOwner: LifecycleOwner) : DefaultLifecycleObserver {

    private var _utilKCountDownListener: IUtilKCountDownListener? = null
    private var _countDownTimer: CountDownTimer? = null

    init {
        _lifecycleOwner.lifecycle.addObserver(this)
    }

    interface IUtilKCountDownListener {
        fun onTick(millisUntilFinished: Long)
        fun onFinish()
    }

    fun start(countDownMilliseconds: Long, listener: IUtilKCountDownListener? = null) {
        listener?.let { _utilKCountDownListener = it }
        _countDownTimer = UtilKCountDownTimer(countDownMilliseconds)
        _countDownTimer!!.start()
    }

    fun stop() {
        _countDownTimer?.cancel()
        _countDownTimer = null
    }

    override fun onDestroy(owner: LifecycleOwner) {
        stop()
        _lifecycleOwner.lifecycle.removeObserver(this)
    }

    private inner class UtilKCountDownTimer(countDownMilliseconds: Long) : CountDownTimer(countDownMilliseconds, 1000) {
        override fun onTick(millisUntilFinished: Long) {
            _utilKCountDownListener?.onTick(millisUntilFinished)
        }

        override fun onFinish() {
            _utilKCountDownListener?.onFinish()
        }
    }
}

调用

    private val _countDown: UtilKCountDown = UtilKCountDown(this)

    private companion object {
        val TIME_DELAY = 5 * 1000L
    }

    override fun initData(savedInstanceState: Bundle?) {
        _countDown.start(TIME_DELAY, object : UtilKCountDown.IUtilKCountDownListener {
            override fun onTick(millisUntilFinished: Long) {

            }

            override fun onFinish() {
                
            }
        })
    }

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