android - Runnable 未在 Android 上的 float 操作栏上运行

Question

我一直在尝试让 fab 旋转并更改其图标，但由于某些原因 Runnable 根本不起作用。

代码如下:

private val handler: Handler = Handler()
private var isRotate: Boolean = false
private val rotate: Animation =   RotateAnimation(0.toFloat(),90.toFloat(),0.toFloat(),0.toFloat())

private val r: Runnable = Runnable {
    fun run() {
            if (isRotate) {
                fab2.setImageDrawable(ResourcesCompat.getDrawable(resources, R.drawable.ic_menu_camera, null))
                isRotate = false
            } else {
                fab2.setImageDrawable(ResourcesCompat.getDrawable(resources, R.drawable.ic_menu_gallery, null))
                isRotate = true
            }
        }
    }

override fun onCreate(savedInstanceState: Bundle?) {

    ...

    rotate.duration = 1000
    rotate.repeatCount = 0
    rotate.repeatMode = Animation.REVERSE
    rotate.fillAfter = true

    fab2?.setOnClickListener { view ->
               ObjectAnimator.ofFloat(view,"rotation",0.toFloat(),90.toFloat()).setDuration(800).start()
    view.handler.postDelayed(r,400)
    }
}

Button 旋转但图标没有改变，这意味着 OnClickListener 正在工作，但 Runnable 没有。

我怎样才能做到这一点？

Answer 1

您以错误的方式声明了 Runnable。您声明的 lambda 表达式实际上是 run() 函数，您在其中声明了另一个 run() 函数。

声明对象的正确方法应该是:

private val r: Runnable = object: Runnable {
    override fun run() {
        if (isRotate) {
            fab2.setImageDrawable(ResourcesCompat.getDrawable(resources, R.drawable.ic_menu_camera, null))
            isRotate = false
        } else {
            fab2.setImageDrawable(ResourcesCompat.getDrawable(resources, R.drawable.ic_menu_gallery, null))
            isRotate = true
        }
    }
}

或者(lambda 表达式):

private val r: Runnable = Runnable {
    if (isRotate) {
        fab2.setImageDrawable(ResourcesCompat.getDrawable(resources, R.drawable.ic_menu_camera, null))
        isRotate = false
    } else {
        fab2.setImageDrawable(ResourcesCompat.getDrawable(resources, R.drawable.ic_menu_gallery, null))
        isRotate = true
    }
}