我有一个视图SubEpoxyRecyclerView
,那是我的父类EpoxyRecyclerView
的一个子类。初始化此视图时,超类EpoxyRecyclerView
调用构造函数主体中setItemSpacingPx(Int)
的方法。
调用此方法时,我的类变量都不会初始化!应用程序在线崩溃itemDecorator.pxBetweenItems
指出itemDecorator
为空,这是不可能的
子类(Kotlin):
class SubEpoxyRecyclerView @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0)
: EpoxyRecyclerView(context, attrs, defStyleAttr) {
private val itemDecorator: Decor = Decor()
private val someInt: Int = 5
private var someBoolean: Boolean = true
override fun setItemSpacingPx(spacingPx: Int) {
// Called from superclass. Debug: itemDecorator is null,
// someInt is 0, someBoolean is false
removeItemDecoration(itemDecorator)
itemDecorator.pxBetweenItems = spacingPx
if (spacingPx > 0) {
addItemDecoration(itemDecorator)
}
}
}
超类(Java - 库):
public class EpoxyRecyclerView extends RecyclerView {
public EpoxyRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
if (attrs != null) {
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.EpoxyRecyclerView,
defStyleAttr, 0);
setItemSpacingPx(a.getDimensionPixelSize(R.styleable.EpoxyRecyclerView_itemSpacing, 0));
a.recycle();
}
init();
}
}
很正常。初始化顺序为
- 父类
- 儿童类
看看这个例子,了解为什么你的代码不起作用:
open class Parent {
init { print("parent ") }
}
class Child : Parent() {
init { print("child ") }
}
fun main(args: Array<String>) {
Child()
}
根据上面的例子,main 方法首先打印"父",然后打印"子"。在您的例子中,SubEpoxyRecyclerView 类的变量不会初始化,因为一旦 EpoxyRecyclerView 的初始化完成,类本身就会被初始化。