二进制 XML 文件行 #14:膨胀自定义 ViewGroup 类时出错

Question

膨胀自定义视图组时出现问题。

无法启动活动 二进制 XML 文件行 #14：二进制 XML 文件行 #14：膨胀类 com.example.interactiveplatform.view.GraphLayout 时出错。

我搜索了这个问题，构造函数有问题。

<LinearLayout
android:id="@+id/graph"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
tools:context=".MainActivity">
<com.example.interactiveplatform.view.GraphLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
</com.example.interactiveplatform.view.GraphLayout>
</LinearLayout>

class GraphLayout(context: Context, attrs: AttributeSet, var chapterAdapter: ChapterAdapter) : ViewGroup(context, attrs) {
private val detector: GestureDetector
private val mMoveAndScaleHandler: MoveAndScaleHandler
private val myListener: GestureDetector.SimpleOnGestureListener
private var spacing = 0
init {
myListener = object : GestureDetector.SimpleOnGestureListener() {
override fun onDown(e: MotionEvent?): Boolean {
return true
}
}
detector = GestureDetector(context, myListener)
mMoveAndScaleHandler = MoveAndScaleHandler(context, this, chapterAdapter)
}

override fun onLayout(p0: Boolean, p1: Int, p2: Int, p3: Int, p4: Int) {
for(i in 0 until childCount){
val v = getChildAt(i)
v.layout(v.left, v.top, v.right, v.bottom)
}
}

override fun onTouchEvent(event: MotionEvent): Boolean {
detector.onTouchEvent(event)
invalidate()
return mMoveAndScaleHandler.onTouchEvent(event)
}

override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
setMeasuredDimension(400 * chapterAdapter.numberChapters,chapterAdapter.heightScreen)
}

}

Answer 1

当您通过 XML 实例化自定义视图时，您无法传递自定义构造函数参数，如chapterAdapter.此外，您必须支持所有Android的视图构造函数。例如，您可以像这样操作：

class GraphLayout @JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : ViewGroup(context, attrs, defStyleAttr)