android.graphics.drawable.ColorDrawable 无法转换为 android.support.v7.widget.RoundRectDrawableWithShadow

Question

我尝试在我的应用程序中使用 CardView，它在我的 xml 布局中运行良好。由于我想在我的代码中而不是通过 xml 生成它们，因此我尝试按照 Android 开发人员 (https://developer.android.com/preview/material/ui-widgets.html#cardview) 的建议使用 CardView.setRadius()-Method 设置半径。

这根本不起作用!我希望有人可以帮助我解决我的问题，或者找到一个很好的 xml 布局解决方法。

这是我的代码:

int height = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 100, getResources().getDisplayMetrics());
        float radius = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 4, getResources().getDisplayMetrics());

        for (String color : colors) {
            CardView card = new CardView(getActivity());
            TextView text = new TextView(getActivity());
            card.setBackgroundColor(Color.parseColor("#"+color));
            card.setLayoutParams(new ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.MATCH_PARENT, height));
            card.setRadius(radius); //Error!!
            text.setText(args.get(colors.indexOf(color)) + " - #" + color);
            card.addView(text);
            group.addView(card);
        }

这是我的日志:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.brobox.materialcolorpalette/com.brobox.materialcolorpalette.MainActivity}: java.lang.ClassCastException: android.graphics.drawable.ColorDrawable cannot be cast to android.support.v7.widget.RoundRectDrawableWithShadow
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2212)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5146)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.ClassCastException: android.graphics.drawable.ColorDrawable cannot be cast to android.support.v7.widget.RoundRectDrawableWithShadow
            at android.support.v7.widget.CardViewEclairMr1.setRadius(CardViewEclairMr1.java:76)
            at android.support.v7.widget.CardView.setRadius(CardView.java:89)
            at com.brobox.materialcolorpalette.ColorFragment.onCreateView(ColorFragment.java:61)
            at android.support.v4.app.Fragment.performCreateView(Fragment.java:1504)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:942)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1121)
            at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
            at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1484)
            at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:571)
            at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
            at android.app.Activity.performStart(Activity.java:5241)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2178)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5146)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)
            at dalvik.system.NativeStart.main(Native Method)

更新:我现在将新的 Lollipop SDK 与 Appcompat 版本 21 一起使用。现在，当我在没有 setRadius() 的情况下尝试它时，它甚至根本不起作用。

新日志:

java.lang.ClassCastException: android.graphics.drawable.ColorDrawable cannot be cast to android.support.v7.widget.RoundRectDrawableWithShadow
            at android.support.v7.widget.CardViewEclairMr1.getShadowBackground(CardViewEclairMr1.java:148)
            at android.support.v7.widget.CardViewEclairMr1.getMinWidth(CardViewEclairMr1.java:139)
            at android.support.v7.widget.CardView.onMeasure(CardView.java:181)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
            at android.view.View.measure(View.java:16521)
            at android.widget.ScrollView.measureChildWithMargins(ScrollView.java:1226)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
            at android.widget.ScrollView.onMeasure(ScrollView.java:326)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
            at android.view.View.measure(View.java:16521)
            at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:848)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:453)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
            at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2552)
            at android.view.View.measure(View.java:16521)
            at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1915)
            at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1291)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5603)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
            at android.view.Choreographer.doCallbacks(Choreographer.java:574)
            at android.view.Choreographer.doFrame(Choreographer.java:544)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5146)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)
            at dalvik.system.NativeStart.main(Native Method)

更新 2:我想这是谷歌的一个错误。所以我为他们指出:https://code.google.com/p/android/issues/detail?id=77843

Answer 1

在调用 View 类中定义的 setBackgroundColor() 方法时出现此错误。

cardView.setBackgroundColor(Color.parseColor("#ffffcc"));

应该调用 setCardBackgroundColor() 方法，该方法特定于 CardViews 并在 CardView 类中定义。

这个设置背景颜色和圆角半径的代码对我有用:

cardView.setCardBackgroundColor(Color.parseColor("#ffffcc"));
cardView.setRadius(50);