【发布时间】:2015-11-21 21:03:15
【问题描述】:
我正在为小孩子编写一个用于学习数学的 Android 应用程序,并且我正在致力于让用户在正确回答所有问题时获得奖品。我动态地在屏幕右侧添加了一些视图,以告诉用户他/她中奖了。 (每一个可能的问题选项都有对应的奖品!)左边是用来显示分数的。但是,该应用程序崩溃了。我试图查看调用堆栈,看看我在哪里做错了。但是我的方法都没有在调用堆栈上!
java.lang.ClassCastException: android.widget.LinearLayout$LayoutParams cannot be cast to android.widget.FrameLayout$LayoutParams
at android.widget.FrameLayout.onMeasure(FrameLayout.java:315)
at android.widget.ScrollView.onMeasure(ScrollView.java:321)
at android.view.View.measure(View.java:16030)
at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:1034)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:590)
at android.view.View.measure(View.java:16030)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:314)
at android.view.View.measure(View.java:16030)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:302)
at android.view.View.measure(View.java:16030)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:314)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2196)
at android.view.View.measure(View.java:16030)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1915)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1290)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1009)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5508)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
at android.view.Choreographer.doCallbacks(Choreographer.java:562)
at android.view.Choreographer.doFrame(Choreographer.java:532)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:213)
at android.app.ActivityThread.main(ActivityThread.java:5225)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:741)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
at dalvik.system.NativeStart.main(Native Method)
看到了吗?我的包名叫做com.smartkidslovemaths,但它不是调用堆栈之一!我怎么知道我哪里做错了?
无论如何,我认为我的一些代码是相关的。这是屏幕右侧的布局:
<ScrollView
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/right_side"
android:orientation="vertical">
</LinearLayout>
</ScrollView>
这是我添加视图的方法,注意这个方法是在onCreate 方法中调用的。
private void displayPrize () {
((LinearLayout)findViewById (R.id.right_side)).setLayoutParams (new LinearLayout.LayoutParams (FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT));
TextView text = new TextView (this);
final LinearLayout.LayoutParams textParams =
new LinearLayout.LayoutParams (
ViewGroup.LayoutParams.WRAP_CONTENT, 0, 1F
);
final LinearLayout.LayoutParams imageParams =
new LinearLayout.LayoutParams (
ViewGroup.LayoutParams.MATCH_PARENT, 0, 8F
);
text.setLayoutParams (textParams);
Resources res = getResources ();
QuestionOptions options = QuestionsActivity.Options.getOptions ();
switch (options.getDigitCount ()) {
case 1:
default:
text.setText (res.getText (R.string.earn_star_text));
break;
case 2:
text.setText (res.getText (R.string.earn_badge_text));
break;
case 3:
text.setText (res.getText (R.string.earn_trophy_text));
break;
}
text.setTextSize (res.getDimension (R.dimen.answer_text_size) / 4);
((LinearLayout)findViewById (R.id.right_side)).addView (text);
ImageView image = new ImageView (this);
image.setLayoutParams (imageParams);
int resID = QuestionOptionMaps.getOptionsDrawableMap ().get (options);
image.setImageResource (resID);
((LinearLayout)findViewById (R.id.right_side)).addView (image);
}
我真的不知道我哪里做错了。或者也许我是正确的,这只是一个 Android 错误?
【问题讨论】:
-
这是一个 ClassCastException。在某个地方,它试图将类型 A 转换为(不相关的)类型 B。
-
但它发生在 android 的内部工作中。我该怎么解决这个问题? @Stultuske
-
您将这些
findViewById调用转换为LinearLayout的理由是什么? Android 告诉你这是不可能的,因为类在运行时不相关。 -
@Makoto 如果那是我做错的,调用堆栈会说,对吧?而且,我发现的观点 是
LinearLayout! -
不是每个异常都有一个调用堆栈到你的代码中——你不应该期望它。一个简单的示例是由系统膨胀的无效 xml 布局 - 因为您自己不膨胀它们,所以异常调用堆栈不会显示您的任何代码。这是完全正常的,不是 Android 中的错误。
标签: java android android-xml callstack