我是java,eclipse和android开发的新手,所以我可能会遗漏一些简单的东西,虽然我已经检查了几次拼写等基本内容.
由于公共Android SDK中没有数字选择器控件(例如日期选择器中使用的控件),因此conventional wisdom将“克隆并拥有”Android源中存在的控件.
为了做到这一点,我将NumberPicker的代码复制到我的项目及其依赖项NumberPickerButton中.我也复制了支持资源.
我遇到的问题是,当我尝试在布局中包含NumberPicker时,Eclipse中布局的呈现版本不起作用.
<com.spencerandbrown.PatientTracker1.NumberPicker
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/spanEnd2" />
添加该标记会导致XML文件的Layout视图仅显示以下错误.
ClassCastException: com.spencerandbrown.PatientTracker1.NumberPickerButton cannot be cast to com.spencerandbrown.PatientTracker1.NumberPickerButton
奇怪的是控件在运行时工作,它不会在Eclipse中呈现.
这个问题有解决方案吗？我只是做错了吗？
如有必要,我可以从我的项目中包含更多代码来澄清.
如果我引用内部Android小部件,它在Eclipse布局视图中工作正常,但是以这种方式进行交互是笨拙的,并且将来可能会中断.
<com.android.internal.widget.NumberPicker
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/spanStart"/>
这是Eclipse的堆栈跟踪.
java.lang.classCastException: com.spencerandbrown.PatientTracker1.NumberPickerButton cannot be cast to com.spencerandbrown.PatientTracker1.NumberPickerButton
at com.spencerandbrown.PatientTracker1.NumberPicker.<init>(NumberPicker.java:110)
at com.spencerandbrown.PatientTracker1.NumberPicker.<init>(NumberPicker.java:98)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(UnkNown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(UnkNown Source)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:198)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:126)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:617)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:620)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:620)
at android.view.LayoutInflater.inflate(LayoutInflater.java:407)
at android.view.LayoutInflater.inflate(LayoutInflater.java:296)
at com.android.layoutlib.bridge.Bridge.computeLayout(Bridge.java:377)
at com.android.ide.eclipse.adt.internal.editors.layout.GraphicalLayoutEditor.computeLayout(UnkNown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.GraphicalLayoutEditor.recomputeLayout(UnkNown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.GraphicalLayoutEditor.activated(UnkNown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditor.pageChange(UnkNown Source)
at org.eclipse.ui.part.MultiPageEditorPart$2.widgetSelected(MultiPageEditorPart.java:291)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:228)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1176)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1200)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1185)
at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1025)
at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:3256)
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:2045)
at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:323)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1176)
at org.eclipse.swt.widgets.display.runDeferredEvents(display.java:3493)
at org.eclipse.swt.widgets.display.readAnddispatch(display.java:3112)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:368)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514)
at org.eclipse.equinox.launcher.Main.run(Main.java:1311)
解决方法:
解决方法：我发现如果我捕获并忽略ClassCastException,显然然后不尝试对我试图找到的View做任何事情,就没有其他问题了,我可以再次使用布局编辑器：编辑器将非常高兴地加载,初始化和绘制有问题的视图,你只是无法投射到它的类.
try {
picker = (NumberPicker) findViewById(R.id.myPicker);
picker.blargh();
// everything else involving picker
} catch (ClassCastException issue6894) {} // ignore
