我将 ViewPageIndicator 添加到我现有的项目中。我在下面的链接中做所有事情。
https://www.youtube.com/watch?v=yTaIQ0LMLy0
当我将 CirclePageIndicator 添加到布局中时，出现此错误。
异常堆栈跟踪：
java.lang.NullPointerException
at com.android.layoutlib.bridge.android.BridgeContext.obtainStyledAttributes(BridgeContext.java:568)
at android.view.View.<init>(View.java:3283)
at com.viewpagerindicator.CirclePageIndicator.<init>(CirclePageIndicator.java:76)
at com.viewpagerindicator.CirclePageIndicator.<init>(CirclePageIndicator.java:72)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(ProjectCallback.java:422)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(ProjectCallback.java:179)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:207)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:135)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:746)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:718)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:749)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:718)
at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
at android.view.LayoutInflater.inflate(LayoutInflater.java:372)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:385)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:332)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:325)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.RenderService.createRenderSession(RenderService.java:440)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(GraphicalEditorPart.java:1545)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(GraphicalEditorPart.java:1302)
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.recomputeLayout(LayoutEditorDelegate.java:410)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.SelectionManager.setSelection(SelectionManager.java:285)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.LayoutCanvasViewer.setSelection(LayoutCanvasViewer.java:120)
at org.eclipse.jface.viewers.Viewer.setSelection(Viewer.java:394)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.selectionChanged(GraphicalEditorPart.java:611)
at org.eclipse.ui.internal.e4.compatibility.SelectionService.notifyListeners(SelectionService.java:154)
at org.eclipse.ui.internal.e4.compatibility.SelectionService.updateSelection(SelectionService.java:119)
at org.eclipse.ui.internal.WorkbenchPage$E4PartListener.partActivated(WorkbenchPage.java:170)
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl$2.run(PartServiceImpl.java:193)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.firePartActivated(PartServiceImpl.java:191)
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:596)
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:549)
at org.eclipse.e4.ui.internal.workbench.swt.AbstractPartRenderer.activate(AbstractPartRenderer.java:105)
at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer$1.handleEvent(ContributedPartRenderer.java:61)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1058)
at org.eclipse.swt.widgets.Shell.setActiveControl(Shell.java:1447)
at org.eclipse.swt.widgets.Shell.WM_MOUSEACTIVATE(Shell.java:2328)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4572)
at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:341)
at org.eclipse.swt.widgets.Decorations.windowProc(Decorations.java:1627)
at org.eclipse.swt.widgets.Shell.windowProc(Shell.java:2069)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Scrollable.callWindowProc(Scrollable.java:80)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2541)
at org.eclipse.swt.widgets.Tree.callWindowProc(Tree.java:1442)
at org.eclipse.swt.widgets.Tree.windowProc(Tree.java:5878)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.CallWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.CallWindowProc(OS.java:2440)
at org.eclipse.swt.widgets.Tree.callWindowProc(Tree.java:1534)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Tree.windowProc(Tree.java:5977)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4989)
at org.eclipse.swt.internal.win32.OS.PeekMessageW(Native Method)
at org.eclipse.swt.internal.win32.OS.PeekMessage(OS.java:3129)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3753)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1053)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:942)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:86)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:588)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
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:353)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
at org.eclipse.equinox.launcher.Main.main(Main.java:1414)
这是我的布局 xml。
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:layout_below="@id/linearLayout1"
android:orientation="vertical" >
<android.support.v4.view.ViewPager
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<com.viewpagerindicator.CirclePageIndicator
android:id="@+id/indicator"
android:padding="10dip"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
/>
</LinearLayout>
在代码端（onCreate 方法）之后，我添加了代码。
CirclePageIndicator titleIndicator = (CirclePageIndicator)findViewById(R.id.indicator);
titleIndicator.setViewPager(viewPager);
当我启动应用程序时，没有显示指示器。可能是什么问题？