Android XMLのグラフィカルレイアウトビューア - カスタムビューをインスタンス化できません。クラスが見つかりませんか？

Question

OvalShape、a.k.a. android.graphics.drawable.shapes.OvalShapeを描画しようとする非常に単純なカスタムビューがあります。したがって、SDKのネイティブです。

これは、エラーのタイトルです：

com.dan.test.ui.ArcButton failed to instantiate. 

これはエラー体である：

java.lang.ClassNotFoundException: android.graphics.drawable.shapes.OvalShape 
at com.android.ide.eclipse.adt.internal.resources.manager.ProjectClassLoader.findClass(ProjectClassLoader.java:105) 
at java.lang.ClassLoader.loadClass(Unknown Source) 
at java.lang.ClassLoader.loadClass(Unknown Source) 
at java.lang.Class.getDeclaredConstructors0(Native Method) 
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source) 
at java.lang.Class.getConstructor0(Unknown Source) 
at java.lang.Class.getConstructor(Unknown Source) 
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(ProjectCallback.java:327) 
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(ProjectCallback.java:166) 
at com.android.layoutlib.bridge.android.BridgeInflater.loadCustomView(BridgeInflater.java:205) 
at com.android.layoutlib.bridge.android.BridgeInflater.createViewFromTag(BridgeInflater.java:133) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:623) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:626) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:408) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:296) 
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:279) 
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:318) 
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:372) 
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(GraphicalEditorPart.java:1361) 
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(GraphicalEditorPart.java:1115) 
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.activated(GraphicalEditorPart.java:941) 
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.partActivated(LayoutEditorDelegate.java:477) 
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.partBroughtToTop(LayoutEditorDelegate.java:487) 
at org.eclipse.ui.internal.PartListenerList$2.run(PartListenerList.java:87) 
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) 
at org.eclipse.core.runtime.Platform.run(Platform.java:888) 
at org.eclipse.ui.internal.PartListenerList.fireEvent(PartListenerList.java:57) 
at org.eclipse.ui.internal.PartListenerList.firePartBroughtToTop(PartListenerList.java:85) 
at org.eclipse.ui.internal.PartService.firePartBroughtToTop(PartService.java:208) 
at org.eclipse.ui.internal.WorkbenchPagePartList.firePartBroughtToTop(WorkbenchPagePartList.java:76) 
at org.eclipse.ui.internal.WorkbenchPagePartList.fireActiveEditorChanged(WorkbenchPagePartList.java:52) 
at org.eclipse.ui.internal.PartList.setActiveEditor(PartList.java:162) 
at org.eclipse.ui.internal.WorkbenchPage.makeActiveEditor(WorkbenchPage.java:1355) 
at org.eclipse.ui.internal.WorkbenchPage.setActivePart(WorkbenchPage.java:3629) 
at org.eclipse.ui.internal.WorkbenchPage.requestActivation(WorkbenchPage.java:3159) 
at org.eclipse.ui.internal.PartPane.requestActivation(PartPane.java:279) 
at org.eclipse.ui.internal.EditorPane.requestActivation(EditorPane.java:98) 
at org.eclipse.ui.internal.PartPane.setFocus(PartPane.java:325) 
at org.eclipse.ui.internal.EditorPane.setFocus(EditorPane.java:127) 
at org.eclipse.ui.internal.PartStack.presentationSelectionChanged(PartStack.java:837) 
at org.eclipse.ui.internal.PartStack.access$1(PartStack.java:823) 
at org.eclipse.ui.internal.PartStack$1.selectPart(PartStack.java:137) 
at org.eclipse.ui.internal.presentations.util.TabbedStackPresentation$1.handleEvent(TabbedStackPresentation.java:133) 
at org.eclipse.ui.internal.presentations.util.AbstractTabFolder.fireEvent(AbstractTabFolder.java:269) 
at org.eclipse.ui.internal.presentations.util.AbstractTabFolder.fireEvent(AbstractTabFolder.java:278) 
at org.eclipse.ui.internal.presentations.defaultpresentation.DefaultTabFolder.access$1(DefaultTabFolder.java:1) 
at org.eclipse.ui.internal.presentations.defaultpresentation.DefaultTabFolder$2.handleEvent(DefaultTabFolder.java:88) 
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:1062) 
at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:774) 
at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:2746) 
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:1433) 
at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:257) 
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.Display.runDeferredEvents(Display.java:4165) 
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754) 
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2701) 
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2665) 
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2499) 
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:679) 
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) 
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:668) 
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) 
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123) 
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:344) 
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) 
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:622) 
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577) 
at org.eclipse.equinox.launcher.Main.run(Main.java:1410) 
at org.eclipse.equinox.launcher.Main.main(Main.java:1386) 

これは私のレイアウトXMLの一部です：

<com.dan.test.ui.ArcButton 
android:id="@+id/btn_arc" 
android:layout_width="100dip" 
android:layout_height="75dip" 
android:layout_gravity="center" 
/> 

これは私のonDrawでありますArcButtonクラスのコード：

@Override 
protected void onDraw(Canvas canvas) 
{ 
    super.onDraw(canvas); 

    // SETUP 
    int r = (int) radius; 

    // BG WHITE 
    int cx = this.getWidth()/2, cy = this.getHeight()/2; 
    Paint bg_paint = new Paint(); 
    bg_paint.setAntiAlias(true); 
    bg_paint.setARGB(255, 255, 255, 255); 
    ShapeDrawable bg = new ShapeDrawable(new OvalShape()); // If removed, then ArcShape causes the same CNFE error 
    canvas.drawCircle(cx, cy, r, bg_paint); 

    // ROTATING ARC 
    ShapeDrawable drawable = new ShapeDrawable(new ArcShape(-90, s)); 
    drawable.getPaint().setColor(0xff74AC23); 
    drawable.setBounds(cx - (r-2), cy - (r-2), cx + (r-2), cy + (r-2)); 
    drawable.draw(canvas); 

    invalidate(); 
} 

編集：また、私はこれらのコンストラクタを既に用意しています。そうであっても、エラーがまだ発生して：

public ArcButton(Context context, AttributeSet attrs, int defStyle) 
{ 
    super(context, attrs, defStyle); 
} 

public ArcButton(Context context, AttributeSet attrs) 
{ 
    super(context, attrs); 
} 

public ArcButton(Context context) 
{ 
    super(context); 
} 

Answer 1

は、多分あなたはまた、いくつかの違いとクリーンなプロジェクトを持って、私のコードを見つけます。

import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.graphics.drawable.ShapeDrawable; 
import android.graphics.drawable.shapes.ArcShape; 
import android.graphics.drawable.shapes.OvalShape; 
import android.util.AttributeSet; 
import android.view.View; 

public class Button1 extends View 
{ 
    private int radius = 100; 

    /** 
    * @param context 
    * @param attrs 
    */ 
    public Button1(Context context, AttributeSet attrs) 
    { 
     super(context, attrs); 
    } 

    @Override 
    protected void onDraw(Canvas canvas) 
    { 
     super.onDraw(canvas); 

     // SETUP 
     int r = (int) radius ; 

     // BG WHITE 
     int cx = this.getWidth()/2, cy = this.getHeight()/2; 
     Paint bg_paint = new Paint(); 
     bg_paint.setAntiAlias(true); 
     bg_paint.setARGB(255, 255, 255, 255); 
     ShapeDrawable bg = new ShapeDrawable(new OvalShape()); // If removed, then ArcShape causes the same CNFE error 
     canvas.drawCircle(cx, cy, r, bg_paint); 

     // ROTATING ARC 
     ShapeDrawable drawable = new ShapeDrawable(new ArcShape(-90, 60)); 
     drawable.getPaint().setColor(0xff74AC23); 
     drawable.setBounds(cx - (r-2), cy - (r-2), cx + (r-2), cy + (r-2)); 
     drawable.draw(canvas); 

     invalidate(); 
    } 
}