我试图创建我的第一个自定义视图的子类 GraphView ，并把它添加到我的布局XML文件中。

我发现这太问题并试图把它应用到我的项目，但有些事情似乎是错误的，因为Eclipse IDE的告诉我：

  de.muza3000.graph.GraphView失败的实例。 

和抛出异常：

  java.lang.NoSuchMethodException：de.muza3000.graph.GraphView＆LT;＆初始化GT;（android.content.Context，android.util.AttributeSet）在java.lang.Class.getConstructor0（来源不明）在java.lang.Class.getConstructor（来源不明）在com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass（来源不明）在com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView（来源不明）在android.view.BridgeInflater.loadCustomView（BridgeInflater.java:198）在android.view.BridgeInflater.createViewFromTag（BridgeInflater.java:126）在android.view.LayoutInflater.rInflate（LayoutInflater.java:618）在android.view.LayoutInflater.inflate（LayoutInflater.java:407）在android.view.LayoutInflater.inflate（LayoutInflater.java:296）在com.android.layoutlib.bridge.Bridge.computeLayout（Bridge.java:396）在com.android.ide.common.rendering.LayoutLibrary.createLegacySession（LayoutLibrary.java:382）在com.android.ide.common.rendering.LayoutLibrary.createSession（LayoutLibrary.java:276）在com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(Unknown资源）在com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(Unknown资源）在com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout（来源不明）在com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.activated（来源不明）在com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditor.pageChange（来源不明）在org.eclipse.ui.part.MultiPageEditorPart $ 2.widgetSelected（MultiPageEditorPart.java:290）在org.eclipse.swt.widgets.TypedListener.handleEvent（TypedListener.java:234）在org.eclipse.swt.widgets.EventTable.sendEvent（EventTable.java:84）在org.eclipse.swt.widgets.Widget.sendEvent（Widget.java:1053）在org.eclipse.swt.widgets.Widget.sendEvent（Widget.java:1077）在org.eclipse.swt.widgets.Widget.sendEvent（Widget.java:1062）在org.eclipse.swt.widgets.Widget.notifyListeners（Widget.java:774）在org.eclipse.swt.custom.CTabFolder.setSelection（CTabFolder.java:2743）在org.eclipse.swt.custom.CTabFolder.onMouse（CTabFolder.java:1429）在org.eclipse.swt.custom.CTabFolder $ 1.handleEvent（CTabFolder.java:257）在org.eclipse.swt.widgets.EventTable.sendEvent（EventTable.java:84）在org.eclipse.swt.widgets.Widget.sendEvent（Widget.java:1053）在org.eclipse.swt.widgets.Display.runDeferredEvents（Display.java:4066）在org.eclipse.swt.widgets.Display.readAndDispatch（Display.java:3657）在org.eclipse.ui.internal.Workbench.runEventLoop（Workbench.java:2640）在org.eclipse.ui.internal.Workbench.runUI（Workbench.java:2604）在org.eclipse.ui.internal.Workbench.access $ 4（Workbench.java:2438）在org.eclipse.ui.internal.Workbench $ 7.run（Workbench.java:671）在org.eclipse.core.databinding.observable.Realm.runWithDefault（Realm.java:332）在org.eclipse.ui.internal.Workbench.createAndRunWorkbench（Workbench.java:664）在org.eclipse.ui.PlatformUI.createAndRunWorkbench（PlatformUI.java:149）在org.eclipse.ui.internal.ide.application.IDEApplication.start（IDEApplication.java:115）在org.eclipse.equinox.internal.app.EclipseAppHandle.run（EclipseAppHandle.java:196）在org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)在org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start（EclipseAppLauncher.java:79）在org.eclipse.core.runtime.adaptor.EclipseStarter.run（EclipseStarter.java:369）在org.eclipse.core.runtime.adaptor.EclipseStarter.run（EclipseStarter.java:179）在sun.reflect.NativeMethodAccessorImpl.invoke0（本机方法）在sun.reflect.NativeMethodAccessorImpl.invoke（来源不明）在sun.reflect.DelegatingMethodAccessorImpl.invoke（来源不明）在java.lang.reflect.Method.invoke（来源不明）在org.eclipse.equinox.launcher.Main.invokeFramework（Main.java:619）在org.eclipse.equinox.launcher.Main.basicRun（Main.java:574）在org.eclipse.equinox.launcher.Main.run（Main.java:1407） 

下面是我的布局：

 ＆LT;？XML版本=1.0编码=UTF-8＆GT？;＆LT; LinearLayout中的xmlns：机器人=htt​​p://schemas.android.com/apk/res/android        机器人：方向=垂直        机器人：layout_width =FILL_PARENT        机器人：layout_height =FILL_PARENT＆GT;    ＆LT;的TextView        机器人：layout_width =FILL_PARENT        机器人：layout_height =WRAP_CONTENT        机器人：文字=@字符串/你好/＆GT;    ＆LT; de.muza3000.graph.GraphView        机器人：layout_width =FILL_PARENT/＆GT;＆LT; / LinearLayout中＆GT; 

和我的code：

 包de.muza3000.graph;进口android.content.Context;进口android.util.AttributeSet;进口android.view.View;公共类GraphView扩展视图{    GraphView（上下文的背景下，ATTRS的AttributeSet，INT defStyle）    {        超（背景下，ATTRS，defStyle）;    }    GraphView（上下文的背景下，ATTRS的AttributeSet）    {        超（背景下，ATTRS）;    }    GraphView（上下文的背景下）    {        超级（上下文）;    }} 

解决方案

构造函数的访问修饰符更改为公众。

I'm trying to create my first custom View subclass GraphView and add it to my layout XML file.

I found this SO question and tried to apply it to my project, but something seems to be wrong because Eclipse IDE tells me:

de.muza3000.graph.GraphView failed to instantiate.

and throws an exception:

java.lang.NoSuchMethodException: de.muza3000.graph.GraphView.<init>(android.content.Context, android.util.AttributeSet)
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(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:618)
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:396)
at com.android.ide.common.rendering.LayoutLibrary.createLegacySession(LayoutLibrary.java:382)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:276)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(Unknown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(Unknown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(Unknown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.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:290)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:234)
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:2743)
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:1429)
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:4066)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3657)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2640)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2604)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115)
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:369)
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:619)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574)
at org.eclipse.equinox.launcher.Main.run(Main.java:1407)

Here is my layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
    <TextView  
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        android:text="@string/hello"/>
    <de.muza3000.graph.GraphView 
        android:layout_width="fill_parent"/>
</LinearLayout>

And my code:

package de.muza3000.graph;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;

public class GraphView extends View {


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


    GraphView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
    }

    GraphView(Context context)
    {
        super(context);
    }

}

Change the access modifier of the constructors to public.