我一直在Android上试用自定义视图。我建立了一个视图，但是当我将视图添加到我的活动XML时，它给了我这个错误：
The following classes could not be initialized:
- com.Schnackel.trialapp.RoomView
如果从RoomView XML中删除<com.Schnackel.trialapp.RoomView部分，我可以从自定义类设计窗口中删除错误，但错误仍显示在我的活动设计窗口中。我根本没有搞过RoomView类。它有三个初始化方法包括public RoomView(Context context, AttributeSet attrs)，我看到几个问题设置为答案。我尝试重新启动Android Studio并清理项目。该应用程序确实在我的设备上构建和运行，但是当我尝试与它进行交互时，它会崩溃。我看了很多问题，但找不到帮我解决这个问题的问题。如果您需要更多信息，请与我们联系。
这里是编辑时的堆栈跟踪：
java.lang.ClassNotFoundException: com.Schnackel.trialapp.R$styleable
at org.jetbrains.android.uipreview.ProjectClassLoader.load(ProjectClassLoader.java:94)
at com.android.tools.idea.rendering.RenderClassLoader.findClass(RenderClassLoader.java:56)
at org.jetbrains.android.uipreview.ProjectClassLoader.findClass(ProjectClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at com.Schnackel.trialapp.RoomView.init(RoomView.java:50)
at com.Schnackel.trialapp.RoomView.<init>(RoomView.java:38)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:375)
at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:100)
at com.android.tools.idea.rendering.LayoutlibCallback.loadView(LayoutlibCallback.java:172)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:206)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:131)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:755)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:758)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:758)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:373)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:393)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:337)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:332)
at com.android.tools.idea.rendering.RenderService$3.compute(RenderService.java:575)
at com.android.tools.idea.rendering.RenderService$3.compute(RenderService.java:564)
at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:932)
at com.android.tools.idea.rendering.RenderService.createRenderSession(RenderService.java:564)
at com.android.tools.idea.rendering.RenderService.render(RenderService.java:691)
at com.intellij.android.designer.designSurface.AndroidDesignerEditorPanel$6.run(AndroidDesignerEditorPanel.java:483)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:327)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
RoomView XML：
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:padding="5dp"
android:background="@color/RoomColor"
android:divider="@color/Black">
<com.Schnackel.trialapp.RoomView
android:background="#ccc"
android:layout_width="300dp"
android:layout_height="300dp"
android:paddingLeft="20dp"
android:paddingBottom="40dp"
app:exampleDimension="24sp"
app:exampleColor="#33b5e5"
app:exampleString="Hello, RoomView"
app:exampleDrawable="@android:drawable/ic_menu_add" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="4"
android:text="@string/menu_save"
android:background="@color/SGreyer"
android:textColor="@color/White"
android:id="@+id/roomName"
android:layout_margin="3dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="3"
android:text="@string/menu_save"
android:background="@color/SGreyer"
android:textColor="@color/White"
android:id="@+id/roomArea"
android:layout_margin="3dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="2"
android:text="@string/menu_save"
android:background="@color/SGreyer"
android:textColor="@color/White"
android:id="@+id/roomWatts"
android:layout_margin="3dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/menu_save"
android:background="@color/SGreyer"
android:textColor="@color/White"
android:id="@+id/roomUsage"
android:layout_margin="3dp" />
</LinearLayout>
RoomView类：
package com.Schnackel.trialapp;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.view.View;
/**
* TODO: document your custom view class.
*/
public class RoomView extends View {
private String mExampleString; // TODO: use a default from R.string...
private int mExampleColor = Color.RED; // TODO: use a default from R.color...
private float mExampleDimension = 0; // TODO: use a default from R.dimen...
private Drawable mExampleDrawable;
private TextPaint mTextPaint;
private float mTextWidth;
private float mTextHeight;
public RoomView(Context context)
{
super(context);
if(!isInEditMode())
init(null, 0);
}
public RoomView(Context context, AttributeSet attrs)
{
super(context, attrs);
init(attrs, 0);
}
public RoomView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
if(!isInEditMode())
init(attrs, defStyle);
}
private void init(AttributeSet attrs, int defStyle) {
// Load attributes
final TypedArray a = getContext().obtainStyledAttributes(
attrs, R.styleable.RoomView, defStyle, 0);
mExampleString = a.getString(
R.styleable.RoomView_exampleString);
mExampleColor = a.getColor(
R.styleable.RoomView_exampleColor,
mExampleColor);
// Use getDimensionPixelSize or getDimensionPixelOffset when dealing with
// values that should fall on pixel boundaries.
mExampleDimension = a.getDimension(
R.styleable.RoomView_exampleDimension,
mExampleDimension);
if (a.hasValue(R.styleable.RoomView_exampleDrawable)) {
mExampleDrawable = a.getDrawable(
R.styleable.RoomView_exampleDrawable);
mExampleDrawable.setCallback(this);
}
a.recycle();
// Set up a default TextPaint object
mTextPaint = new TextPaint();
mTextPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
mTextPaint.setTextAlign(Paint.Align.LEFT);
// Update TextPaint and text measurements from attributes
invalidateTextPaintAndMeasurements();
}
private void invalidateTextPaintAndMeasurements() {
mTextPaint.setTextSize(mExampleDimension);
mTextPaint.setColor(mExampleColor);
mTextWidth = mTextPaint.measureText(mExampleString);
Paint.FontMetrics fontMetrics = mTextPaint.getFontMetrics();
mTextHeight = fontMetrics.bottom;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// TODO: consider storing these as member variables to reduce
// allocations per draw cycle.
int paddingLeft = getPaddingLeft();
int paddingTop = getPaddingTop();
int paddingRight = getPaddingRight();
int paddingBottom = getPaddingBottom();
int contentWidth = getWidth() - paddingLeft - paddingRight;
int contentHeight = getHeight() - paddingTop - paddingBottom;
// Draw the text.
canvas.drawText(mExampleString,
paddingLeft + (contentWidth - mTextWidth) / 2,
paddingTop + (contentHeight + mTextHeight) / 2,
mTextPaint);
// Draw the example drawable on top of the text.
if (mExampleDrawable != null) {
mExampleDrawable.setBounds(paddingLeft, paddingTop,
paddingLeft + contentWidth, paddingTop + contentHeight);
mExampleDrawable.draw(canvas);
}
}
/**
* Gets the example string attribute value.
* @return The example string attribute value.
*/
public String getExampleString()
{
return mExampleString;
}
/**
* Sets the view's example string attribute value. In the example view, this string
* is the text to draw.
* @param exampleString The example string attribute value to use.
*/
public void setExampleString(String exampleString) {
mExampleString = exampleString;
invalidateTextPaintAndMeasurements();
}
/**
* Gets the example color attribute value.
* @return The example color attribute value.
*/
public int getExampleColor() {
return mExampleColor;
}
/**
* Sets the view's example color attribute value. In the example view, this color
* is the font color.
* @param exampleColor The example color attribute value to use.
*/
public void setExampleColor(int exampleColor) {
mExampleColor = exampleColor;
invalidateTextPaintAndMeasurements();
}
/**
* Gets the example dimension attribute value.
* @return The example dimension attribute value.
*/
public float getExampleDimension() {
return mExampleDimension;
}
/**
* Sets the view's example dimension attribute value. In the example view, this dimension
* is the font size.
* @param exampleDimension The example dimension attribute value to use.
*/
public void setExampleDimension(float exampleDimension) {
mExampleDimension = exampleDimension;
invalidateTextPaintAndMeasurements();
}
/**
* Gets the example drawable attribute value.
* @return The example drawable attribute value.
*/
public Drawable getExampleDrawable() {
return mExampleDrawable;
}
/**
* Sets the view's example drawable attribute value. In the example view, this drawable is
* drawn above the text.
* @param exampleDrawable The example drawable attribute value to use.
*/
public void setExampleDrawable(Drawable exampleDrawable) {
mExampleDrawable = exampleDrawable;
}
}
P.S。为了将来参考，我应该使用android.stackexchange.com来解决这些问题吗？ x-post是不赞成的？