我正在从Android Studio的模板构建登录屏幕，但布局不会预览。它说：
Rendering Problems Exception raised during rendering: String index out of range: 0 (Details)
详情包括：
java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(String.java:686)
at com.android.internal.util.XmlUtils_Delegate.convertValueToInt(XmlUtils_Delegate.java:47)
at com.android.internal.util.XmlUtils.convertValueToInt(XmlUtils.java:88)
at android.content.res.BridgeTypedArray.getInt(BridgeTypedArray.java:204)
at android.widget.TextView.<init>(TextView.java:1051)
at android.widget.EditText.<init>(EditText.java:65)
at android.widget.EditText.<init>(EditText.java:61)
at android.widget.EditText.<init>(EditText.java:57)
at sun.reflect.GeneratedConstructorAccessor237.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at android.view.LayoutInflater.createView(LayoutInflater.java:607)
at android.view.BridgeInflater.onCreateView(BridgeInflater.java:93)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:682)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:741)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:138)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:806)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:782)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:809)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:782)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:809)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:782)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:809)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:782)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:385)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:413)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:321)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:350)
at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:510)
at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:498)
at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:888)
at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:498)
at com.android.tools.idea.rendering.RenderTask.access$600(RenderTask.java:72)
at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:610)
at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:607)
at com.android.tools.idea.rendering.RenderService.runRenderAction(RenderService.java:366)
at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:607)
at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:629)
at com.intellij.android.designer.designSurface.AndroidDesignerEditorPanel$6.run(AndroidDesignerEditorPanel.java:480)
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$1.run(Alarm.java:351)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
代码中的某些EditText看起来有问题。我有两个用户名，第二个用于密码。
这是布局的XML代码：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:gravity="center_horizontal"
android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin" tools:context=".LoginActivity">
<!-- Login progress -->
<ProgressBar android:id="@+id/login_progress" style="?android:attr/progressBarStyleLarge"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_marginBottom="8dp" android:visibility="gone" />
<ScrollView android:id="@+id/login_form" android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout android:id="@+id/email_login_form" android:layout_width="match_parent"
android:layout_height="wrap_content" android:orientation="vertical">
<ImageView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:src="@drawable/hs_logo" />
<android.support.design.widget.TextInputLayout android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText android:id="@+id/email" android:layout_width="match_parent"
android:layout_height="wrap_content" android:hint="Username"
android:imeActionId="@+id/login"
android:imeActionLabel="@string/action_sign_in_short"
android:imeOptions="actionUnspecified" android:inputType="text"
android:maxLines="1" android:singleLine="true" />
</android.support.design.widget.TextInputLayout>
<android.support.design.widget.TextInputLayout android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText android:id="@+id/password" android:layout_width="match_parent"
android:layout_height="wrap_content" android:hint="@string/prompt_password"
android:imeActionId="@+id/login"
android:imeActionLabel="@string/action_sign_in_short"
android:imeOptions="actionUnspecified" android:inputType="textPassword"
android:maxLines="1" android:singleLine="true" />
</android.support.design.widget.TextInputLayout>
<Button android:id="@+id/email_sign_in_button" style="?android:textAppearanceSmall"
android:layout_width="match_parent" android:layout_height="wrap_content"
android:layout_marginTop="16dp" android:text="@string/action_sign_in"
android:textStyle="bold" />
</LinearLayout>
</ScrollView>
</LinearLayout>
解决这个问题需要一个小时。