Java 非平凡（看似）StringIndexOutOfBoundsException

我们的崩溃日志系统显示了一个崩溃，我不明白它是怎么发生的。用户输入未知。我已经添加了日志记录，但结果只有在下一个版本发布后才能看到，大约2周

下面的代码如何引发下一个异常：

Crashes with java.lang.StringIndexOutOfBoundsException length=0; index=1

不是因为并发问题吗？换句话说，它崩溃的情况可能是什么，以及如何避免它（不将它包装到

try catch

）中？如果是并发性问题（我没有看到，但可能我错了），会是什么情况

在过去的一周里，7台设备上发生了约100起故障

这是堆栈跟踪

  Fatal Exception: java.lang.StringIndexOutOfBoundsException: length=0; index=1
  at java.lang.String.substring(String.java:1971)
  at my.app.model.Contact.getFirstSymbol(Contact.java:256)
  at my.app.ui.AvatarView.bind(AvatarView.java:73)
  at my.app.viewholder.CallLogViewHolder.bind(CallLogViewHolder.java:50)
  at my.app.viewholder.CallLogViewHolder.bind(CallLogViewHolder.java:23)
  at my.app.ContactListAdapter.onBindViewHolder(ContactListAdapter.java:68)
  at my.app.ContactListAdapter.onBindViewHolder(ContactListAdapter.java:25)
  at androidx.recyclerview.widget.RecyclerView$Adapter.onCreateViewHolder(RecyclerView.java:6781)
  at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
  at androidx.recyclerview.widget.RecyclerView$Adapter.getItemCount(RecyclerView.java:6781)
  at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
  at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
  at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
  at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
  at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
  at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
  at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
  at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
  at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
  at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
  at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3641)
  at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4194)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at androidx.viewpager.widget.ViewPager.onLayout(ViewPager.java:1775)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:142)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.findFirstDependency(HeaderScrollingViewBehavior.java:142)
  at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:41)
  at com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1556)
  at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:888)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:142)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.findFirstDependency(HeaderScrollingViewBehavior.java:142)
  at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:41)
  at com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1556)
  at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:888)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
  at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
  at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at com.android.internal.policy.DecorView.onLayout(DecorView.java:955)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3092)
  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2779)
  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1863)
  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:8072)
  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911)
  at android.view.Choreographer.doCallbacks(Choreographer.java:723)
  at android.view.Choreographer.doFrame(Choreographer.java:658)
  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897)
  at android.os.Handler.handleCallback(Handler.java:790)
  at android.os.Handler.dispatchMessage(Handler.java:99)
  at android.os.Looper.loop(Looper.java:164)
  at android.app.ActivityThread.main(ActivityThread.java:7000)
  at java.lang.reflect.Method.invoke(Method.java)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:441)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)

---

这里没有线程安全/并发问题。此方法可能与其他线程共享的唯一值是

contactName

的值。这是一个

字符串

引用<代码>字符串是不可变的。此方法从（可能）共享的不可变

字符串

派生的其他值都是线程限制的

除此之外，我感到困惑。

trim

应删除任何与

\s+

匹配的前导或尾随字符。还有

！isEmpty

guard消除了空字符串的可能性。因此，

部分

数组应该至少有一个元素，第一个元素应该至少有一个字符

但例外情况似乎有所不同

因此，人们通常会认为“另类”解释是荒谬的：

• 这可能发生在JIT编译器损坏的平台上
• 这可能是发生在

  字符串

  或

  模式

  中有缺陷的平台上
• 可能是硬件问题
• 可能有一个版本的应用程序，其编译代码与您正在查看的源代码不匹配

---

这些“另类”解释都没有给你任何前进的方向。因此，如果您找不到更好的解释，我建议您使用

try{…}catch

来包围这段有问题的代码，并尝试记录触发问题的

contactName

字符串的长度和内容。在下一个版本中包括这一点，如果/当您开始出现故障时，请准备发布一个带有真正修复的小版本。或者，将其视为用户输入了一个空联系人姓名。。。或者类似的。

什么是

fieldString

的

value

，您能提供一些示例输入吗？我不确定您的问题是否可以重现。所以，你应该给我们这些发生的输入。你可以很容易地找出导致问题的输入是什么。修改代码以1）捕获异常，2）打印出

trimmed

，3）重新显示异常。或设置一个断点。@ArunKumarMN，你确定这就是上面的代码吗？我有这样一个测试，它通过了。@AkashShah，您缺少if（！TextUtils.isEmpty（trimmed））条件。这基本上是返回str==null | | str.length（）==0。如果您添加它，它将通过。下面是一个例子：是的，我对代码的正确性有同样的推理，只是想确定一下。谢谢，如果smbd出现类似问题，我们将等待一两天，但这看起来是答案。

  Fatal Exception: java.lang.StringIndexOutOfBoundsException: length=0; index=1
  at java.lang.String.substring(String.java:1971)
  at my.app.model.Contact.getFirstSymbol(Contact.java:256)
  at my.app.ui.AvatarView.bind(AvatarView.java:73)
  at my.app.viewholder.CallLogViewHolder.bind(CallLogViewHolder.java:50)
  at my.app.viewholder.CallLogViewHolder.bind(CallLogViewHolder.java:23)
  at my.app.ContactListAdapter.onBindViewHolder(ContactListAdapter.java:68)
  at my.app.ContactListAdapter.onBindViewHolder(ContactListAdapter.java:25)
  at androidx.recyclerview.widget.RecyclerView$Adapter.onCreateViewHolder(RecyclerView.java:6781)
  at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
  at androidx.recyclerview.widget.RecyclerView$Adapter.getItemCount(RecyclerView.java:6781)
  at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
  at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
  at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
  at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
  at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
  at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
  at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
  at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
  at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
  at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
  at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3641)
  at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4194)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at androidx.viewpager.widget.ViewPager.onLayout(ViewPager.java:1775)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:142)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.findFirstDependency(HeaderScrollingViewBehavior.java:142)
  at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:41)
  at com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1556)
  at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:888)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:142)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.findFirstDependency(HeaderScrollingViewBehavior.java:142)
  at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:41)
  at com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1556)
  at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:888)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
  at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
  at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
  at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
  at com.android.internal.policy.DecorView.onLayout(DecorView.java:955)
  at android.view.View.layout(View.java:20964)
  at android.view.ViewGroup.layout(ViewGroup.java:6440)
  at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3092)
  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2779)
  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1863)
  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:8072)
  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911)
  at android.view.Choreographer.doCallbacks(Choreographer.java:723)
  at android.view.Choreographer.doFrame(Choreographer.java:658)
  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897)
  at android.os.Handler.handleCallback(Handler.java:790)
  at android.os.Handler.dispatchMessage(Handler.java:99)
  at android.os.Looper.loop(Looper.java:164)
  at android.app.ActivityThread.main(ActivityThread.java:7000)
  at java.lang.reflect.Method.invoke(Method.java)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:441)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)