嗨，这是我的C＃代码获取idexoutofrange异常我可能知道如何解决它 [英] Hi here is my C# code getting idexoutofrange exception may I know how to fix it

问题描述

private void ShowOldMedicalNoteCommandHandler()
      {
          if (null != this.MedicalElements)
          {
              NavigatedIndex = NavigatedIndex + 1;
              var medicalNote = MedicalElements[NavigatedIndex];
              NavigateMedicalNote(medicalNote);
              IsNewestEnabled = true;
              IsOldestEnabled = MedicalElements.Count - 1 != NavigatedIndex;
          }
      }

我的尝试：

What I have tried:

private void ShowOldMedicalNoteCommandHandler()
      {
          if (null != this.MedicalElements)
          {
              NavigatedIndex = NavigatedIndex + 1;
              var medicalNote = MedicalElements[NavigatedIndex];
              NavigateMedicalNote(medicalNote);
              IsNewestEnabled = true;
              IsOldestEnabled = MedicalElements.Count - 1 != NavigatedIndex;
          }
      }

推荐答案

显然 NavigatedIndex 是大于 MedicalElements.Count 所以只需检查一下：

Obviously NavigatedIndex is greater than the MedicalElements.Count so just check for it:

...
NavigatedIndex = NavigatedIndex + 1;
if(NavigatedIndex < MedicalElements.Count)
{
   var medicalNote = MedicalElements[NavigatedIndex];
   NavigateMedicalNote(medicalNote);
   IsNewestEnabled = true;
   IsOldestEnabled = MedicalElements.Count - 1 != NavigatedIndex;
}
else
{
 // handle this case accordingly 
}

显然，错误源于：

Apparently, the mistake stems from:

MedicalElements[NavigatedIndex]

当值为

when the value of

NavigatedIndex

大于

is greater than the number of items in

MedicalElements

中的项目数减一，不要忘记像数组一样的集合中的索引零。要防止这种情况发生，请使用计数 [ ^ ]。

minus one, not to forget indices in a collection like array start from zero. To prevent this, use Count [^].

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