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POWPF StreamWriter error
 

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  1. POWPF StreamWriter error
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    <p>When I want to write a file I get this error:</p> <p>System.ArgumentNullException: Value can't be null. Parameter name: path in System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize, Boolean checkHost) in System.IO.StreamWriter..ctor(String path) in Music_Player.Library.SongList_Save(String fileName) in "MY PATH"</p> <p>This is the code of file writer:</p> <pre><code>private void AddSong(string path) { DataContext = new Song(); Song _songAdd = new Song(); FileInfo _song = new FileInfo(path); _songAdd.SongLengh = MainWindow._MusicPlayer.TransformToTime(MainWindow._MusicPlayer.GetSongMaxLength(path)); _songAdd.SongName = System.IO.Path.GetFileNameWithoutExtension(_song.Name); _songAdd.SongPath = path; LB_SongList.Items.Add(_songAdd); SongList_Save(SelectedPlaylist); } private void LB_SongList_Drop(object sender, DragEventArgs e) { String[] file = e.Data.GetData(DataFormats.FileDrop, true) as String[]; foreach (var path in file) { if (MainWindow._MusicPlayer.GetSongMaxLength(path) != -1) { AddSong(path); } } } public void SongList_Save(String fileName) { try { if (!String.IsNullOrEmpty(fileName) &amp;&amp; File.Exists(fileName)) { using (StreamWriter comboboxsw = new StreamWriter(fileName)) { for (int cfgitem = 0; cfgitem &lt; LB_SongList.Items.Count; cfgitem++) { comboboxsw.WriteLine(GetPath((ListBoxItem)(LB_SongList.ItemContainerGenerator.ContainerFromIndex(cfgitem)))); } comboboxsw.Close(); } } } catch (Exception e) { MessageBox.Show(e.ToString()); } } </code></pre> <p>And if this isn't enough it does write a file, but the text is written twice. //Edit it writes twice but it could be caused by other code so nevermind.</p> <p>New exception: System.ArgumentNullException: Value can't be null. Parameter name: element</p> <p>in MS.Interal.Media.VisualTreeUtils.AsNonNullVisual(DependencyObject element, Visual&amp; visual, Visual3D&amp; visual3D)</p> <p>in System.Windows.Media.VisualTreeHelper.GetChildernCount(DependencyObject reference)</p> <p>in Music_Player.Library.FindVisualChild[childItem](DependencyObject obj) in "MY PATH"</p> <p>in Music_Player.Library.GetPath(ListBoxItem lb) in "MY PATH"</p> <p>in Music_Player.Library.SongList_Save(String fileName) in "MY PATH"</p> <p>All three methods below:</p> <pre><code>private childItem FindVisualChild&lt;childItem&gt;(DependencyObject obj) where childItem : DependencyObject { for (int i = 0; i &lt; VisualTreeHelper.GetChildrenCount(obj); i++) { DependencyObject child = VisualTreeHelper.GetChild(obj, i); if (child != null &amp;&amp; child is childItem) return (childItem)child; else { childItem childOfChild = FindVisualChild&lt;childItem&gt;(child); if (childOfChild != null) return childOfChild; } } return null; } private string GetPath(ListBoxItem lb) { ListBoxItem myListBoxItem = (ListBoxItem)(lb); ContentPresenter myContentPresenter = FindVisualChild&lt;ContentPresenter&gt;(myListBoxItem); DataTemplate myDataTemplate = myContentPresenter.ContentTemplate; Label target = (Label)myDataTemplate.FindName("SongPath", myContentPresenter); return (string)target.Content; } public void SongList_Save(String fileName) { try { if (!String.IsNullOrEmpty(fileName)) { using (StreamWriter comboboxsw = new StreamWriter(fileName)) { for (int cfgitem = 0; cfgitem &lt; LB_SongList.Items.Count; cfgitem++) { comboboxsw.WriteLine(GetPath((ListBoxItem)(LB_SongList.ItemContainerGenerator.ContainerFromIndex(cfgitem)))); } comboboxsw.Close(); } } } catch (Exception e) { MessageBox.Show(e.ToString()); } } </code></pre>
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    1. This table or related slice is empty.
    1. PTQuestion
    1. USKuba Wasilczyk
    1. USKuba Wasilczyk
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
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      1. PTAnswer
    1. This table or related slice is empty.
    1. COEasy one, debug your application and you'll see, that `fileName` is null or empty as the exception already pointed out... ;)
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      1. POWPF StreamWriter error
      1. USDHN
    2. COBut I always define fileName when calling. And it writes the file with the name it should and write 2 same lines.
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      1. POWPF StreamWriter error
      1. USKuba Wasilczyk
    3. COWell the exception is telling otherwise. Check your code.
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      1. USDHN
 

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