Javaв„ў EE 5 Tutorial, The (3rd Edition)

Let s continue to clean up the TextModel. How good can this get? When I opened the file, here s what the window happened to open on for me:

public void InsertSectionTags() { int cursorLine = LineContainingCursor(); lines.InsertRange(cursorLine+1, NewSection()); selectionStart = NewSelectionStart(cursorLine + 1, "<sect1><title>"); } public ArrayList NewSection() { ArrayList temp = new ArrayList(); temp.Add("<sect1><title></title>"); temp.Add("</sect1>"); return temp; }

That NewSection code is pretty ugly. It s left over from a time earlier in our learning of C#, when we didn t understand arrays and ArrayList very well. I think we can get that down to a data declaration, but let s do it step by step to be sure that we understand how things work. We ll cement our understanding of arrays and ArrayList a bit as well. First, let s create the ArrayList in one step by using a literal string array:

public ArrayList NewSection() { return new ArrayList( new String[] {" < sect1 >< title >< /title > "," < /sect1 > " }); }

That works. Now, why do we need an ArrayList? It looks like InsertRange will take any collection, so let s just return an array of strings:

public string[] NewSection() { return new String[] {" < sect1 >< title >< /title > "," < /sect1 > " }; }

That works just fine also. If that s the case, we should be able to just create that string array as a constant member in the class. We ll make it static, so there will be only one array created. And we ll rename it newSection, because fields are typically lowercase in C#:

public void InsertSectionTags() { int cursorLine = LineContainingCursor(); lines.InsertRange(cursorLine+1, newSection ); selectionStart = NewSelectionStart(cursorLine + 1, "<sect1><title>"); } private static string[] newSection = {" < sect1 >< title >< /title > "," < /sect1 > " };

That works just fine as well. Now we re noticing that the string passed in to the NewSelectionStart looks a lot like the first element of our input array ”but we don t see what would be good to do about it yet. At least I don t. Instead, I m going to make the same change to the InsertParagraphTag method, from

public void InsertParagraphTag() { int cursorLine = LineContainingCursor(); lines.InsertRange(cursorLine+1, NewParagraph()); selectionStart = NewSelectionStart(cursorLine + 1, "<P>"); } public ArrayList NewParagraph() { ArrayList temp = new ArrayList(); temp.Add("<P></P>"); return temp; }

to this:

public void InsertParagraphTag() { int cursorLine = LineContainingCursor(); lines.InsertRange(cursorLine+1, newParagraph ); selectionStart = NewSelectionStart(cursorLine + 1, "<P>"); } private static string[] newParagraph = { " < P >< /P > " };

That works just fine as well. Let s see what still needs improving. The class now looks like this:

using System; using System.Collections; using System.Text; using System.Text.RegularExpressions; namespace Notepad { class TextModel { private static string[] newParagraph = { "<P></P>" }; private static string[] newSection = {"<sect1><title></title>","</sect1>" }; private ArrayList lines; private int selectionStart; public TextModel() { lines = new ArrayList(); } private int LineContainingCursor() { if (lines.Count == 0) return -1; int length = 0; int lineNr = 0; int cr = Environment.NewLine.Length; foreach ( String s in lines) { if (length < = selectionStart && selectionStart < length+s.Length + cr ) break; length += s.Length + cr; lineNr++; } return lineNr; } public ArrayList Lines { get { return lines; } set { lines = value; } } public void SetLines(String[] lines) { this.Lines = new ArrayList(lines); } public String[] LinesArray() { String[] result = new String[lines.Count]; lines.CopyTo(result); return result; } public String TestText { get { StringBuilder b = new StringBuilder(); foreach(String s in lines) { b.Append(s); b.Append(System.Environment.NewLine); } b.Insert(SelectionStart,""); return b.ToString(); } } public int SelectionStart { get { return selectionStart; } set { selectionStart = value; } } public void Enter() { InsertParagraphTag(); } public void InsertParagraphTag() { int cursorLine = LineContainingCursor(); lines.InsertRange(cursorLine+1, newParagraph); selectionStart = NewSelectionStart(cursorLine + 1, " < P > "); } public void AltS() { InsertSectionTags(); } public void InsertSectionTags() { int cursorLine = LineContainingCursor(); lines.InsertRange(cursorLine+1, newSection); selectionStart = NewSelectionStart(cursorLine + 1, " < sect1 >< title > "); } private int NewSelectionStart(int cursorLine, string tags) { return SumLineLengths(cursorLine) + tags.Length; } private int SumLineLengths(int cursorLine) { int length = 0; for (int i = 0; i < cursorLine; i++) length += ((String)lines[i]).Length + Environment.NewLine.Length; return length; } } }