Thread: File editing problem

I'm writing a program to dynamically update an xml file to add, delete, and edit entries in the file. I've run into an issue with the add method because when I write into the file, a random letter is added before the line. EX:

I want to add "<item> ..." to the end of the list of entries, but when it is added, this is what is added "Z <item> ..."

The spacing for the <item> is correct, however, I don't see where or why the Z is added.

public static void insertItem(Item i) 
	{
		try {
			String insert = "\t\t<item>";
			String text = "";
			Scanner in = new Scanner(file);
			while(in.hasNext())
			{
				text = text.concat(in.next());
			}
 
			int where = findEnd(text);
 
			insert += "\n\t\t\t<title>" + i.getTitle() + "</title>\n\t\t\t<description>\n\t\t\t" + i.getDesc() + "\n\t\t\t</description>\n\t\t</item>\n";
 
			System.out.println("\n" + insert);
 
			//text = firstPart + insert + secondPart;
 
			//System.out.println("\n" + text);
 
			StringBuffer str = new StringBuffer(text);
			str = str.insert(where, insert);
			//System.out.println(insert);
 
			System.out.println(file.length());
 
			insert(file.getPath(), file.length()-20, insert);
 
			System.out.println(file.length());
 
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			System.out.println("File not found: " + file.getPath());
		} 
 
		//refreshItems();
 
	}
	//Returns the index of the '<' in the </channel> statement
	private static int findEnd(String file)
	{
		int index = file.indexOf("</channel>");
		return index;
	}
public static void insert(String filename, long offset, String content) {
		try {
			RandomAccessFile r = new RandomAccessFile(new File(filename), "rw");
			RandomAccessFile rtemp = new RandomAccessFile(new File(filename + "~"), "rw");
			long fileSize = r.length();
			FileChannel sourceChannel = r.getChannel();
			FileChannel targetChannel = rtemp.getChannel();
			sourceChannel.transferTo(offset, (fileSize - offset), targetChannel);
			sourceChannel.truncate(offset);
			r.seek(offset);
			r.writeUTF(content);
			long newOffset = r.getFilePointer();
			targetChannel.position(0L);
			sourceChannel.transferFrom(targetChannel, newOffset, (fileSize - offset));
			sourceChannel.close();
			targetChannel.close();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

Relevant file contents before the edit:

<item>
			<title>Valentine's Day</title>
			<description>
				The Sophomore Class Cabinet will be selling Valentine's Day Candy
				Grams/Special Packages during all lunches starting February 6th
				until February 12th.
			</description>
		</item>
	</channel>

After

<item>
			<title>Valentine's Day</title>
			<description>
				The Sophomore Class Cabinet will be selling Valentine's Day Candy
				Grams/Special Packages during all lunches starting February 6th
				until February 12th.
			</description>
		</item>
Z              <item>
			<title>chicken</title>
			<description>
				noodle
			</description>
		</item>

Originally Posted by Norm

Is it always the letter Z and in the same location?

Where in the code does the "Z" first appear? Add some debug statements to test all Strings for "Z" and to print that String when it is found.

No, it is not always a Z and it is always in the same location. There isn't anywhere in the code that a random letter like that should show up. Aside from the Item class, all code used in that method is present and posted.

Here is the Item class for future reference, I also do have println statements for debugging active.

XML Editor.zip

Attached is a ZIP file containing all the files in the project, assuming you are using Eclipse, you can right click on the file manager in Eclipse and import the file system after you unzip it. The Class being tested is called "Translator."

Code to run

 
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
import java.util.Scanner;
 
public class Item {
 
	String title;
	String description;
	static String directory = "C:\\Users\\Alex\\workspace\\XML Editor\\"; //change this to the directory where the .xml file is located
	static String name = "test.xml"; //change this to the name of the .xml file
	static File file = new File(directory + name);
	public Item(String title, String description)
	{
		this.title = title;
		this.description = description;
	}
 
	public String getTitle()
	{
		return title;
	}
 
	public String getDesc()
	{
		return description;
	}
 
	public void setDesc(String desc)
	{
		description = desc;
	}
 
	public void setTitle(String title)
	{
		this.title = title;
	}
	public static void insertItem(Item i) 
	{
		try {
			String insert = "\t<item>";
			String text = "";
			Scanner in = new Scanner(file);
			while(in.hasNext())
			{
				text = text.concat(in.next());
			}
 
			int where = findEnd(text);
 
			insert += "\n\t\t\t<title>" + i.getTitle() + "</title>\n\t\t\t<description>\n\t\t\t" + i.getDesc() + "\n\t\t\t</description>\n\t</item>\n";
 
			System.out.println("\n" + insert);
 
			//text = firstPart + insert + secondPart;
 
			//System.out.println("\n" + text);
 
			StringBuffer str = new StringBuffer(text);
			str = str.insert(where, insert);
			//System.out.println(insert);
 
			System.out.println(file.length());
 
			insert(file.getPath(), file.length()-18, insert);
 
			System.out.println(file.length());
 
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			System.out.println("File not found: " + file.getPath());
		} 
 
		//refreshItems();
 
	}
	//Returns the index of the '<' in the </channel> statement
	private static int findEnd(String file)
	{
		int index = file.indexOf("</channel>");
		return index;
	}
 
 
 
	public static void insert(String filename, long offset, String content) {
		try {
			RandomAccessFile r = new RandomAccessFile(new File(filename), "rw");
			RandomAccessFile rtemp = new RandomAccessFile(new File(filename + "~"), "rw");
			long fileSize = r.length();
			FileChannel sourceChannel = r.getChannel();
			FileChannel targetChannel = rtemp.getChannel();
			sourceChannel.transferTo(offset, (fileSize - offset), targetChannel);
			sourceChannel.truncate(offset);
			r.seek(offset);
			r.writeUTF(content);
			long newOffset = r.getFilePointer();
			targetChannel.position(0L);
			sourceChannel.transferFrom(targetChannel, newOffset, (fileSize - offset));
			sourceChannel.close();
			targetChannel.close();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
 
	public static void main(String[] args)
	{
		insertItem(new Item("chicken", "noodle"));
	}
 
}

test .xml file

<rss xmlns:media="www.hardytechsolutions.com" version="2.0">
	<channel>
		<title>BMHS Daily Announcements</title>
		<link />
		<description>Daily Announcements displayed on TV's</description>
		<language>en-US</language>
		<copyright>Copyright (c) 2013 William Hardy</copyright>
		<pubDate>Tue, 03 Dec 2013 07:05:52 -0500</pubDate>
		<ttl>1</ttl>
		<item>
			<title>Library Reservations</title>
			<description>
				Period 7 (9:00-10:10 am) reserved ~ OPEN with limited
				access, Period 5
				(12:08–1:42 pm) reserved ~ OPEN with limited access,
				After School ~
				CLOSED for Math Power Hour.
			</description>
		</item>
		<item>
			<title>Math Power Hour</title>
			<description>
				this week will take place today from 3:15 to 4:15 in the
				school library.
			</description>
		</item>
		<item>
			<title>Senior Retreat</title>
			<description>
				Your retreat is tomorrow! Please arrive to the Fine Arts
				Gym by 8am.
				Dress for the day is casual, but you need to wear your
				senior
				t-shirt.
			</description>
		</item>
		<item>
			<title>Saturday Detention</title>
			<description>
				This Saturday, 2/8/14, is a scheduled Saturday
				Detention. Reminder
				emails have been sent to student email accounts
				and to parents.
			</description>
		</item>
		<item>
			<title>CPR and First Aid</title>
			<description>
				There will be CPR and First Aid classes offered
				Wednesday, February 5 and
				Monday, February 24. The classes will be in
				Room 201 and will start
				promptly at 3:30.
			</description>
		</item>
		<item>
			<title>Student Tech Club</title>
			<description>
				Bishop McNamara is looking for students who are
				interested in how
				technology influences their lives. Please contact
				Ms. Auchmoody or
				Mr. Buckley.
			</description>
		</item>
		<item>
			<title>Passport Future</title>
			<description>
				Seniors, please remember to apply for the Passport to
				the Future Award.
				Essays are due to Mr. Pozniak or Mr. Williams by
				Feb. 6th.
			</description>
		</item>
		<item>
			<title>Boys' Lacrosse</title>
			<description>
				There will be a parents meeting for all boys' lacrosse
				players on Monday,
				February 10.
			</description>
		</item>
		<item>
			<title>Music Trip</title>
			<description>
				It is time to sign up for your Hotel Rooms for the
				Chicago Trip.
			</description>
		</item>
		<item>
			<title>Guidance counselors</title>
			<description>
				will be visiting your English classrooms on Monday and
				Tuesday, February
				10 and 11, to distribute the 2014-2015 Course
				Bulletin booklets and
				Course Selection Sheets.
			</description>
		</item>
		<item>
			<title>Talent Show</title>
			<description>
				practice will be today from 3:15 to 4:30. Please be on
				time in room 218.
			</description>
		</item>
		<item>
			<title>Engineering Club</title>
			<description>
				will not be meeting this week. Robotics team needs to
				start work on
				RobotC as soon as possible.
			</description>
		</item>
		<item>
			<title>Adventure Sports Club</title>
			<description>
				is meeting today promptly at 3:15 in Room 108. We will
				be talking
				about our next two trips so please be on time.
			</description>
		</item>
		<item>
			<title>Honors Global Studies</title>
			<description>
				Applications are now available on the BMHS website under
				"Academics/Course
				Bulletin."
			</description>
		</item>
		<item>
			<title>Missing Camera</title>
			<description>
				We need assistance in locating a Black, Nikon camera
				with a Silver and
				Black case that has Nikon written on the front.
			</description>
		</item>
		<item>
			<title>Valentine's Day</title>
			<description>
				The Sophomore Class Cabinet will be selling Valentine's
				Day Candy
				Grams/Special Packages during all lunches starting February
				6th
				until February 12th.
			</description>
		</item>
	</channel>
</rss>

All the changes are made at the bottom of the file.

<rss xmlns:media="www.hardytechsolutions.com" version="2.0">
	<channel>
		<title>BMHS Daily Announcements</title>
		<link />
		<description>Daily Announcements displayed on TV's</description>
		<language>en-US</language>
		<copyright>Copyright (c) 2013 William Hardy</copyright>
		<pubDate>Tue, 03 Dec 2013 07:05:52 -0500</pubDate>
		<ttl>1</ttl>
		<item>
			<title>Library Reservations</title>
			<description>
				Period 7 (9:00-10:10 am) reserved ~ OPEN with limited
				access, Period 5
				(12:08–1:42 pm) reserved ~ OPEN with limited access,
				After School ~
				CLOSED for Math Power Hour.
			</description>
		</item>
		<item>
			<title>Math Power Hour</title>
			<description>
				this week will take place today from 3:15 to 4:15 in the
				school library.
			</description>
		</item>
</channel>
</rss>

The -18 is the offset from the end of the file to put the addition inside the <channel> element.

technically, this should work.

this week will take place today from 3:15 to 4:15 in the
				school library.
			</description>
		</item>
</channel>
</rss>

The addition should appear right after the </item> line