diff --git a/src/fr/devinsy/sikevadb/filetree/FileTreeSikevaDB.java b/src/fr/devinsy/sikevadb/filetree/FileTreeSikevaDB.java
index 1276be2..ddd8d13 100644
--- a/src/fr/devinsy/sikevadb/filetree/FileTreeSikevaDB.java
+++ b/src/fr/devinsy/sikevadb/filetree/FileTreeSikevaDB.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2013-2017 Christian Pierre MOMON <christian.momon@devinsy.fr>
+ * Copyright (C) 2013-2018 Christian Pierre MOMON <christian.momon@devinsy.fr>
  * 
  * This file is part of SikevaDB, simple key value database.
  * 
@@ -32,6 +32,7 @@ import fr.devinsy.sikevadb.core.Element;
 import fr.devinsy.sikevadb.core.Elements;
 import fr.devinsy.sikevadb.core.SikevaDB;
 import fr.devinsy.sikevadb.core.SikevaDBException;
+import fr.devinsy.sikevadb.core.UnopenedDatabaseException;
 import fr.devinsy.util.strings.StringList;
 
 /**
@@ -83,121 +84,79 @@ public class FileTreeSikevaDB implements SikevaDB
 		this.journalizer = null;
 	}
 
-	/**
-	 * @throws IOException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#clear()
 	 */
 	@Override
 	public void clear() throws SikevaDBException
 	{
-		try
+		if (this.status == Status.CLOSED)
 		{
-			// TODO journalize("clear database");
-
-			FileUtils.deleteDirectory(this.dataDirectory);
-			this.dataDirectory.mkdir();
-		}
-		catch (IOException exception)
-		{
-			this.logger.error("Error clearing database", exception);
-			throw new SikevaDBException("Error clearing database", exception);
-		}
-	}
-
-	/**
-	 * 
-	 */
-	@Override
-	public void close()
-	{
-		this.journalizer = null;
-
-		this.status = Status.CLOSED;
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * 
-	 */
-	@Override
-	public long countOfElements()
-	{
-		long result;
-
-		File[] topFiles = this.dataDirectory.listFiles();
-
-		result = 0;
-		for (File file : topFiles)
-		{
-			if (file.isDirectory())
-			{
-				File[] subFiles = file.listFiles();
-				result += subFiles.length;
-			}
-			else
-			{
-				result += 1;
-			}
-		}
-
-		//
-		return result;
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * 
-	 */
-	@Override
-	public long countOfElements(final String key)
-	{
-		long result;
-
-		if (key == null)
-		{
-			throw new IllegalArgumentException("Null key detected.");
+			throw new UnopenedDatabaseException();
 		}
 		else
 		{
-			File targetDirectory = new File(this.dataDirectory, key);
-			File[] subFiles = targetDirectory.listFiles();
+			try
+			{
+				// TODO journalize("clear database");
 
-			if (subFiles == null)
-			{
-				result = 1;
+				FileUtils.deleteDirectory(this.dataDirectory);
+				this.dataDirectory.mkdir();
 			}
-			else
+			catch (IOException exception)
 			{
-				result = subFiles.length;
+				this.logger.error("Error clearing database", exception);
+				throw new SikevaDBException("Error clearing database", exception);
 			}
 		}
-
-		//
-		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#close()
 	 */
 	@Override
-	public long countOfElements(final String key, final String subkey)
+	public void close() throws UnopenedDatabaseException
 	{
-		long result;
-
-		if ((key == null) || (subkey == null))
+		if (this.status == Status.CLOSED)
 		{
-			throw new IllegalArgumentException("Null key detected [key=" + key + "][subkey=" + subkey + "].");
+			throw new UnopenedDatabaseException();
 		}
 		else
 		{
-			File targetDirectory = new File(this.dataDirectory, key);
-			File targetFile = new File(targetDirectory, subkey);
-			if (targetFile.exists())
+			this.journalizer = null;
+
+			this.status = Status.CLOSED;
+		}
+	}
+
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#countOfElements()
+	 */
+	@Override
+	public long countOfElements() throws UnopenedDatabaseException
+	{
+		long result;
+
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else
+		{
+			File[] topFiles = this.dataDirectory.listFiles();
+
+			result = 0;
+			for (File file : topFiles)
 			{
-				result = 1;
-			}
-			else
-			{
-				result = 0;
+				if (file.isDirectory())
+				{
+					File[] subFiles = file.listFiles();
+					result += subFiles.length;
+				}
+				else
+				{
+					result += 1;
+				}
 			}
 		}
 
@@ -205,60 +164,155 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#countOfElements(java.lang.String)
+	 */
+	@Override
+	public long countOfElements(final String key) throws UnopenedDatabaseException
+	{
+		long result;
+
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else
+		{
+			if (key == null)
+			{
+				throw new IllegalArgumentException("Null key detected.");
+			}
+			else
+			{
+				File targetDirectory = new File(this.dataDirectory, key);
+				File[] subFiles = targetDirectory.listFiles();
+
+				if (subFiles == null)
+				{
+					result = 1;
+				}
+				else
+				{
+					result = subFiles.length;
+				}
+			}
+		}
+
+		//
+		return result;
+	}
+
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#countOfElements(java.lang.String, java.lang.String)
+	 */
+	@Override
+	public long countOfElements(final String key, final String subkey) throws UnopenedDatabaseException
+	{
+		long result;
+
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else
+		{
+			if ((key == null) || (subkey == null))
+			{
+				throw new IllegalArgumentException("Null key detected [key=" + key + "][subkey=" + subkey + "].");
+			}
+			else
+			{
+				File targetDirectory = new File(this.dataDirectory, key);
+				File targetFile = new File(targetDirectory, subkey);
+				if (targetFile.exists())
+				{
+					result = 1;
+				}
+				else
+				{
+					result = 0;
+				}
+			}
+		}
+		//
+		return result;
+	}
+
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#create()
 	 */
 	@Override
 	public void create() throws SikevaDBException
 	{
-		if (this.status == Status.OPENED)
+		if (this.status == Status.CLOSED)
 		{
-			throw new SikevaDBException("Invalid state.");
-		}
-		else if (this.fileTreeDirectory == null)
-		{
-			throw new SikevaDBException("Invalid root directory.");
-		}
-		else if (this.fileTreeDirectory.exists())
-		{
-			throw new SikevaDBException("Root directory already is existing.");
+			throw new UnopenedDatabaseException();
 		}
 		else
 		{
-			this.fileTreeDirectory.mkdir();
-			this.dataDirectory.mkdir();
-			this.configDirectory.mkdir();
+			if (this.status == Status.OPENED)
+			{
+				throw new SikevaDBException("Invalid state.");
+			}
+			else if (this.fileTreeDirectory == null)
+			{
+				throw new SikevaDBException("Invalid root directory.");
+			}
+			else if (this.fileTreeDirectory.exists())
+			{
+				throw new SikevaDBException("Root directory already is existing.");
+			}
+			else
+			{
+				this.fileTreeDirectory.mkdir();
+				this.dataDirectory.mkdir();
+				this.configDirectory.mkdir();
+			}
 		}
 	}
 
 	/**
-	 * 
-	 * @return
+	 * Gets the config directory.
+	 *
+	 * @return the config directory
 	 */
 	public File getConfigDirectory()
 	{
-		return this.configDirectory;
+		File result;
+
+		result = this.configDirectory;
+
+		return result;
 	}
 
 	/**
-	 * 
-	 * @return
+	 * Gets the data directory.
+	 *
+	 * @return the data directory
 	 */
 	public File getDataDirectory()
 	{
-		return this.dataDirectory;
+		File result;
+
+		result = this.dataDirectory;
+
+		//
+		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getElement(java.lang.String)
 	 */
 	@Override
 	public Element getElement(final String key) throws SikevaDBException
 	{
 		Element result;
 
-		if (key == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (key == null)
 		{
 			throw new IllegalArgumentException("Null key detected.");
 		}
@@ -277,17 +331,19 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getElement(java.lang.String, java.lang.String)
 	 */
 	@Override
 	public Element getElement(final String key, final String subkey) throws SikevaDBException
 	{
 		Element result;
 
-		//
-		if ((key == null) || (subkey == null))
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if ((key == null) || (subkey == null))
 		{
 			throw new IllegalArgumentException("Null key detected [key=" + key + "][subkey=" + subkey + "].");
 		}
@@ -309,34 +365,80 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getElements()
 	 */
 	@Override
 	public Elements getElements() throws SikevaDBException
 	{
 		Elements result;
 
-		result = new Elements((int) countOfElements());
-
-		File[] topFiles = this.dataDirectory.listFiles();
-		for (File file : topFiles)
+		if (this.status == Status.CLOSED)
 		{
-			if (file.isFile())
-			{
-				Element element = getElement(file.getName());
+			throw new UnopenedDatabaseException();
+		}
+		else
+		{
+			result = new Elements((int) countOfElements());
 
-				result.add(element);
-			}
-			else if (file.isDirectory())
+			File[] topFiles = this.dataDirectory.listFiles();
+			for (File file : topFiles)
 			{
-				File[] subFiles = file.listFiles();
-
-				for (File subFile : subFiles)
+				if (file.isFile())
 				{
-					if (subFile.isFile())
+					Element element = getElement(file.getName());
+
+					result.add(element);
+				}
+				else if (file.isDirectory())
+				{
+					File[] subFiles = file.listFiles();
+
+					for (File subFile : subFiles)
 					{
-						Element element = getElement(file.getName(), subFile.getName());
+						if (subFile.isFile())
+						{
+							Element element = getElement(file.getName(), subFile.getName());
+
+							result.add(element);
+						}
+					}
+				}
+			}
+		}
+		//
+		return result;
+	}
+
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getElements(java.lang.String)
+	 */
+	@Override
+	public Elements getElements(final String key) throws SikevaDBException
+	{
+		Elements result;
+
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else
+		{
+			if (key == null)
+			{
+				throw new IllegalArgumentException("Null key detected.");
+			}
+			else
+			{
+				result = new Elements((int) countOfElements(key));
+
+				File targetDirectory = new File(this.dataDirectory, key);
+				if (targetDirectory.exists())
+				{
+					File[] files = targetDirectory.listFiles();
+					for (File subfile : files)
+					{
+						Element element = getElement(key, subfile.getName());
 
 						result.add(element);
 					}
@@ -349,31 +451,46 @@ public class FileTreeSikevaDB implements SikevaDB
 	}
 
 	/**
-	 * {@inheritDoc}
-	 * 
+	 * Gets the file tree directory.
+	 *
+	 * @return the file tree directory
+	 */
+	public File getFileTreeDirectory()
+	{
+		File result;
+
+		result = this.fileTreeDirectory;
+
+		//
+		return result;
+	}
+
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getKeys()
 	 */
 	@Override
-	public Elements getElements(final String key) throws SikevaDBException
+	public StringList getKeys() throws SikevaDBException
 	{
-		Elements result;
+		StringList result;
 
-		if (key == null)
+		if (this.status == Status.CLOSED)
 		{
-			throw new IllegalArgumentException("Null key detected.");
+			throw new UnopenedDatabaseException();
 		}
 		else
 		{
-			result = new Elements((int) countOfElements(key));
+			result = new StringList((int) countOfElements());
 
-			File targetDirectory = new File(this.dataDirectory, key);
-			if (targetDirectory.exists())
+			File[] topFiles = this.dataDirectory.listFiles();
+			for (File file : topFiles)
 			{
-				File[] files = targetDirectory.listFiles();
-				for (File subfile : files)
+				if (file.isFile())
 				{
-					Element element = getElement(key, subfile.getName());
-
-					result.add(element);
+					result.add(file.getName());
+				}
+				else if (file.isDirectory())
+				{
+					result.add(file.getName());
 				}
 			}
 		}
@@ -383,73 +500,48 @@ public class FileTreeSikevaDB implements SikevaDB
 	}
 
 	/**
-	 * 
-	 * @return
+	 * Gets the login.
+	 *
+	 * @return the login
 	 */
-	public File getFileTreeDirectory()
+	public String getLogin()
 	{
-		return this.fileTreeDirectory;
-	}
+		String result;
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
-	 */
-	@Override
-	public StringList getKeys() throws SikevaDBException
-	{
-		StringList result;
-
-		//
-		result = new StringList((int) countOfElements());
-
-		File[] topFiles = this.dataDirectory.listFiles();
-		for (File file : topFiles)
-		{
-			if (file.isFile())
-			{
-				result.add(file.getName());
-			}
-			else if (file.isDirectory())
-			{
-				result.add(file.getName());
-			}
-		}
+		result = this.login;
 
 		//
 		return result;
 	}
 
 	/**
-	 * 
-	 * @return
-	 */
-	public String getLogin()
-	{
-		return this.login;
-	}
-
-	/**
-	 * 
-	 * @return
+	 * Gets the password.
+	 *
+	 * @return the password
 	 */
 	public String getPassword()
 	{
-		return this.password;
+		String result;
+
+		result = this.password;
+
+		//
+		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getSubkeys(java.lang.String)
 	 */
 	@Override
 	public StringList getSubkeys(final String key) throws SikevaDBException
 	{
 		StringList result;
 
-		if (key == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (key == null)
 		{
 			throw new IllegalArgumentException("Null key detected.");
 		}
@@ -473,17 +565,19 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getValue(java.lang.String)
 	 */
 	@Override
 	public String getValue(final String key) throws SikevaDBException
 	{
 		String result;
 
-		if (key == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (key == null)
 		{
 			throw new IllegalArgumentException("Null key detected.");
 		}
@@ -506,17 +600,19 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getValue(java.lang.String, java.lang.String)
 	 */
 	@Override
 	public String getValue(final String key, final String subkey) throws SikevaDBException
 	{
 		String result;
 
-		if ((key == null) || (subkey == null))
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if ((key == null) || (subkey == null))
 		{
 			throw new IllegalArgumentException("Null key detected [key=" + key + "][subkey=" + subkey + "].");
 		}
@@ -540,17 +636,19 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#getValues(java.lang.String)
 	 */
 	@Override
 	public StringList getValues(final String key) throws SikevaDBException
 	{
 		StringList result;
 
-		if (key == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (key == null)
 		{
 			throw new IllegalArgumentException("Null key detected.");
 		}
@@ -582,9 +680,8 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * 
-	 * @return
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#isClosed()
 	 */
 	@Override
 	public boolean isClosed()
@@ -597,8 +694,8 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#isCreated()
 	 */
 	@Override
 	public boolean isCreated() throws SikevaDBException
@@ -618,9 +715,8 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * 
-	 * @return
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#isOpened()
 	 */
 	@Override
 	public boolean isOpened()
@@ -640,40 +736,45 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#memorySize()
 	 */
 	@Override
 	public long memorySize() throws SikevaDBException
 	{
 		long result;
 
-		//
-		result = 0;
-
-		//
-		File[] topFiles = this.dataDirectory.listFiles();
-		for (File file : topFiles)
+		if (this.status == Status.CLOSED)
 		{
-			if (file.isFile())
-			{
-				Element element = FileTreeSikevaDBTools.loadElement(file);
+			throw new UnopenedDatabaseException();
+		}
+		else
+		{
+			//
+			result = 0;
 
-				result += element.getSize();
-			}
-			else if (file.isDirectory())
+			//
+			File[] topFiles = this.dataDirectory.listFiles();
+			for (File file : topFiles)
 			{
-				File[] subFiles = file.listFiles();
-
-				for (File subFile : subFiles)
+				if (file.isFile())
 				{
-					if (subFile.isFile())
-					{
-						Element element = FileTreeSikevaDBTools.loadElement(subFile);
+					Element element = FileTreeSikevaDBTools.loadElement(file);
 
-						result += element.getSize();
+					result += element.getSize();
+				}
+				else if (file.isDirectory())
+				{
+					File[] subFiles = file.listFiles();
+
+					for (File subFile : subFiles)
+					{
+						if (subFile.isFile())
+						{
+							Element element = FileTreeSikevaDBTools.loadElement(subFile);
+
+							result += element.getSize();
+						}
 					}
 				}
 			}
@@ -683,17 +784,19 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#memorySize(java.lang.String)
 	 */
 	@Override
 	public long memorySize(final String key) throws SikevaDBException
 	{
 		long result;
 
-		if (key == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (key == null)
 		{
 			throw new IllegalArgumentException("Null key detected.");
 		}
@@ -726,17 +829,19 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#memorySize(java.lang.String, java.lang.String)
 	 */
 	@Override
 	public long memorySize(final String key, final String subkey) throws SikevaDBException
 	{
 		long result;
 
-		if ((key == null) || (subkey == null))
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if ((key == null) || (subkey == null))
 		{
 			throw new IllegalArgumentException("Null key detected [key=" + key + "][subkey=" + subkey + "].");
 		}
@@ -761,8 +866,8 @@ public class FileTreeSikevaDB implements SikevaDB
 		return result;
 	}
 
-	/**
-	 * {@inheritDoc}
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#open()
 	 */
 	@Override
 	public void open() throws SikevaDBException
@@ -774,15 +879,17 @@ public class FileTreeSikevaDB implements SikevaDB
 		this.status = Status.OPENED;
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#put(fr.devinsy.sikevadb.core.Element)
 	 */
 	@Override
 	public void put(final Element element) throws SikevaDBException
 	{
-		if (element == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (element == null)
 		{
 			throw new IllegalArgumentException("element is null.");
 		}
@@ -819,15 +926,17 @@ public class FileTreeSikevaDB implements SikevaDB
 		}
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#put(java.lang.String, java.lang.String)
 	 */
 	@Override
 	public void put(final String key, final String value) throws SikevaDBException
 	{
-		if (key == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (key == null)
 		{
 			throw new IllegalArgumentException("Null key detected.");
 		}
@@ -854,15 +963,17 @@ public class FileTreeSikevaDB implements SikevaDB
 		}
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#put(java.lang.String, java.lang.String, java.lang.String)
 	 */
 	@Override
 	public void put(final String key, final String subkey, final String value) throws SikevaDBException
 	{
-		if ((key == null) || (subkey == null))
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if ((key == null) || (subkey == null))
 		{
 			throw new IllegalArgumentException("Null key detected [key=" + key + "][subkey=" + subkey + "].");
 		}
@@ -890,15 +1001,17 @@ public class FileTreeSikevaDB implements SikevaDB
 		}
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#remove(java.lang.String)
 	 */
 	@Override
 	public void remove(final String key) throws SikevaDBException
 	{
-		if (key == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (key == null)
 		{
 			throw new IllegalArgumentException("Null key detected.");
 		}
@@ -921,15 +1034,17 @@ public class FileTreeSikevaDB implements SikevaDB
 		}
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#remove(java.lang.String, java.lang.String)
 	 */
 	@Override
 	public void remove(final String key, final String subkey) throws SikevaDBException
 	{
-		if ((key == null) || (subkey == null))
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if ((key == null) || (subkey == null))
 		{
 			throw new IllegalArgumentException("Null key detected [key=" + key + "][subkey=" + subkey + "].");
 		}
@@ -953,15 +1068,17 @@ public class FileTreeSikevaDB implements SikevaDB
 		}
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#removeMany(java.lang.String, java.lang.String[])
 	 */
 	@Override
 	public void removeMany(final String key, final String... subkeys) throws SikevaDBException
 	{
-		if (key == null)
+		if (this.status == Status.CLOSED)
+		{
+			throw new UnopenedDatabaseException();
+		}
+		else if (key == null)
 		{
 			throw new IllegalArgumentException("Null key detected.");
 		}
@@ -977,156 +1094,181 @@ public class FileTreeSikevaDB implements SikevaDB
 		}
 	}
 
-	/**
-	 * {@inheritDoc}
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#renameKey(java.lang.String, java.lang.String)
 	 */
 	@Override
-	public void renameKey(final String oldKey, final String newKey)
+	public void renameKey(final String oldKey, final String newKey) throws UnopenedDatabaseException
 	{
-		this.logger.debug("renameKey starting... [{}][{}]", oldKey, newKey);
-
-		if (oldKey == null)
+		if (this.status == Status.CLOSED)
 		{
-			throw new IllegalArgumentException("OldKey is null.");
-		}
-		else if (newKey == null)
-		{
-			throw new IllegalArgumentException("OldKey is null.");
+			throw new UnopenedDatabaseException();
 		}
 		else
 		{
-			File oldFile = new File(this.dataDirectory, oldKey);
-			File newFile = new File(this.dataDirectory, newKey);
+			this.logger.debug("renameKey starting... [{}][{}]", oldKey, newKey);
 
-			if (oldFile.isFile())
+			if (oldKey == null)
 			{
-				if (newFile.isFile())
+				throw new IllegalArgumentException("OldKey is null.");
+			}
+			else if (newKey == null)
+			{
+				throw new IllegalArgumentException("OldKey is null.");
+			}
+			else
+			{
+				File oldFile = new File(this.dataDirectory, oldKey);
+				File newFile = new File(this.dataDirectory, newKey);
+
+				if (oldFile.isFile())
 				{
-					throw new IllegalArgumentException("Invalid newKey [" + newKey + "].");
+					if (newFile.isFile())
+					{
+						throw new IllegalArgumentException("Invalid newKey [" + newKey + "].");
+					}
+					else
+					{
+						oldFile.renameTo(newFile);
+					}
 				}
 				else
 				{
 					oldFile.renameTo(newFile);
 				}
 			}
-			else
-			{
-				oldFile.renameTo(newFile);
-			}
-		}
 
-		this.logger.debug("renameKey done.");
+			this.logger.debug("renameKey done.");
+		}
 	}
 
-	/**
-	 * {@inheritDoc}
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#renameSubKey(java.lang.String, java.lang.String, java.lang.String)
 	 */
 	@Override
 	public void renameSubKey(final String key, final String oldSubkey, final String newSubkey) throws SikevaDBException
 	{
-		this.logger.debug("renameSybKey starting... [{}][{}][{}]", oldSubkey, newSubkey);
-
-		if (key == null)
+		if (this.status == Status.CLOSED)
 		{
-			throw new IllegalArgumentException("Top key is null.");
-		}
-		if (oldSubkey == null)
-		{
-			throw new IllegalArgumentException("OldKey is null.");
-		}
-		else if (newSubkey == null)
-		{
-			throw new IllegalArgumentException("OldKey is null.");
+			throw new UnopenedDatabaseException();
 		}
 		else
 		{
-			File targetDirectory = new File(this.dataDirectory, key);
-			File oldFile = new File(targetDirectory, oldSubkey);
-			File newFile = new File(targetDirectory, newSubkey);
 
-			if (oldFile.isFile())
+			this.logger.debug("renameSybKey starting... [{}][{}][{}]", oldSubkey, newSubkey);
+
+			if (key == null)
 			{
-				if (newFile.isFile())
-				{
-					throw new IllegalArgumentException("Invalid newKey [" + newSubkey + "].");
-				}
-				else
-				{
-					oldFile.renameTo(newFile);
-				}
+				throw new IllegalArgumentException("Top key is null.");
+			}
+			if (oldSubkey == null)
+			{
+				throw new IllegalArgumentException("OldKey is null.");
+			}
+			else if (newSubkey == null)
+			{
+				throw new IllegalArgumentException("OldKey is null.");
 			}
 			else
 			{
-				throw new IllegalArgumentException("Invalid oldKey [" + oldSubkey + "].");
-			}
-		}
+				File targetDirectory = new File(this.dataDirectory, key);
+				File oldFile = new File(targetDirectory, oldSubkey);
+				File newFile = new File(targetDirectory, newSubkey);
 
-		this.logger.debug("renameSubKey done.");
+				if (oldFile.isFile())
+				{
+					if (newFile.isFile())
+					{
+						throw new IllegalArgumentException("Invalid newKey [" + newSubkey + "].");
+					}
+					else
+					{
+						oldFile.renameTo(newFile);
+					}
+				}
+				else
+				{
+					throw new IllegalArgumentException("Invalid oldKey [" + oldSubkey + "].");
+				}
+			}
+
+			this.logger.debug("renameSubKey done.");
+		}
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#replaceInValue(java.lang.String, java.lang.String[])
 	 */
 	@Override
 	public void replaceInValue(final String key, final String... tokens) throws SikevaDBException
 	{
-		this.logger.info("replaceInValue starting... [{}]", key);
-
-		//
-		String value = getValue(key);
-
-		//
-		for (int tokenIndex = 0; tokenIndex < tokens.length; tokenIndex += 2)
+		if (this.status == Status.CLOSED)
 		{
-			value = value.replaceAll(tokens[tokenIndex], tokens[tokenIndex + 1]);
+			throw new UnopenedDatabaseException();
 		}
+		else
+		{
+			this.logger.info("replaceInValue starting... [{}]", key);
 
-		//
-		put(key, value);
+			//
+			String value = getValue(key);
 
-		this.logger.info("replaceInValue done.");
+			//
+			for (int tokenIndex = 0; tokenIndex < tokens.length; tokenIndex += 2)
+			{
+				value = value.replaceAll(tokens[tokenIndex], tokens[tokenIndex + 1]);
+			}
+
+			//
+			put(key, value);
+
+			this.logger.info("replaceInValue done.");
+		}
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @throws SikevaDBException
+	/* (non-Javadoc)
+	 * @see fr.devinsy.sikevadb.core.SikevaDB#replaceInValues(java.lang.String, java.lang.String[])
 	 */
 	@Override
 	public void replaceInValues(final String key, final String... tokens) throws SikevaDBException
 	{
-		this.logger.info("replaceInValues starting... [{}]", key);
-
-		//
-		Elements elements = getElements(key);
-
-		long count = 0;
-		for (Element element : elements)
+		if (this.status == Status.CLOSED)
 		{
-			this.logger.info(element.getKey() + " (" + element.getSubkey() + ") " + count + "/" + elements.size());
-
-			if (element.getSubkey() != null)
-			{
-				//
-				count += 1;
-
-				//
-				String value = element.getValue();
-
-				//
-				for (int tokenIndex = 0; tokenIndex < tokens.length; tokenIndex += 2)
-				{
-					value = value.replaceAll(tokens[tokenIndex], tokens[tokenIndex + 1]);
-				}
-
-				//
-				put(element.getKey(), element.getSubkey(), value);
-			}
+			throw new UnopenedDatabaseException();
 		}
+		else
+		{
+			this.logger.info("replaceInValues starting... [{}]", key);
 
-		this.logger.info("replaceInValues done.");
+			//
+			Elements elements = getElements(key);
+
+			long count = 0;
+			for (Element element : elements)
+			{
+				this.logger.info(element.getKey() + " (" + element.getSubkey() + ") " + count + "/" + elements.size());
+
+				if (element.getSubkey() != null)
+				{
+					//
+					count += 1;
+
+					//
+					String value = element.getValue();
+
+					//
+					for (int tokenIndex = 0; tokenIndex < tokens.length; tokenIndex += 2)
+					{
+						value = value.replaceAll(tokens[tokenIndex], tokens[tokenIndex + 1]);
+					}
+
+					//
+					put(element.getKey(), element.getSubkey(), value);
+				}
+			}
+
+			this.logger.info("replaceInValues done.");
+		}
 	}
 
 	/**
diff --git a/test/fr/devinsy/sikevadb/filetree/TreeFileSikevaDBTest.java b/test/fr/devinsy/sikevadb/filetree/TreeFileSikevaDBTest.java
index e7f2bf2..c4aedf2 100644
--- a/test/fr/devinsy/sikevadb/filetree/TreeFileSikevaDBTest.java
+++ b/test/fr/devinsy/sikevadb/filetree/TreeFileSikevaDBTest.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2013-2017 Christian Pierre MOMON, DEVINSY
+ * Copyright (C) 2013-2018 Christian Pierre MOMON, DEVINSY
  * 
  * This file is part of SikevaDB, simple key value database.
  * 
@@ -34,6 +34,7 @@ import org.junit.Test;
 import fr.devinsy.sikevadb.core.Element;
 import fr.devinsy.sikevadb.core.Elements;
 import fr.devinsy.sikevadb.core.SikevaDBException;
+import fr.devinsy.sikevadb.core.UnopenedDatabaseException;
 import fr.devinsy.util.strings.StringList;
 
 /**
@@ -607,10 +608,11 @@ public class TreeFileSikevaDBTest
 	}
 
 	/**
+	 * @throws UnopenedDatabaseException
 	 * 
 	 */
 	@AfterClass
-	public static void afterClass()
+	public static void afterClass() throws UnopenedDatabaseException
 	{
 		if (database != null)
 		{