--- a/src/main/java/org/monetdb/jdbc/MonetConnection.java
+++ b/src/main/java/org/monetdb/jdbc/MonetConnection.java
@@ -1695,7 +1695,7 @@ public class MonetConnection
 	}
 
 	/**
-	 * Returns the currently registerered {@link UploadHandler}, or null
+	 * @return the currently registerered {@link UploadHandler}, or null
 	 */
 	public UploadHandler getUploadHandler() {
 		return uploadHandler;
@@ -1711,7 +1711,7 @@ public class MonetConnection
 	}
 
 	/**
-	 * Returns the currently registerered {@link DownloadHandler} handler, or null
+	 * @return the currently registerered {@link DownloadHandler} handler, or null
 	 */
 	public DownloadHandler getDownloadHandler() {
 		return downloadHandler;
@@ -3304,6 +3304,7 @@ public class MonetConnection
 		 *                    0 means upload everything, 1 means skip the first line, etc.
 		 *                    Note: this is different from the OFFSET option of the COPY INTO,
 		 *                    where both 0 and 1 mean 'upload everything'
+		 * @throws IOException when I/O problem occurs
 		 */
 		void handleUpload(Upload handle, String name, boolean textMode, long linesToSkip) throws IOException;
 
@@ -3332,6 +3333,7 @@ public class MonetConnection
 		 * @param name Name of the file the server would like to write. Make sure
 		 *             to validate this before writing to the file system
 		 * @param textMode Whether this is text or binary data.
+		 * @throws IOException when I/O problem occurs
 		 */
 		void handleDownload(Download handle, String name, boolean textMode) throws IOException;
 	}
@@ -3362,7 +3364,9 @@ public class MonetConnection
 		 * This method can only be sent if no data has been sent to the server
 		 * yet. After data has been sent, you can still throw an
 		 * {@link IOException} but this will terminate the connection.
-		 * @param errorMessage error message to send
+		 *
+		 * @param errorMessage the error message to send
+		 * @throws IOException when error message is null
 		 */
 		public void sendError(final String errorMessage) throws IOException {
 			if (error != null) {
@@ -3374,6 +3378,8 @@ public class MonetConnection
 		/**
 		 * After every {@code chunkSize} bytes, the server gets the opportunity to
 		 * terminate the upload.
+		 *
+		 * @param chunkSize size of chunk
 		 */
 		public void setChunkSize(final int chunkSize) {
 			this.customChunkSize = chunkSize;
@@ -3383,6 +3389,9 @@ public class MonetConnection
 		 * Get a {@link PrintStream} to write data to.
 		 *
 		 * For text mode uploads, the data MUST be validly UTF-8 encoded.
+		 *
+		 * @return PrintStream a PrintStream
+		 * @throws IOException when error message is null or I/O problem occurs
 		 */
 		public PrintStream getStream() throws IOException {
 			if (error != null) {
@@ -3419,6 +3428,9 @@ public class MonetConnection
 		 * Read from the given input stream and write it to the server.
 		 *
 		 * For text mode uploads, the data MUST be validly UTF-8 encoded.
+		 *
+		 * @param inputStream stream to read from
+		 * @throws IOException when I/O problem occurs
 		 */
 		public void uploadFrom(final InputStream inputStream) throws IOException {
 			final OutputStream s = getStream();
@@ -3434,9 +3446,11 @@ public class MonetConnection
 
 		/**
 		 * Read data from the given buffered reader and send it to the server
-		 * @param reader reader to read from
+		 *
+		 * @param reader buffered reader to read from
 		 * @param linesToSkip start uploading at line {@code offset}. Value 0 and 1
 		 *        both mean upload the whole file, value 2 means skip the first line, etc.
+		 * @throws IOException when I/O problem occurs
 		 */
 		public void uploadFrom(final BufferedReader reader, final long linesToSkip) throws IOException {
 			for (int i = 0; i < linesToSkip; i++) {
@@ -3451,7 +3465,9 @@ public class MonetConnection
 
 		/**
 		 * Read data from the given buffered reader and send it to the server
+		 *
 		 * @param reader reader to read from
+		 * @throws IOException when ...
 		 */
 		public void uploadFrom(final Reader reader) throws IOException {
 			final OutputStream s = getStream();
@@ -3507,6 +3523,9 @@ public class MonetConnection
 		 *
 		 * Note: as of MonetDB version Jul2021 the server always terminates the connection
 		 * when this error is used.  This will probably change in the future.
+		 *
+		 * @param errorMessage the error message to send
+		 * @throws IOException when error message is null
 		 */
 		public void sendError(final String errorMessage) throws IOException {
 			if (error != null) {
@@ -3521,6 +3540,9 @@ public class MonetConnection
 		 * Textual data is UTF-8 encoded. If the download is in text mode, line endings
 		 * are converted according to {@link java.lang.System#lineSeparator()}.
 		 * This can be overridden with {@link Download#setLineSeparator(String)}.
+		 *
+		 * @return InputStream the stream to read from
+		 * @throws IOException when error message exist or I/O problem occurs
 		 */
 		public InputStream getStream() throws IOException {
 			if (error != null) {
@@ -3535,6 +3557,9 @@ public class MonetConnection
 
 		/**
 		 * Write the data from the server to the given {@link OutputStream}.
+		 *
+		 * @param stream the OutputStream to write to
+		 * @throws IOException when cannot read from InputStream or write to OutputStream
 		 */
 		public void downloadTo(final OutputStream stream) throws IOException {
 			final InputStream s = getStream();
@@ -3550,7 +3575,9 @@ public class MonetConnection
 
 		/**
 		 * Write the textual data from the server to the given {@link Writer}
-		 * @param writer
+		 *
+		 * @param writer to write to
+		 * @throws IOException when cannot read from InputStreamReader or write to Writer
 		 */
 		public void downloadTo(final Writer writer) throws IOException {
 			final InputStream s = getStream();
@@ -3566,7 +3593,7 @@ public class MonetConnection
 		}
 
 		/**
-		 * @return  true if data has been received or an error has been sent.
+		 * @return true if data has been received or an error has been sent.
 		 */
 		public boolean hasBeenUsed() {
 			return stream != null || error != null;
@@ -3595,6 +3622,7 @@ public class MonetConnection
 
 		/**
 		 * Set the line endings used in the stream returned by {@link Download#getStream()}
+		 *
 		 * @param sep separator to use
 		 * @throws IllegalArgumentException if sep is neither "\n" nor "\r\n"
 		 */

--- a/src/main/java/org/monetdb/jdbc/MonetDatabaseMetaData.java
+++ b/src/main/java/org/monetdb/jdbc/MonetDatabaseMetaData.java
@@ -96,7 +96,8 @@ public class MonetDatabaseMetaData
 	 * In an ascending order, if this method returns true, NULL values will appear at the end.
 	 * By contrast, the method nullsAreSortedAtEnd indicates whether NULL values are sorted at the end regardless of sort order.
 	 *
-	 * @return false because MonetDB shows NULL values at the beginning upon ORDER BY .. ASC
+	 * @return false because MonetDB shows NULL values at the beginning upon ORDER BY .. ASC, not at the end
+	 * @see #nullsAreSortedLow()
 	 */
 	@Override
 	public boolean nullsAreSortedHigh() {
@@ -110,8 +111,6 @@ public class MonetDatabaseMetaData
 	 * By contrast, the method nullsAreSortedAtStart indicates whether NULL values are sorted at the beginning regardless of sort order.
 	 *
 	 * @return true because MonetDB shows NULL values at the beginning upon ORDER BY .. ASC
-	 *
-	 * @return negative of nullsAreSortedHigh()
 	 * @see #nullsAreSortedHigh()
 	 */
 	@Override
@@ -362,7 +361,7 @@ public class MonetDatabaseMetaData
 
 	/**
 	 * Internal utility method getConcatenatedStringFromQuery(String query)
-	 * args: query: SQL SELECT query. Only the output of the first column is concatenated.
+	 * @param query the SQL SELECT query. Only the output of the first column is fetched and concatenated.
 	 * @return a String of query result values concatenated into one string, and values separated by comma's
 	 */
 	private String getConcatenatedStringFromQuery(final String query) {

--- a/src/main/java/org/monetdb/jdbc/MonetDriver.java.in
+++ b/src/main/java/org/monetdb/jdbc/MonetDriver.java.in
@@ -32,7 +32,7 @@ import java.util.Properties;
  * to be set in order to use this driver.
  *
  * This Driver supports MonetDB database URLs. MonetDB URLs are defined as:
- * <tt>jdbc:monetdb://&lt;host&gt;[:&lt;port&gt;]/&lt;database&gt;</tt>
+ * <code>jdbc:monetdb://&lt;host&gt;[:&lt;port&gt;]/&lt;database&gt;</code>
  * where [:&lt;port&gt;] denotes that a port is optional. If not
  * given the default (@JDBC_DEF_PORT@) will be used.
  *</pre>

--- a/src/main/java/org/monetdb/mcl/io/LineType.java
+++ b/src/main/java/org/monetdb/mcl/io/LineType.java
@@ -54,6 +54,9 @@ public enum LineType {
 
 	/**
 	 * Look at a mapi message and decide the LineType
+	 *
+	 * @param line the line containing the coded LineType
+	 * @return LineType the type of line
 	 */
 	public static final LineType classify(String line) {
 		if (line != null) {
@@ -68,6 +71,9 @@ public enum LineType {
 
 	/**
 	 * Look at a mapi message and decide the LineType
+	 *
+	 * @param line the line containing the coded LineType
+	 * @return LineType the type of line
 	 */
 	public static final LineType classify(byte[] line) {
 		if (line != null) {

--- a/src/main/java/org/monetdb/mcl/net/MapiSocket.java
+++ b/src/main/java/org/monetdb/mcl/net/MapiSocket.java
@@ -728,6 +728,9 @@ public class MapiSocket {	/* cannot (yet
 
 	/**
 	 * For internal use
+	 *
+	 * @param b to enable/disable insert 'fake' newline and prompt
+	 * @return previous setting
 	 */
 	public boolean setInsertFakePrompts(boolean b) {
 		return fromMonet.setInsertFakePrompts(b);
@@ -1179,7 +1182,9 @@ public class MapiSocket {	/* cannot (yet
 	 * Return an UploadStream for use with for example COPY FROM filename ON CLIENT.
 	 *
 	 * Building block for {@link org.monetdb.jdbc.MonetConnection.UploadHandler}.
+	 *
 	 * @param chunkSize chunk size for the upload stream
+	 * @return UploadStream new upload stream with the given chunk size
 	 */
 	public UploadStream uploadStream(int chunkSize) {
 		return new UploadStream(chunkSize);
@@ -1189,6 +1194,8 @@ public class MapiSocket {	/* cannot (yet
 	 * Return an UploadStream for use with for example COPY FROM filename ON CLIENT.
 	 *
 	 * Building block for {@link org.monetdb.jdbc.MonetConnection.UploadHandler}.
+	 *
+	 * @return UploadStream new upload stream
 	 */
 	public UploadStream uploadStream() {
 		return new UploadStream();
@@ -1198,7 +1205,9 @@ public class MapiSocket {	/* cannot (yet
 	 * Return a DownloadStream for use with for example COPY INTO filename ON CLIENT
 	 *
 	 * Building block for {@link org.monetdb.jdbc.MonetConnection.DownloadHandler}.
+	 *
 	 * @param prependCr convert \n to \r\n
+	 * @return DownloadStream new download stream
 	 */
 	public DownloadStream downloadStream(boolean prependCr) {
 		return new DownloadStream(fromMonet.getRaw(), toMonet, prependCr);
@@ -1255,6 +1264,8 @@ public class MapiSocket {	/* cannot (yet
 		}
 
 		/** Set a callback to be invoked if the server cancels the upload
+		 *
+		 * @param cancellationCallback callback to call
 		 */
 		public void setCancellationCallback(final Runnable cancellationCallback) {
 			this.cancellationCallback = cancellationCallback;