[IOTDB-6025] iotdb-api: fix bugs & smells reported by SonarCloud (#10318)

iotdb-api/external-api/src/main/java/org/apache/iotdb/external/api/IPropertiesLoader.java

@@ -16,17 +16,18 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.external.api;
 
 import java.util.Properties;
 
 /**
  * An interface to load properties from external properties file to override the default
- * configurations
+ * configurations.
  */
 public interface IPropertiesLoader {
   /**
-   * Load Properties from specific file
+   * Load Properties from specific file.
    *
    * @return a property list with values in file.
    */

iotdb-api/external-api/src/main/java/org/apache/iotdb/external/api/thrift/JudgableServerContext.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.external.api.thrift;
 
 import org.apache.thrift.server.ServerContext;
@@ -29,7 +30,11 @@ public interface JudgableServerContext extends ServerContext {
    */
   boolean whenConnect();
 
-  /** @return false if we do not allow this connection */
+  /**
+   * this method will be called when a client disconnects to the IoTDB server.
+   *
+   * @return false if we do not allow this connection
+   */
   boolean whenDisconnect();
 
   @Override
@@ -40,5 +45,5 @@ public interface JudgableServerContext extends ServerContext {
   @Override
   default boolean isWrapperFor(Class<?> iface) {
     return false;
-  };
+  }
 }

iotdb-api/external-api/src/main/java/org/apache/iotdb/external/api/thrift/ServerContextFactory.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.external.api.thrift;
 
 import org.apache.thrift.protocol.TProtocol;

iotdb-api/pipe-api/src/main/java/org/apache/iotdb/pipe/api/access/Row.java

@@ -24,7 +24,6 @@ import org.apache.iotdb.pipe.api.type.Binary;
 import org.apache.iotdb.pipe.api.type.Type;
 import org.apache.iotdb.tsfile.read.common.Path;
 
-import java.io.IOException;
 import java.util.List;
 
 public interface Row {
@@ -54,7 +53,7 @@ public interface Row {
    * @param columnIndex index of the specified column
    * @return the long value at the specified column in this row
    */
-  long getLong(int columnIndex) throws IOException;
+  long getLong(int columnIndex);
 
   /**
    * Returns the float value at the specified column in this row.
@@ -131,7 +130,7 @@ public interface Row {
   boolean isNull(int columnIndex);
 
   /**
-   * Returns the number of columns (excluding the timestamp column)
+   * Returns the number of columns (excluding the timestamp column).
    *
    * @return the number of columns (excluding the timestamp column)
    */
@@ -141,20 +140,20 @@ public interface Row {
    * Returns the actual column index of the given column name.
    *
    * @param columnName the column name in Path form
-   * @throws PipeParameterNotValidException if the given column name is not existed in the Row
    * @return the actual column index of the given column name
+   * @throws PipeParameterNotValidException if the given column name is not existed in the Row
    */
   int getColumnIndex(Path columnName) throws PipeParameterNotValidException;
 
   /**
-   * Returns the column data types in the Row
+   * Returns the column data types in the Row.
    *
    * @return the column data types in the Row
    */
   List<Type> getColumnTypes();
 
   /**
-   * Returns the device id of the Row
+   * Returns the device id of the Row.
    *
    * @return the device id of the Row
    */

iotdb-api/pipe-api/src/main/java/org/apache/iotdb/pipe/api/event/dml/insertion/TabletInsertionEvent.java

@@ -32,16 +32,16 @@ public interface TabletInsertionEvent extends Event {
   /**
    * The consumer processes the data row by row and collects the results by RowCollector.
    *
-   * @return Iterable<TabletInsertionEvent> a list of new TabletInsertionEvent contains the results
-   *     collected by the RowCollector
+   * @return {@code Iterable<TabletInsertionEvent>} a list of new TabletInsertionEvent contains the
+   *     results collected by the RowCollector
    */
   Iterable<TabletInsertionEvent> processRowByRow(BiConsumer<Row, RowCollector> consumer);
 
   /**
    * The consumer processes the Tablet directly and collects the results by RowCollector.
    *
-   * @return Iterable<TabletInsertionEvent> a list of new TabletInsertionEvent contains the results
-   *     collected by the RowCollector
+   * @return {@code Iterable<TabletInsertionEvent>} a list of new TabletInsertionEvent contains the
+   *     results collected by the RowCollector
    */
   Iterable<TabletInsertionEvent> processTablet(BiConsumer<Tablet, RowCollector> consumer);
 }

iotdb-api/pipe-api/src/main/java/org/apache/iotdb/pipe/api/event/dml/insertion/TsFileInsertionEvent.java

@@ -30,7 +30,7 @@ public interface TsFileInsertionEvent extends Event {
   /**
    * The method is used to convert the TsFileInsertionEvent into several TabletInsertionEvents.
    *
-   * @return the list of TsFileInsertionEvent
+   * @return {@code Iterable<TabletInsertionEvent>} the list of TabletInsertionEvent
    */
   Iterable<TabletInsertionEvent> toTabletInsertionEvents();
 }

iotdb-api/pipe-api/src/main/java/org/apache/iotdb/pipe/api/type/Binary.java

@@ -21,6 +21,7 @@ package org.apache.iotdb.pipe.api.type;
 
 import java.io.Serializable;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 
 /**
@@ -31,7 +32,7 @@ public class Binary implements Comparable<Binary>, Serializable {
 
   private static final long serialVersionUID = 1250049718612917815L;
   public static final String STRING_ENCODING = "UTF-8";
-  public static final Charset STRING_CHARSET = Charset.forName(STRING_ENCODING);
+  public static final Charset STRING_CHARSET = StandardCharsets.UTF_8;
 
   private final byte[] values;
 

iotdb-api/pipe-api/src/main/java/org/apache/iotdb/pipe/api/type/Type.java

@@ -20,31 +20,31 @@
 package org.apache.iotdb.pipe.api.type;
 
 public enum Type {
-  /** BOOLEAN */
+  /* BOOLEAN */
   BOOLEAN((byte) 0),
 
-  /** INT32 */
+  /* INT32 */
   INT32((byte) 1),
 
-  /** INT64 */
+  /* INT64 */
   INT64((byte) 2),
 
-  /** FLOAT */
+  /* FLOAT */
   FLOAT((byte) 3),
 
-  /** DOUBLE */
+  /* DOUBLE */
   DOUBLE((byte) 4),
 
-  /** TEXT */
+  /* TEXT */
   TEXT((byte) 5);
 
-  private final byte type;
+  private final byte dataType;
 
   Type(byte type) {
-    this.type = type;
+    this.dataType = type;
   }
 
   public byte getType() {
-    return type;
+    return dataType;
   }
 }

iotdb-api/subscription-api/src/main/java/org/apache/iotdb/subscription/api/SubscriptionConfiguration.java

@@ -33,7 +33,9 @@ public class SubscriptionConfiguration {
   private DisorderHandlingStrategy disorderHandlingStrategy;
   private TopicsStrategy topicStrategy;
 
-  private SubscriptionConfiguration() {}
+  private SubscriptionConfiguration() {
+    // allowed to be constructed by builder
+  }
 
   private void check() throws SubscriptionException {
     if (host == null) {

iotdb-api/subscription-api/src/main/java/org/apache/iotdb/subscription/api/consumer/Consumer.java

@@ -25,10 +25,18 @@ import java.util.List;
 
 public interface Consumer extends AutoCloseable {
 
-  /** Open the subscription. */
+  /**
+   * Open the subscription.
+   *
+   * @throws SubscriptionException if the subscription cannot be opened
+   */
   void openSubscription() throws SubscriptionException;
 
-  /** Close the subscription. */
+  /**
+   * Close the subscription.
+   *
+   * @throws SubscriptionException if the subscription cannot be closed
+   */
   void closeSubscription() throws SubscriptionException;
 
   /**

iotdb-api/subscription-api/src/main/java/org/apache/iotdb/subscription/api/strategy/SubscriptionStrategy.java

@@ -24,6 +24,10 @@ import org.apache.iotdb.subscription.api.exception.SubscriptionStrategyNotValidE
 /** Subscription strategy interface. */
 public interface SubscriptionStrategy {
 
-  /** @throws SubscriptionStrategyNotValidException if invalid strategy is set */
+  /**
+   * Check if the strategy is valid.
+   *
+   * @throws SubscriptionStrategyNotValidException if invalid strategy is set
+   */
   void check() throws SubscriptionStrategyNotValidException;
 }

iotdb-api/subscription-api/src/main/java/org/apache/iotdb/subscription/api/strategy/disorder/IntolerableStrategy.java

@@ -28,5 +28,7 @@ public class IntolerableStrategy extends DisorderHandlingStrategy {
   }
 
   @Override
-  public void check() throws SubscriptionStrategyNotValidException {}
+  public void check() throws SubscriptionStrategyNotValidException {
+    // do nothing
+  }
 }

iotdb-api/trigger-api/src/main/java/org/apache/iotdb/trigger/api/Trigger.java

@@ -67,6 +67,8 @@ public interface Trigger {
   }
 
   /**
+   * This method will be called when a trigger is fired.
+   *
    * @param tablet see {@link Tablet} for detailed information of data structure. Data that is
    *     inserted will be constructed as a Tablet and you can define process logic with {@link
    *     Tablet}.

iotdb-api/trigger-api/src/main/java/org/apache/iotdb/trigger/api/enums/FailureStrategy.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.trigger.api.enums;
 
 import org.apache.iotdb.trigger.api.Trigger;

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/UDF.java

@@ -33,8 +33,12 @@ public interface UDF {
    * @throws Exception if any parameter is not valid
    */
   @SuppressWarnings("squid:S112")
-  default void validate(UDFParameterValidator validator) throws Exception {}
+  default void validate(UDFParameterValidator validator) throws Exception {
+    // do nothing
+  }
 
   /** This method is mainly used to release the resources used in the UDF. */
-  default void beforeDestroy() {}
+  default void beforeDestroy() {
+    // do nothing
+  }
 }

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/UDTF.java

@@ -46,7 +46,7 @@ import org.apache.iotdb.udf.api.customizer.strategy.SlidingTimeWindowAccessStrat
  *       PointCollector)}
  * </ul>
  *
- * In the life cycle of a UDTF instance, the calling sequence of each method is as follows:
+ * <p>In the life cycle of a UDTF instance, the calling sequence of each method is as follows:
  *
  * <p>1. {@link UDTF#validate(UDFParameterValidator)} 2. {@link UDTF#beforeStart(UDFParameters,
  * UDTFConfigurations)} 3. {@link UDTF#transform(RowWindow, PointCollector)} or {@link
@@ -91,7 +91,9 @@ public interface UDTF extends UDF {
    * @see RowByRowAccessStrategy
    */
   @SuppressWarnings("squid:S112")
-  default void transform(Row row, PointCollector collector) throws Exception {}
+  default void transform(Row row, PointCollector collector) throws Exception {
+    // do nothing
+  }
 
   /**
    * When the user specifies {@link SlidingSizeWindowAccessStrategy} or {@link
@@ -106,7 +108,9 @@ public interface UDTF extends UDF {
    * @see SlidingTimeWindowAccessStrategy
    */
   @SuppressWarnings("squid:S112")
-  default void transform(RowWindow rowWindow, PointCollector collector) throws Exception {}
+  default void transform(RowWindow rowWindow, PointCollector collector) throws Exception {
+    // do nothing
+  }
 
   /**
    * When the user specifies {@link MappableRowByRowAccessStrategy} to access the original data in
@@ -115,6 +119,7 @@ public interface UDTF extends UDF {
    *
    * @param row original input data row (aligned by time)
    * @throws Exception the user can throw errors if necessary
+   * @throws UnsupportedOperationException if the user does not override this method
    * @see MappableRowByRowAccessStrategy
    */
   default Object transform(Row row) throws Exception {
@@ -122,13 +127,15 @@ public interface UDTF extends UDF {
   }
 
   /**
-   * This method will be called once after all {@link UDTF#transform(Row, PointCollector) calls or
-   * {@link UDTF#transform(RowWindow, PointCollector) calls have been executed. In a single UDF
+   * This method will be called once after all {@link UDTF#transform(Row, PointCollector)} calls or
+   * {@link UDTF#transform(RowWindow, PointCollector)} calls have been executed. In a single UDF
    * query, this method will and will only be called once.
    *
    * @param collector used to collect output data points
    * @throws Exception the user can throw errors if necessary
    */
   @SuppressWarnings("squid:S112")
-  default void terminate(PointCollector collector) throws Exception {}
+  default void terminate(PointCollector collector) throws Exception {
+    // do nothing
+  }
 }

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/access/Row.java

@@ -30,6 +30,7 @@ public interface Row {
    * Returns the timestamp of this row.
    *
    * @return timestamp
+   * @throws IOException if an I/O error occurs
    */
   long getTime() throws IOException;
 
@@ -40,6 +41,7 @@ public interface Row {
    *
    * @param columnIndex index of the specified column
    * @return the int value at the specified column in this row
+   * @throws IOException if an I/O error occurs
    */
   int getInt(int columnIndex) throws IOException;
 
@@ -50,6 +52,7 @@ public interface Row {
    *
    * @param columnIndex index of the specified column
    * @return the long value at the specified column in this row
+   * @throws IOException if an I/O error occurs
    */
   long getLong(int columnIndex) throws IOException;
 
@@ -60,6 +63,7 @@ public interface Row {
    *
    * @param columnIndex index of the specified column
    * @return the float value at the specified column in this row
+   * @throws IOException if an I/O error occurs
    */
   float getFloat(int columnIndex) throws IOException;
 
@@ -71,6 +75,7 @@ public interface Row {
    *
    * @param columnIndex index of the specified column
    * @return the double value at the specified column in this row
+   * @throws IOException if an I/O error occurs
    */
   double getDouble(int columnIndex) throws IOException;
 
@@ -82,6 +87,7 @@ public interface Row {
    *
    * @param columnIndex index of the specified column
    * @return the boolean value at the specified column in this row
+   * @throws IOException if an I/O error occurs
    */
   boolean getBoolean(int columnIndex) throws IOException;
 
@@ -92,6 +98,7 @@ public interface Row {
    *
    * @param columnIndex index of the specified column
    * @return the Binary value at the specified column in this row
+   * @throws IOException if an I/O error occurs
    */
   Binary getBinary(int columnIndex) throws IOException;
 
@@ -102,6 +109,7 @@ public interface Row {
    *
    * @param columnIndex index of the specified column
    * @return the String value at the specified column in this row
+   * @throws IOException if an I/O error occurs
    */
   String getString(int columnIndex) throws IOException;
 
@@ -122,7 +130,7 @@ public interface Row {
   boolean isNull(int columnIndex);
 
   /**
-   * Returns the number of columns
+   * Returns the number of columns.
    *
    * @return the number of columns
    */

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/config/UDTFConfigurations.java

@@ -34,16 +34,18 @@ import java.time.ZoneId;
 
 /**
  * Used in {@link UDTF#beforeStart(UDFParameters, UDTFConfigurations)}.
- * <p>
- * Supports calling methods in a chain.
- * <p>
- * Sample code:
+ *
+ * <p>Supports calling methods in a chain.
+ *
+ * <p>Sample code:
+ *
  * <pre>{@code
  * @Override
  * public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations) {
  *   configurations
  *       .setOutputDataType(TSDataType.INT64)
  *       .setAccessStrategy(new RowByRowAccessStrategy());
+ * }
  * }</pre>
  */
 public class UDTFConfigurations extends UDFConfigurations {

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/parameter/UDFParameterValidator.java

@@ -59,6 +59,8 @@ public class UDFParameterValidator {
    *
    * @param index index of the specified column
    * @param expectedDataType the expected data type
+   * @throws UDFException there are two exceptions that may be thrown:
+   *     UDFInputSeriesIndexNotValidException and UDFInputSeriesDataTypeNotValidException
    * @throws UDFInputSeriesIndexNotValidException if the index of the specified column is out of
    *     bound
    * @throws UDFInputSeriesDataTypeNotValidException if the data type of the input series at the
@@ -82,6 +84,8 @@ public class UDFParameterValidator {
    *
    * @param index index of the specified column
    * @param expectedDataTypes the expected data types
+   * @throws UDFException there are two exceptions that may be thrown:
+   *     UDFInputSeriesIndexNotValidException and UDFInputSeriesDataTypeNotValidException
    * @throws UDFInputSeriesIndexNotValidException if the index of the specified column is out of
    *     bound
    * @throws UDFInputSeriesDataTypeNotValidException if the data type of the input series at the

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/strategy/AccessStrategy.java

@@ -31,22 +31,46 @@ public interface AccessStrategy {
 
   enum AccessStrategyType {
 
-    /** @see MappableRowByRowAccessStrategy */
+    /**
+     * Represents the access strategy type for mappable row-by-row access.
+     *
+     * @see MappableRowByRowAccessStrategy
+     */
     MAPPABLE_ROW_BY_ROW,
 
-    /** @see RowByRowAccessStrategy */
+    /**
+     * Represents the access strategy type for row-by-row access.
+     *
+     * @see RowByRowAccessStrategy
+     */
     ROW_BY_ROW,
 
-    /** @see SlidingTimeWindowAccessStrategy */
+    /**
+     * Represents the access strategy type for sliding time window access.
+     *
+     * @see SlidingTimeWindowAccessStrategy
+     */
     SLIDING_TIME_WINDOW,
 
-    /** @see SlidingSizeWindowAccessStrategy */
+    /**
+     * Represents the access strategy type for sliding size window access.
+     *
+     * @see SlidingSizeWindowAccessStrategy
+     */
     SLIDING_SIZE_WINDOW,
 
-    /** @see SessionTimeWindowAccessStrategy */
+    /**
+     * Represents the access strategy type for session time window access.
+     *
+     * @see SessionTimeWindowAccessStrategy
+     */
     SESSION_TIME_WINDOW,
 
-    /** @see StateWindowAccessStrategy */
+    /**
+     * Represents the access strategy type for state window access.
+     *
+     * @see StateWindowAccessStrategy
+     */
     STATE_WINDOW
   }
 

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/strategy/MappableRowByRowAccessStrategy.java

@@ -26,21 +26,23 @@ import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
 
 /**
  * Used in {@link UDTF#beforeStart(UDFParameters, UDTFConfigurations)}.
- * <p>
- * When the access strategy of a UDTF is set to an instance of this class, the method {@link
- * UDTF#transform(Row)} of the UDTF will be called to transform the original data.
- * You need to override the method in your own UDTF class.
- * <p>
- * Each call of the method {@link UDTF#transform(Row)} processes only one row
- * (aligned by time) of the original data and can generate any number of data points.
- * <p>
- * Sample code:
+ *
+ * <p>When the access strategy of a UDTF is set to an instance of this class, the method {@link
+ * UDTF#transform(Row)} of the UDTF will be called to transform the original data. You need to
+ * override the method in your own UDTF class.
+ *
+ * <p>Each call of the method {@link UDTF#transform(Row)} processes only one row (aligned by time)
+ * of the original data and can generate any number of data points.
+ *
+ * <p>Sample code:
+ *
  * <pre>{@code
  * @Override
  * public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations) {
  *   configurations
  *       .setOutputDataType(TSDataType.INT64)
  *       .setAccessStrategy(new MappableRowByRowAccessStrategy());
+ * }
  * }</pre>
  *
  * @see UDTF

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/strategy/RowByRowAccessStrategy.java

@@ -27,21 +27,23 @@ import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
 
 /**
  * Used in {@link UDTF#beforeStart(UDFParameters, UDTFConfigurations)}.
- * <p>
- * When the access strategy of a UDTF is set to an instance of this class, the method {@link
+ *
+ * <p>When the access strategy of a UDTF is set to an instance of this class, the method {@link
  * UDTF#transform(Row, PointCollector)} of the UDTF will be called to transform the original data.
  * You need to override the method in your own UDTF class.
- * <p>
- * Each call of the method {@link UDTF#transform(Row, PointCollector)} processes only one row
+ *
+ * <p>Each call of the method {@link UDTF#transform(Row, PointCollector)} processes only one row
  * (aligned by time) of the original data and can generate any number of data points.
- * <p>
- * Sample code:
+ *
+ * <p>Sample code:
+ *
  * <pre>{@code
  * @Override
  * public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations) {
  *   configurations
  *       .setOutputDataType(TSDataType.INT64)
  *       .setAccessStrategy(new RowByRowAccessStrategy());
+ * }
  * }</pre>
  *
  * @see UDTF

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/strategy/SessionTimeWindowAccessStrategy.java

@@ -30,6 +30,8 @@ public class SessionTimeWindowAccessStrategy implements AccessStrategy {
   private ZoneId zoneId;
 
   /**
+   * Display window begin, display window end and sessionTimeGap will be set by the parameters.
+   *
    * @param displayWindowBegin displayWindowBegin < displayWindowEnd
    * @param displayWindowEnd displayWindowBegin < displayWindowEnd
    * @param sessionTimeGap 0 <= sessionTimeGap

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/strategy/SlidingSizeWindowAccessStrategy.java

@@ -27,23 +27,25 @@ import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
 
 /**
  * Used in {@link UDTF#beforeStart(UDFParameters, UDTFConfigurations)}.
- * <p>
- * When the access strategy of a UDTF is set to an instance of this class, the method {@link
+ *
+ * <p>When the access strategy of a UDTF is set to an instance of this class, the method {@link
  * UDTF#transform(RowWindow, PointCollector)} of the UDTF will be called to transform the original
  * data. You need to override the method in your own UDTF class.
- * <p>
- * Sliding size window is a kind of size-based window. Except for the last call, each call of the
+ *
+ * <p>Sliding size window is a kind of size-based window. Except for the last call, each call of the
  * method {@link UDTF#transform(RowWindow, PointCollector)} processes a window with {@code
  * windowSize} rows (aligned by time) of the original data and can generate any number of data
  * points.
- * <p>
- * Sample code:
+ *
+ * <p>Sample code:
+ *
  * <pre>{@code
  * @Override
  * public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations) {
  *   configurations
  *       .setOutputDataType(TSDataType.INT32)
  *       .setAccessStrategy(new SlidingSizeWindowAccessStrategy(10000)); // window size
+ * }
  * }</pre>
  *
  * @see UDTF
@@ -72,7 +74,7 @@ public class SlidingSizeWindowAccessStrategy implements AccessStrategy {
    *   <li>(7, 102, 'error')
    * </ul>
    *
-   * Set windowSize to 2 and set slidingStep to 3, windows will be generated as below: Window 0:
+   * <p>Set windowSize to 2 and set slidingStep to 3, windows will be generated as below: Window 0:
    * [(1, 100, null ), (2, 100, null)] Window 1: [(4, 100, 'error'), (5, 100, null)] Window 2: [(7,
    * 102, 'error')]
    *

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/strategy/SlidingTimeWindowAccessStrategy.java

@@ -29,29 +29,30 @@ import java.time.ZoneId;
 
 /**
  * Used in {@link UDTF#beforeStart(UDFParameters, UDTFConfigurations)}.
- * <p>
- * When the access strategy of a UDTF is set to an instance of this class, the method {@link
+ *
+ * <p>When the access strategy of a UDTF is set to an instance of this class, the method {@link
  * UDTF#transform(RowWindow, PointCollector)} of the UDTF will be called to transform the original
  * data. You need to override the method in your own UDTF class.
- * <p>
- * Sliding time window is a kind of time-based window. To partition the raw query data set into
+ *
+ * <p>Sliding time window is a kind of time-based window. To partition the raw query data set into
  * sliding time windows, you need to give the following 4 parameters:
- * <p>
- * <li> display window begin: determines the start time of the first window
- * <li> display window end: if the start time of current window + sliding step > display window
- * end, then current window is the last window that your UDTF can process
- * <li> time interval: determines the time range of a window
- * <li> sliding step: the start time of the next window = the start time of current window +
- * sliding step
- * <p>
- * Each call of the method {@link UDTF#transform(RowWindow, PointCollector)} processes one time
- * window and can generate any number of data points. Note that the transform method will still be
- * called when there is no data point in a window. Note that the time range of the last few windows
- * may be less than the specified time interval.
- * <p>
- * Sample code:
- * <p>Style 1:
- * <pre>{@code
+ * <li>display window begin: determines the start time of the first window
+ * <li>display window end: if the start time of current window + sliding step > display window end,
+ *     then current window is the last window that your UDTF can process
+ * <li>time interval: determines the time range of a window
+ * <li>sliding step: the start time of the next window = the start time of current window + sliding
+ *     step
+ *
+ *     <p>Each call of the method {@link UDTF#transform(RowWindow, PointCollector)} processes one
+ *     time window and can generate any number of data points. Note that the transform method will
+ *     still be called when there is no data point in a window. Note that the time range of the last
+ *     few windows may be less than the specified time interval.
+ *
+ *     <p>Sample code:
+ *
+ *     <p>Style 1:
+ *
+ *     <pre>{@code
  * @Override
  * public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations) {
  *   configurations.setAccessStrategy(new SlidingTimeWindowAccessStrategy(
@@ -59,9 +60,12 @@ import java.time.ZoneId;
  *       parameters.getLong(50),      // sliding step
  *       parameters.getLong(0),       // display window begin
  *       parameters.getLong(10000))); // display window end
+ * }
  * }</pre>
- * <p>Style 2 (deprecated since v0.14):
- * <pre>{@code
+ *
+ *     <p>Style 2 (deprecated since v0.14):
+ *
+ *     <pre>{@code
  * @Override
  * public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations) {
  *   configurations.setAccessStrategy(new SlidingTimeWindowAccessStrategy(
@@ -69,6 +73,7 @@ import java.time.ZoneId;
  *       parameters.getLong("7d"),                    // sliding step
  *       parameters.getLong("2020-01-01T00:00:00"),   // display window begin
  *       parameters.getLong("2020-06-01T00:00:00"))); // display window end
+ * }
  * }</pre>
  *
  * @see UDTF
@@ -95,6 +100,7 @@ public class SlidingTimeWindowAccessStrategy implements AccessStrategy {
    * @param displayWindowEndString display window end in string. format: 2011-12-03T10:15:30 or
    *     2011-12-03T10:15:30+01:00.
    * @throws UnsupportedOperationException deprecated since v0.14
+   * @deprecated use {@link #SlidingTimeWindowAccessStrategy(long, long, long, long)} instead.
    */
   @Deprecated
   public SlidingTimeWindowAccessStrategy(
@@ -117,6 +123,7 @@ public class SlidingTimeWindowAccessStrategy implements AccessStrategy {
    * @param slidingStepString sliding step in string. examples: 12d8m9ns, 1y1mo, etc. supported
    *     units: y, mo, w, d, h, m, s, ms, us, ns.
    * @throws UnsupportedOperationException deprecated since v0.14
+   * @deprecated use {@link #SlidingTimeWindowAccessStrategy(long, long)} instead.
    */
   @Deprecated
   public SlidingTimeWindowAccessStrategy(String timeIntervalString, String slidingStepString) {
@@ -139,6 +146,8 @@ public class SlidingTimeWindowAccessStrategy implements AccessStrategy {
   }
 
   /**
+   * Display window begin and display window end will be set by the parameters.
+   *
    * @param timeInterval 0 < timeInterval
    * @param slidingStep 0 < slidingStep
    * @param displayWindowBegin displayWindowBegin < displayWindowEnd

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/strategy/StateWindowAccessStrategy.java

@@ -30,6 +30,8 @@ public class StateWindowAccessStrategy implements AccessStrategy {
   private ZoneId zoneId;
 
   /**
+   * Display window begin, display window end and delta will be set by the parameters.
+   *
    * @param displayWindowBegin displayWindowBegin < displayWindowEnd
    * @param displayWindowEnd displayWindowBegin < displayWindowEnd
    * @param delta delta >= 0
@@ -41,6 +43,9 @@ public class StateWindowAccessStrategy implements AccessStrategy {
   }
 
   /**
+   * Display window begin and display window end will be set by the parameters. delta default equals
+   * 0.
+   *
    * @param displayWindowBegin displayWindowBegin < displayWindowEnd
    * @param displayWindowEnd displayWindowBegin < displayWindowEnd
    */

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/type/Binary.java

@@ -16,10 +16,12 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.udf.api.type;
 
 import java.io.Serializable;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 
 /**
@@ -30,7 +32,7 @@ public class Binary implements Comparable<Binary>, Serializable {
 
   private static final long serialVersionUID = 1250049718612917815L;
   public static final String STRING_ENCODING = "UTF-8";
-  public static final Charset STRING_CHARSET = Charset.forName(STRING_ENCODING);
+  public static final Charset STRING_CHARSET = StandardCharsets.UTF_8;
 
   private final byte[] values;
 

iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/type/Type.java

@@ -16,35 +16,36 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.udf.api.type;
 
 /** A substitution class for TsDataType in UDF APIs. */
 public enum Type {
-  /** BOOLEAN */
+  /* BOOLEAN */
   BOOLEAN((byte) 0),
 
-  /** INT32 */
+  /* INT32 */
   INT32((byte) 1),
 
-  /** INT64 */
+  /* INT64 */
   INT64((byte) 2),
 
-  /** FLOAT */
+  /* FLOAT */
   FLOAT((byte) 3),
 
-  /** DOUBLE */
+  /* DOUBLE */
   DOUBLE((byte) 4),
 
-  /** TEXT */
+  /* TEXT */
   TEXT((byte) 5);
 
-  private final byte type;
+  private final byte dataType;
 
   Type(byte type) {
-    this.type = type;
+    this.dataType = type;
   }
 
   public byte getType() {
-    return type;
+    return dataType;
   }
 }