iotdb-connector: fix bugs & smells reported by SonarCloud (#10310)

iotdb-connector/flink-iotdb-connector/src/main/java/org/apache/iotdb/flink/DefaultIoTSerializationSchema.java

@@ -80,6 +80,8 @@ public class DefaultIoTSerializationSchema implements IoTSerializationSchema<Map
         case BOOLEAN:
           values.add(Boolean.parseBoolean(valuesStr[i]));
           break;
+        default:
+          continue;
       }
     }
 

iotdb-connector/flink-iotdb-connector/src/main/java/org/apache/iotdb/flink/IoTDBSink.java

@@ -57,7 +57,7 @@ public class IoTDBSink<IN> extends RichSinkFunction<IN> {
 
   private int batchSize = 0;
   private int flushIntervalMs = 3000;
-  private List<Event> batchList;
+  private transient List<Event> batchList;
   private int sessionPoolSize = 2;
 
   public IoTDBSink(IoTDBSinkOptions options, IoTSerializationSchema<IN> schema) {
@@ -188,7 +188,7 @@ public class IoTDBSink<IN> extends RichSinkFunction<IN> {
   private void flush() throws Exception {
     if (batchSize > 0) {
       synchronized (batchList) {
-        if (batchList.size() > 0) {
+        if (!batchList.isEmpty()) {
           List<String> deviceIds = new ArrayList<>();
           List<Long> timestamps = new ArrayList<>();
           List<List<String>> measurementsList = new ArrayList<>();

iotdb-connector/flink-iotdb-connector/src/test/java/org/apache/iotdb/flink/IoTDBSinkBatchTimerTest.java

@@ -28,6 +28,8 @@ import org.junit.Test;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
 
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.mock;
@@ -62,14 +64,13 @@ public class IoTDBSinkBatchTimerTest {
     tuple.put("types", "DOUBLE");
     tuple.put("values", "36.5");
     ioTDBSink.invoke(tuple, null);
-
-    Thread.sleep(2500);
+    new CountDownLatch(1).await(2500, TimeUnit.MILLISECONDS);
 
     verify(pool)
         .insertRecords(
             any(List.class), any(List.class), any(List.class), any(List.class), any(List.class));
 
-    Thread.sleep(1000);
+    new CountDownLatch(1).await(1000, TimeUnit.MILLISECONDS);
 
     verifyZeroInteractions(pool);
   }

iotdb-connector/flink-tsfile-connector/src/main/java/org/apache/iotdb/flink/tsfile/RowTSRecordConverter.java

@@ -150,7 +150,7 @@ public class RowTSRecordConverter implements TSRecordConverter<Row> {
       }
     }
     for (TSRecord tsRecord : reuse) {
-      if (tsRecord.dataPointList.size() > 0) {
+      if (!tsRecord.dataPointList.isEmpty()) {
         tsRecord.setTime(timestamp);
         collector.collect(tsRecord);
       }

iotdb-connector/flink-tsfile-connector/src/main/java/org/apache/iotdb/flink/tsfile/TsFileOutputFormat.java

@@ -53,7 +53,7 @@ public abstract class TsFileOutputFormat<T> extends FileOutputFormat<T> {
   @Nullable protected TSFileConfig config;
 
   protected transient Configuration hadoopConf = null;
-  private FileOutputStream fos = null;
+  private transient FileOutputStream fos = null;
   protected transient TsFileWriter writer = null;
 
   protected TsFileOutputFormat(String path, Schema schema, TSFileConfig config) {
@@ -77,7 +77,7 @@ public abstract class TsFileOutputFormat<T> extends FileOutputFormat<T> {
     // Use TsFile API to write instead of FSDataOutputStream.
     this.stream.close();
     Path actualFilePath = getAcutalFilePath();
-    TsFileOutput out;
+    TsFileOutput out = null;
     try {
       if (actualFilePath.getFileSystem().isDistributedFS()) {
         // HDFS

iotdb-connector/flink-tsfile-connector/src/main/java/org/apache/iotdb/flink/tsfile/util/TSFileConfigUtil.java

@@ -24,6 +24,7 @@ import org.apache.iotdb.tsfile.common.conf.TSFileDescriptor;
 
 /** Utils of setting global TSFileConfig. */
 public class TSFileConfigUtil {
+  private TSFileConfigUtil() {}
 
   public static void setGlobalTSFileConfig(TSFileConfig config) {
     TSFileConfig globalConfig = TSFileDescriptor.getInstance().getConfig();

iotdb-connector/grafana-connector/src/main/java/org/apache/iotdb/web/grafana/controller/DatabaseConnectController.java

@@ -33,9 +33,9 @@ import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.CrossOrigin;
+import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
-import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.bind.annotation.ResponseStatus;
 
@@ -59,7 +59,7 @@ public class DatabaseConnectController {
 
   @Autowired private DatabaseConnectService databaseConnectService;
 
-  @RequestMapping(value = "/", method = RequestMethod.GET)
+  @GetMapping(value = "/")
   @ResponseStatus(value = HttpStatus.OK)
   public void testDataConnection(HttpServletResponse response) throws IOException {
     logger.info("Connection is ok now!");

iotdb-connector/grafana-connector/src/main/java/org/apache/iotdb/web/grafana/dao/impl/BasicDaoImpl.java

@@ -101,7 +101,8 @@ public class BasicDaoImpl implements BasicDao {
       default:
         timestampRadioX = 1L;
     }
-    logger.info("Use timestamp precision {}", timestampPrecision.replaceAll("[\n\r\t]", "_"));
+    timestampPrecision = timestampPrecision.replaceAll("[\n\r\t]", "_");
+    logger.info("Use timestamp precision {}", timestampPrecision);
   }
 
   /**
@@ -164,7 +165,7 @@ public class BasicDaoImpl implements BasicDao {
   }
 
   public String getInterval(final long hours) {
-    if (!isDownSampling || !(hours > 1)) {
+    if (!isDownSampling || hours <= 1) {
       return "";
     }
 

iotdb-connector/grafana-connector/src/test/java/org/apache/iotdb/web/grafana/dao/impl/BasicDaoImplTest.java

@@ -19,6 +19,7 @@
 package org.apache.iotdb.web.grafana.dao.impl;
 
 import org.junit.After;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.springframework.test.util.ReflectionTestUtils;
@@ -38,15 +39,15 @@ public class BasicDaoImplTest {
     ReflectionTestUtils.setField(impl, "interval", "1m");
 
     String interval1 = impl.getInterval(0);
-    assert interval1.equals("");
+    Assert.assertEquals("", interval1);
 
     String interval2 = impl.getInterval(3);
-    assert interval2.equals("1m");
+    Assert.assertEquals("1m", interval2);
 
     String interval3 = impl.getInterval(25);
-    assert interval3.equals("1h");
+    Assert.assertEquals("1h", interval3);
 
     String interval4 = impl.getInterval(24 * 30 + 1);
-    assert interval4.equals("1d");
+    Assert.assertEquals("1d", interval4);
   }
 }

iotdb-connector/hadoop/src/main/java/org/apache/iotdb/hadoop/fileSystem/HDFSConfUtil.java

@@ -35,6 +35,8 @@ import java.net.MalformedURLException;
 
 class HDFSConfUtil {
 
+  private HDFSConfUtil() {}
+
   private static TSFileConfig tsFileConfig = TSFileDescriptor.getInstance().getConfig();
   private static final Logger logger = LoggerFactory.getLogger(HDFSConfUtil.class);
 

iotdb-connector/hadoop/src/main/java/org/apache/iotdb/hadoop/fileSystem/HDFSFile.java

@@ -28,6 +28,8 @@ import org.apache.hadoop.io.IOUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import javax.annotation.Nullable;
+
 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
 import java.io.BufferedReader;
@@ -48,8 +50,8 @@ import java.util.List;
 public class HDFSFile extends File {
 
   private static final long serialVersionUID = -8419827359081949547L;
-  private Path hdfsPath;
-  private FileSystem fs;
+  private transient Path hdfsPath;
+  private transient FileSystem fs;
   private static final Logger logger = LoggerFactory.getLogger(HDFSFile.class);
   private static final String UNSUPPORT_OPERATION = "Unsupported operation.";
 
@@ -117,7 +119,7 @@ public class HDFSFile extends File {
   }
 
   @Override
-  public File[] listFiles() {
+  public @Nullable File[] listFiles() {
     List<HDFSFile> files = new ArrayList<>();
     try {
       for (FileStatus fileStatus : fs.listStatus(hdfsPath)) {
@@ -230,7 +232,7 @@ public class HDFSFile extends File {
     }
   }
 
-  public BufferedWriter getBufferedWriter(String filePath, boolean append) {
+  public BufferedWriter getBufferedWriter(String filePath) {
     try {
       return new BufferedWriter(new OutputStreamWriter(fs.create(new Path(filePath))));
     } catch (IOException e) {

iotdb-connector/hadoop/src/main/java/org/apache/iotdb/hadoop/tsfile/TSFInputFormat.java

@@ -260,17 +260,18 @@ public class TSFInputFormat extends FileInputFormat<NullWritable, MapWritable> {
       if (length > 0) {
         FileSystem fileSystem = path.getFileSystem(configuration);
         logger.info("The file status is {}", fileStatus.getClass().getName());
-        logger.info("The file system is " + fileSystem.getClass());
+        logger.info("The file system is {}", fileSystem.getClass());
         blockLocations = fileSystem.getFileBlockLocations(fileStatus, 0, length);
 
-        logger.info("The block location information is {}", Arrays.toString(blockLocations));
+        String locationInfo = Arrays.toString(blockLocations);
+        logger.info("The block location information is {}", locationInfo);
         splits.addAll(generateSplits(path, blockLocations));
       } else {
-        logger.warn("The file length is " + length);
+        logger.warn("The file length is {}", length);
       }
     }
     configuration.setLong(NUM_INPUT_FILES, listFileStatus.size());
-    logger.info("The number of splits is " + splits.size());
+    logger.info("The number of splits is {}", splits.size());
 
     return splits;
   }

iotdb-connector/hadoop/src/main/java/org/apache/iotdb/hadoop/tsfile/TSFOutputFormat.java

@@ -35,7 +35,7 @@ import java.util.Objects;
 public class TSFOutputFormat extends FileOutputFormat<NullWritable, HDFSTSRecord> {
 
   private static final Logger logger = LoggerFactory.getLogger(TSFOutputFormat.class);
-  private static final String extension = "";
+  private static final String EXTENSION = "";
   private static Schema schema;
 
   public static Schema getSchema() {
@@ -50,7 +50,7 @@ public class TSFOutputFormat extends FileOutputFormat<NullWritable, HDFSTSRecord
   public RecordWriter<NullWritable, HDFSTSRecord> getRecordWriter(TaskAttemptContext job)
       throws IOException {
 
-    Path outputPath = getDefaultWorkFile(job, extension);
+    Path outputPath = getDefaultWorkFile(job, EXTENSION);
     logger.info(
         "The task attempt id is {}, the output path is {}", job.getTaskAttemptID(), outputPath);
     return new TSFRecordWriter(job, outputPath, Objects.requireNonNull(schema));

iotdb-connector/hadoop/src/main/java/org/apache/iotdb/hadoop/tsfile/TSFRecordReader.java

@@ -102,8 +102,8 @@ public class TSFRecordReader extends RecordReader<NullWritable, MapWritable> imp
     List<String> deviceIds = TSFInputFormat.getReadDeviceIds(configuration);
     List<String> measurementIds = TSFInputFormat.getReadMeasurementIds(configuration);
     readerSet.setMeasurementIds(measurementIds);
-    logger.info("deviceIds:" + deviceIds);
-    logger.info("Sensors:" + measurementIds);
+    logger.info("deviceIds: {}", deviceIds);
+    logger.info("Sensors: {}", measurementIds);
 
     readerSet.setReadDeviceId(TSFInputFormat.getReadDeviceId(configuration));
     readerSet.setReadTime(TSFInputFormat.getReadTime(configuration));

iotdb-connector/hive-connector/src/main/java/org/apache/iotdb/hive/TSFHiveRecordWriter.java

@@ -19,7 +19,6 @@
 package org.apache.iotdb.hive;
 
 import org.apache.iotdb.hadoop.fileSystem.HDFSOutput;
-import org.apache.iotdb.hadoop.tsfile.TSFRecordWriter;
 import org.apache.iotdb.hadoop.tsfile.record.HDFSTSRecord;
 import org.apache.iotdb.tsfile.exception.write.WriteProcessException;
 import org.apache.iotdb.tsfile.write.TsFileWriter;
@@ -40,7 +39,7 @@ import java.io.IOException;
  */
 public class TSFHiveRecordWriter implements FileSinkOperator.RecordWriter {
 
-  private static final Logger logger = LoggerFactory.getLogger(TSFRecordWriter.class);
+  private static final Logger logger = LoggerFactory.getLogger(TSFHiveRecordWriter.class);
 
   private TsFileWriter writer;
 

iotdb-connector/hive-connector/src/main/java/org/apache/iotdb/hive/TsFileSerDe.java

@@ -34,8 +34,6 @@ import org.apache.hadoop.hive.serde2.typeinfo.PrimitiveTypeInfo;
 import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
 import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoUtils;
 import org.apache.hadoop.io.Writable;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import javax.annotation.Nullable;
 
@@ -50,8 +48,6 @@ import static org.apache.iotdb.hadoop.tsfile.TSFInputFormat.READ_MEASUREMENTID;
 
 public class TsFileSerDe extends AbstractSerDe {
 
-  private static final Logger logger = LoggerFactory.getLogger(TsFileSerDe.class);
-
   public static final String DEVICE_ID = "device_id";
 
   private List<String> columnNames;

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/Executor.java

@@ -28,6 +28,7 @@ import java.util.List;
 
 /** This class used to execute Queries on TSFile */
 public class Executor {
+  private Executor() {}
 
   public static List<QueryDataSet> query(
       TsFileReader reader, List<QueryExpression> queryExpressions, long start, long end) {

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/QueryProcessor.java

@@ -129,7 +129,7 @@ public class QueryProcessor {
       return ret;
     }
     // a list of conjunctions linked by or
-    return filterOperator.childOperators;
+    return filterOperator.getChildOperators();
   }
 
   @SuppressWarnings("squid:S3776") // Suppress high Cognitive Complexity warning
@@ -169,16 +169,13 @@ public class QueryProcessor {
                 "The same key filter has been specified more than once: " + singlePath);
           }
         } else {
-          switch (child.getSinglePath()) {
-            case SQLConstant.RESERVED_TIME:
-              if (timeFilter != null) {
-                throw new QueryOperatorException("time filter has been specified more than once");
-              }
-              timeFilter = child;
-              break;
-            default:
-              valueList.add(child);
-              break;
+          if (SQLConstant.RESERVED_TIME.equals(child.getSinglePath())) {
+            if (timeFilter != null) {
+              throw new QueryOperatorException("time filter has been specified more than once");
+            }
+            timeFilter = child;
+          } else {
+            valueList.add(child);
           }
         }
       }
@@ -189,7 +186,7 @@ public class QueryProcessor {
 
     } else if (valueList.size() > 1) {
       valueFilter = new FilterOperator(SQLConstant.KW_AND, false);
-      valueFilter.childOperators = valueList;
+      valueFilter.setChildOperators(valueList);
     }
 
     return new SingleQuery(columnFilterOperators, timeFilter, valueFilter);

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/common/FilterOperator.java

@@ -30,7 +30,7 @@ import java.util.List;
  */
 public class FilterOperator extends Operator implements Comparable<FilterOperator> {
 
-  public List<FilterOperator> childOperators;
+  protected List<FilterOperator> childOperators;
   // leaf filter operator means it doesn't have left and right child filterOperator. Leaf filter
   // should be BasicOperator.
   protected boolean isLeaf = false;
@@ -95,6 +95,14 @@ public class FilterOperator extends Operator implements Comparable<FilterOperato
     return singlePath;
   }
 
+  public List<FilterOperator> getChildOperators() {
+    return childOperators;
+  }
+
+  public void setChildOperators(List<FilterOperator> childOperators) {
+    this.childOperators = childOperators;
+  }
+
   public void addChildOPerator(FilterOperator op) {
     childOperators.add(op);
   }

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/common/SQLConstant.java

@@ -23,6 +23,7 @@ import java.util.Map;
 
 /** this class contains several constants used in SQL. */
 public class SQLConstant {
+  private SQLConstant() {}
 
   public static final String DELTA_OBJECT_NAME = "delta_object_name";
   public static final String REGEX_PATH_SEPARATOR = "\\.";
@@ -72,70 +73,62 @@ public class SQLConstant {
   public static final int TOK_PROPERTY_LINK = 57;
   public static final int TOK_PROPERTY_UNLINK = 58;
 
-  public static final Map<Integer, String> tokenSymbol =
-      new HashMap<Integer, String>() {
-        {
-          put(KW_AND, "&");
-          put(KW_OR, "|");
-          put(KW_NOT, "!");
-          put(EQUAL, "=");
-          put(NOTEQUAL, "<>");
-          put(EQUAL_NS, "<=>");
-          put(LESSTHANOREQUALTO, "<=");
-          put(LESSTHAN, "<");
-          put(GREATERTHANOREQUALTO, ">=");
-          put(GREATERTHAN, ">");
-        }
-      };
+  protected static final Map<Integer, String> tokenSymbol = new HashMap<Integer, String>() {};
+  public static final Map<Integer, String> tokenNames = new HashMap<Integer, String>() {};
+  public static final Map<Integer, Integer> reverseWords = new HashMap<Integer, Integer>() {};
 
-  public static final Map<Integer, String> tokenNames =
-      new HashMap<Integer, String>() {
-        {
-          put(KW_AND, "and");
-          put(KW_OR, "or");
-          put(KW_NOT, "not");
-          put(EQUAL, "equal");
-          put(NOTEQUAL, "not_equal");
-          put(EQUAL_NS, "equal_ns");
-          put(LESSTHANOREQUALTO, "lessthan_or_equalto");
-          put(LESSTHAN, "lessthan");
-          put(GREATERTHANOREQUALTO, "greaterthan_or_equalto");
-          put(GREATERTHAN, "greaterthan");
-          put(TOK_SELECT, "TOK_SELECT");
-          put(TOK_FROM, "TOK_FROM");
-          put(TOK_WHERE, "TOK_WHERE");
-          put(TOK_INSERT, "TOK_INSERT");
-          put(TOK_DELETE, "TOK_DELETE");
-          put(TOK_UPDATE, "TOK_UPDATE");
-          put(TOK_QUERY, "TOK_QUERY");
-          put(TOK_AUTHOR_CREATE, "TOK_AUTHOR_CREATE");
-          put(TOK_AUTHOR_DROP, "TOK_AUTHOR_DROP");
-          put(TOK_AUTHOR_GRANT, "TOK_AUTHOR_GRANT");
-          put(TOK_AUTHOR_REVOKE, "TOK_AUTHOR_REVOKE");
-          put(TOK_DATALOAD, "TOK_DATALOAD");
-          put(TOK_METADATA_CREATE, "TOK_METADATA_CREATE");
-          put(TOK_METADATA_DELETE, "TOK_METADATA_DELETE");
-          put(TOK_METADATA_SET_FILE_LEVEL, "TOK_METADATA_SET_FILE_LEVEL");
-          put(TOK_PROPERTY_CREATE, "TOK_PROPERTY_CREATE");
-          put(TOK_PROPERTY_ADD_LABEL, "TOK_PROPERTY_ADD_LABEL");
-          put(TOK_PROPERTY_DELETE_LABEL, "TOK_PROPERTY_DELETE_LABEL");
-          put(TOK_PROPERTY_LINK, "TOK_PROPERTY_LINK");
-          put(TOK_PROPERTY_UNLINK, "TOK_PROPERTY_UNLINK");
-        }
-      };
-  public static final Map<Integer, Integer> reverseWords =
-      new HashMap<Integer, Integer>() {
-        {
-          put(KW_AND, KW_OR);
-          put(KW_OR, KW_AND);
-          put(EQUAL, NOTEQUAL);
-          put(NOTEQUAL, EQUAL);
-          put(LESSTHAN, GREATERTHANOREQUALTO);
-          put(GREATERTHANOREQUALTO, LESSTHAN);
-          put(LESSTHANOREQUALTO, GREATERTHAN);
-          put(GREATERTHAN, LESSTHANOREQUALTO);
-        }
-      };
+  static {
+    tokenSymbol.put(KW_AND, "&");
+    tokenSymbol.put(KW_OR, "|");
+    tokenSymbol.put(KW_NOT, "!");
+    tokenSymbol.put(EQUAL, "=");
+    tokenSymbol.put(NOTEQUAL, "<>");
+    tokenSymbol.put(EQUAL_NS, "<=>");
+    tokenSymbol.put(LESSTHANOREQUALTO, "<=");
+    tokenSymbol.put(LESSTHAN, "<");
+    tokenSymbol.put(GREATERTHANOREQUALTO, ">=");
+    tokenSymbol.put(GREATERTHAN, ">");
+
+    tokenNames.put(KW_AND, "and");
+    tokenNames.put(KW_OR, "or");
+    tokenNames.put(KW_NOT, "not");
+    tokenNames.put(EQUAL, "equal");
+    tokenNames.put(NOTEQUAL, "not_equal");
+    tokenNames.put(EQUAL_NS, "equal_ns");
+    tokenNames.put(LESSTHANOREQUALTO, "lessthan_or_equalto");
+    tokenNames.put(LESSTHAN, "lessthan");
+    tokenNames.put(GREATERTHANOREQUALTO, "greaterthan_or_equalto");
+    tokenNames.put(GREATERTHAN, "greaterthan");
+    tokenNames.put(TOK_SELECT, "TOK_SELECT");
+    tokenNames.put(TOK_FROM, "TOK_FROM");
+    tokenNames.put(TOK_WHERE, "TOK_WHERE");
+    tokenNames.put(TOK_INSERT, "TOK_INSERT");
+    tokenNames.put(TOK_DELETE, "TOK_DELETE");
+    tokenNames.put(TOK_UPDATE, "TOK_UPDATE");
+    tokenNames.put(TOK_QUERY, "TOK_QUERY");
+    tokenNames.put(TOK_AUTHOR_CREATE, "TOK_AUTHOR_CREATE");
+    tokenNames.put(TOK_AUTHOR_DROP, "TOK_AUTHOR_DROP");
+    tokenNames.put(TOK_AUTHOR_GRANT, "TOK_AUTHOR_GRANT");
+    tokenNames.put(TOK_AUTHOR_REVOKE, "TOK_AUTHOR_REVOKE");
+    tokenNames.put(TOK_DATALOAD, "TOK_DATALOAD");
+    tokenNames.put(TOK_METADATA_CREATE, "TOK_METADATA_CREATE");
+    tokenNames.put(TOK_METADATA_DELETE, "TOK_METADATA_DELETE");
+    tokenNames.put(TOK_METADATA_SET_FILE_LEVEL, "TOK_METADATA_SET_FILE_LEVEL");
+    tokenNames.put(TOK_PROPERTY_CREATE, "TOK_PROPERTY_CREATE");
+    tokenNames.put(TOK_PROPERTY_ADD_LABEL, "TOK_PROPERTY_ADD_LABEL");
+    tokenNames.put(TOK_PROPERTY_DELETE_LABEL, "TOK_PROPERTY_DELETE_LABEL");
+    tokenNames.put(TOK_PROPERTY_LINK, "TOK_PROPERTY_LINK");
+    tokenNames.put(TOK_PROPERTY_UNLINK, "TOK_PROPERTY_UNLINK");
+
+    reverseWords.put(KW_AND, KW_OR);
+    reverseWords.put(KW_OR, KW_AND);
+    reverseWords.put(EQUAL, NOTEQUAL);
+    reverseWords.put(NOTEQUAL, EQUAL);
+    reverseWords.put(LESSTHAN, GREATERTHANOREQUALTO);
+    reverseWords.put(GREATERTHANOREQUALTO, LESSTHAN);
+    reverseWords.put(LESSTHANOREQUALTO, GREATERTHAN);
+    reverseWords.put(GREATERTHAN, LESSTHANOREQUALTO);
+  }
 
   public static boolean isReservedPath(String pathStr) {
     return pathStr.equals(SQLConstant.RESERVED_TIME)

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/exception/QueryProcessorException.java

@@ -23,7 +23,7 @@ public class QueryProcessorException extends Exception {
 
   private static final long serialVersionUID = -8987915921329335088L;
 
-  private String errMsg;
+  private final String errMsg;
 
   QueryProcessorException(String msg) {
     super(msg);

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/optimizer/DNFFilterOptimizer.java

@@ -113,14 +113,13 @@ public class DNFFilterOptimizer implements IFilterOptimizer {
    * @return List<FilterOperator>
    */
   private List<FilterOperator> getAndChild(FilterOperator child) {
-    switch (child.getTokenIntType()) {
-      case KW_OR:
-        return child.getChildren();
-      default:
-        // other token type means leaf node or "and" operator
-        List<FilterOperator> ret = new ArrayList<>();
-        ret.add(child);
-        return ret;
+    if (KW_OR == child.getTokenIntType()) {
+      return child.getChildren();
+    } else {
+      // other token type means leaf node or "and" operator
+      List<FilterOperator> ret = new ArrayList<>();
+      ret.add(child);
+      return ret;
     }
   }
 

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/optimizer/MergeSingleFilterOptimizer.java

@@ -18,7 +18,6 @@
  */
 package org.apache.iotdb.spark.tsfile.qp.optimizer;
 
-import org.apache.iotdb.spark.tsfile.qp.common.BasicOperator;
 import org.apache.iotdb.spark.tsfile.qp.common.FilterOperator;
 import org.apache.iotdb.spark.tsfile.qp.exception.MergeFilterException;
 
@@ -131,13 +130,4 @@ public class MergeSingleFilterOptimizer implements IFilterOptimizer {
       return null;
     }
   }
-
-  private boolean allIsBasic(List<FilterOperator> children) {
-    for (FilterOperator child : children) {
-      if (!(child instanceof BasicOperator)) {
-        return false;
-      }
-    }
-    return true;
-  }
 }

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/optimizer/PhysicalOptimizer.java

@@ -99,7 +99,7 @@ public class PhysicalOptimizer {
     }
 
     // query all measurements from TSFile
-    if (selectedSeries.size() == 0) {
+    if (selectedSeries.isEmpty()) {
       selectedSeries.addAll(allMeasurementsInFile.keySet());
     } else {
       // remove paths that doesn't exist in file
@@ -143,10 +143,10 @@ public class PhysicalOptimizer {
     // which should in column names -> now just device_name
     // use delta_object column
     if (columnValues.containsKey(SQLConstant.RESERVED_DELTA_OBJECT)) {
-      Set<String> delta_objects = columnValues.get(SQLConstant.RESERVED_DELTA_OBJECT);
-      for (String delta_object : delta_objects) {
-        if (actualDeltaObjects.contains(delta_object)) {
-          validDeltaObjects.add(delta_object);
+      Set<String> deltaObjects = columnValues.get(SQLConstant.RESERVED_DELTA_OBJECT);
+      for (String deltaObject : deltaObjects) {
+        if (actualDeltaObjects.contains(deltaObject)) {
+          validDeltaObjects.add(deltaObject);
         }
       }
       return;
@@ -178,14 +178,14 @@ public class PhysicalOptimizer {
   }
 
   private Map<String, Set<String>> mergeColumns(List<FilterOperator> columnFilterOperators) {
-    Map<String, Set<String>> column_values_map = new HashMap<>();
+    Map<String, Set<String>> columnValuesMap = new HashMap<>();
     for (FilterOperator filterOperator : columnFilterOperators) {
-      Pair<String, Set<String>> column_values = mergeColumn(filterOperator);
-      if (column_values != null && !column_values.right.isEmpty()) {
-        column_values_map.put(column_values.left, column_values.right);
+      Pair<String, Set<String>> columnValues = mergeColumn(filterOperator);
+      if (columnValues != null && !columnValues.right.isEmpty()) {
+        columnValuesMap.put(columnValues.left, columnValues.right);
       }
     }
-    return column_values_map;
+    return columnValuesMap;
   }
 
   /**

iotdb-connector/spark-tsfile/src/main/java/org/apache/iotdb/spark/tsfile/qp/optimizer/RemoveNotOptimizer.java

@@ -23,9 +23,6 @@ import org.apache.iotdb.spark.tsfile.qp.common.FilterOperator;
 import org.apache.iotdb.spark.tsfile.qp.common.SQLConstant;
 import org.apache.iotdb.spark.tsfile.qp.exception.RemoveNotException;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.List;
 
 import static org.apache.iotdb.spark.tsfile.qp.common.SQLConstant.KW_AND;
@@ -34,8 +31,6 @@ import static org.apache.iotdb.spark.tsfile.qp.common.SQLConstant.KW_OR;
 
 public class RemoveNotOptimizer implements IFilterOptimizer {
 
-  private static final Logger LOG = LoggerFactory.getLogger(RemoveNotOptimizer.class);
-
   /**
    * get DNF(disjunctive normal form) for this filter operator tree. Before getDNF, this op tree
    * must be binary, in another word, each non-leaf node has exactly two children.

iotdb-connector/spark-tsfile/src/main/scala/org/apache/iotdb/spark/tsfile/NarrowConverter.scala

@@ -310,7 +310,7 @@ object NarrowConverter extends Converter {
         throw new Exception("NOT filter is not supported now")
 
       case SQLConstant.KW_AND =>
-        node.childOperators.foreach((child: FilterOperator) => {
+        node.getChildOperators.foreach((child: FilterOperator) => {
           if (filter == null) {
             filter = transformFilterToExpression(schema, child, device_name)
           }
@@ -322,7 +322,7 @@ object NarrowConverter extends Converter {
         filter
 
       case SQLConstant.KW_OR =>
-        node.childOperators.foreach((child: FilterOperator) => {
+        node.getChildOperators.foreach((child: FilterOperator) => {
           if (filter == null) {
             filter = transformFilterToExpression(schema, child, device_name)
           }