[TD-6809]: Fix jdbc NPE (#6814)

.gitignore

@@ -68,6 +68,8 @@ CMakeError.log
 *.o
 version.c
 taos.rc
+src/connector/jdbc/.classpath
+src/connector/jdbc/.project
 src/connector/jdbc/.settings/
 tests/comparisonTest/cassandra/cassandratest/.classpath
 tests/comparisonTest/cassandra/cassandratest/.project

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBPreparedStatement.java

@@ -57,8 +57,8 @@ public class TSDBPreparedStatement extends TSDBStatement implements PreparedStat
                     parameterCnt++;
                 }
             }
-            parameters = new Object[parameterCnt];
         }
+        parameters = new Object[parameterCnt];
 
         if (parameterCnt > 1) {
             // the table name is also a parameter, so ignore it.

src/connector/jdbc/src/main/java/com/taosdata/jdbc/rs/RestfulPreparedStatement.java

@@ -22,16 +22,16 @@ public class RestfulPreparedStatement extends RestfulStatement implements Prepar
         super(conn, database);
         this.rawSql = sql;
 
-        if (sql.contains("?")) {
         int parameterCnt = 0;
+        if (sql.contains("?")) {
             for (int i = 0; i < sql.length(); i++) {
                 if ('?' == sql.charAt(i)) {
                     parameterCnt++;
                 }
             }
-            parameters = new Object[parameterCnt];
             this.isPrepared = true;
         }
+        parameters = new Object[parameterCnt];
 
         // build parameterMetaData
         this.parameterMetaData = new RestfulParameterMetaData(parameters);

src/connector/jdbc/src/test/java/com/taosdata/jdbc/rs/RestfulPreparedStatementTest.java

@@ -15,6 +15,8 @@ public class RestfulPreparedStatementTest {
     private static PreparedStatement pstmt_insert;
     private static final String sql_select = "select * from t1 where ts > ? and ts <= ? and f1 >= ?";
     private static PreparedStatement pstmt_select;
+    private static final String sql_without_parameters = "select count(*) from t1";
+    private static PreparedStatement pstmt_without_parameters;
 
     @Test
     public void executeQuery() throws SQLException {
@@ -237,6 +239,7 @@ public class RestfulPreparedStatementTest {
     @Test
     public void clearParameters() throws SQLException {
         pstmt_insert.clearParameters();
+        pstmt_without_parameters.clearParameters();
     }
 
     @Test
@@ -382,6 +385,7 @@ public class RestfulPreparedStatementTest {
 
             pstmt_insert = conn.prepareStatement(sql_insert);
             pstmt_select = conn.prepareStatement(sql_select);
+            pstmt_without_parameters = conn.prepareStatement(sql_without_parameters);
         } catch (SQLException e) {
             e.printStackTrace();
         }
@@ -394,6 +398,8 @@ public class RestfulPreparedStatementTest {
                 pstmt_insert.close();
             if (pstmt_select != null)
                 pstmt_select.close();
+            if (pstmt_without_parameters != null)
+                pstmt_without_parameters.close();
             if (conn != null)
                 conn.close();
         } catch (SQLException e) {