Fix NPE for incomplete JDBC URLs

NEXT_CHANGELOG.md

@@ -8,6 +8,9 @@
 - `DatabaseMetaData.getColumns(...)` with a `null` catalog now issues a single `SHOW COLUMNS IN ALL CATALOGS` statement (consistent with `getSchemas`/`getTables`) instead of enumerating every catalog and issuing a per-catalog `SHOW COLUMNS`. Older DBR versions that do not support the syntax transparently fall back to the previous enumerate-and-fan-out behavior.
 
 ### Fixed
+- Invalid or incomplete Databricks JDBC URLs now fail with a descriptive `DatabricksSQLException`
+  instead of leaking a `NullPointerException` when required connection parameters are missing.
+
 - Fixed `IdleConnectionEvictor` thread leak in long-running applications. Driver-side resources (HTTP client, background threads) are now always released when `Connection.close()` is called, even if statement cleanup or server-side session termination fails.
 
 - Throw `DatabricksSQLException` instead of an unchecked `ClassCastException` when a complex-type getter (`getArray`, `getStruct`, `getMap`) is called on a column of a different complex type.

src/main/java/com/databricks/jdbc/common/util/ValidationUtil.java

@@ -148,6 +148,10 @@ public static void checkHTTPError(HttpResponse response)
    * @return true if the URL is valid, false otherwise
    */
   public static boolean isValidJdbcUrl(String url) {
+    if (url == null) {
+      return false;
+    }
+
     final List<Pattern> PATH_PATTERNS =
         List.of(
             HTTP_CLUSTER_PATH_PATTERN,
@@ -176,11 +180,30 @@ public static boolean isValidJdbcUrl(String url) {
    */
   public static void validateInputProperties(Map<String, String> parameters)
       throws DatabricksValidationException {
+    validateRequiredConnectionParameters(parameters);
     // Fail fast on an unsupported AuthMech before the client-configurator machinery runs.
     validateAuthMech(parameters);
     validateUidParameter(parameters);
   }
 
+  /**
+   * Validates parameters that must be present in every connection configuration. URL parameters and
+   * {@link java.util.Properties} are merged before this method is called, so required values may be
+   * supplied through either mechanism.
+   *
+   * @param parameters merged JDBC connection parameters
+   * @throws DatabricksValidationException if any required parameter is missing or blank
+   */
+  private static void validateRequiredConnectionParameters(Map<String, String> parameters)
+      throws DatabricksValidationException {
+    String parameterName = DatabricksJdbcUrlParams.HTTP_PATH.getParamName().toLowerCase();
+    String httpPath = parameters.get(parameterName);
+    if (httpPath == null || httpPath.isBlank()) {
+      throw new DatabricksValidationException(
+          "Missing required connection parameter: " + parameterName);
+    }
+  }
+
   /**
    * Validates the AuthMech parameter. Reuses {@link AuthMech#fromValue} as the single source of
    * truth for supported values, so adding a new AuthMech only requires updating {@code AuthMech}.

src/test/java/com/databricks/client/jdbc/DriverTest.java

@@ -0,0 +1,24 @@
+package com.databricks.client.jdbc;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.databricks.jdbc.exception.DatabricksSQLException;
+import java.util.Properties;
+import org.junit.jupiter.api.Test;
+
+class DriverTest {
+
+  @Test
+  void connectRejectsMissingRequiredConnectionParameters() {
+    DatabricksSQLException exception =
+        assertThrows(
+            DatabricksSQLException.class,
+            () ->
+                Driver.getInstance().connect("jdbc:databricks://localhost:8080", new Properties()));
+
+    assertEquals("INPUT_VALIDATION_ERROR", exception.getSQLState());
+    assertTrue(exception.getMessage().contains("httppath"));
+  }
+}

src/test/java/com/databricks/jdbc/api/impl/DatabricksConnectionContextTest.java

@@ -33,6 +33,7 @@
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.ValueSource;
 
 class DatabricksConnectionContextTest {
 
@@ -85,6 +86,26 @@ public void testParseInvalid() {
     assertThrows(
         DatabricksParsingException.class,
         () -> DatabricksConnectionContext.parse(TestConstants.INVALID_URL_2, properties));
+    assertThrows(
+        DatabricksParsingException.class,
+        () -> DatabricksConnectionContext.parse(null, properties));
+  }
+
+  @ParameterizedTest
+  @ValueSource(
+      strings = {
+        "jdbc:databricks://localhost:8080",
+        "jdbc:databricks://localhost:8080;httpPath=",
+        "jdbc:databricks://localhost:8080;httpPath= "
+      })
+  public void testParseRejectsMissingRequiredConnectionParameters(String url) {
+    DatabricksSQLException exception =
+        assertThrows(
+            DatabricksSQLException.class,
+            () -> DatabricksConnectionContext.parse(url, new Properties()));
+
+    assertEquals("INPUT_VALIDATION_ERROR", exception.getSQLState());
+    assertTrue(exception.getMessage().contains("httppath"));
   }
 
   @Test