Add Javadoc, use common findColumn implementation.

Addresses code review comments.

src/main/java/net/starschema/clouddb/jdbc/BQForwardOnlyResultSet.java

@@ -586,29 +586,10 @@ public void deleteRow() throws SQLException {
     throw new BQSQLFeatureNotSupportedException("deleteRow()");
   }
 
-  /**
-   *
-   *
-   * <h1>Implementation Details:</h1>
-   *
-   * <br>
-   * Not implemented yet.
-   *
-   * @throws BQSQLException
-   */
+  /** {@inheritDoc} */
   @Override
   public int findColumn(String columnLabel) throws SQLException {
-    if (isClosed()) {
-      throw new BQSQLException("This Resultset is Closed");
-    }
-    final ResultSetMetaData metadata = this.getMetaData();
-    int columns = metadata.getColumnCount();
-    for (int i = 1; i <= columns; i++) {
-      if (metadata.getColumnLabel(i).equals(columnLabel)) {
-        return i;
-      }
-    }
-    throw new BQSQLException("No Such column labeled: " + columnLabel);
+    return CommonResultSet.findColumn(columnLabel, getMetaData());
   }
 
   /**

src/main/java/net/starschema/clouddb/jdbc/BQResultSet.java

@@ -109,18 +109,7 @@ public BQResultSet(
   /** {@inheritDoc} */
   @Override
   public int findColumn(String columnLabel) throws SQLException {
-    if (this.isClosed()) {
-      throw new BQSQLException("This Resultset is Closed");
-    }
-    final ResultSetMetaData metadata = this.getMetaData();
-    int columns = metadata.getColumnCount();
-    for (int i = 1; i <= columns; i++) {
-      if (metadata.getColumnLabel(i).equals(columnLabel)) {
-        return i;
-      }
-    }
-    SQLException e = new BQSQLException("No Such column labeled: " + columnLabel);
-    throw e;
+    return CommonResultSet.findColumn(columnLabel, getMetaData());
   }
 
   /** {@inheritDoc} */

src/main/java/net/starschema/clouddb/jdbc/BQScrollableResultSet.java

@@ -137,17 +137,7 @@ public BQScrollableResultSet(
   /** {@inheritDoc} */
   @Override
   public int findColumn(String columnLabel) throws SQLException {
-    if (this.isClosed()) {
-      throw new BQSQLException("This Resultset is Closed");
-    }
-    final ResultSetMetaData metadata = this.getMetaData();
-    int columns = metadata.getColumnCount();
-    for (int i = 1; i <= columns; i++) {
-      if (metadata.getColumnLabel(i).equals(columnLabel)) {
-        return i;
-      }
-    }
-    throw new BQSQLException("No Such column labeled: " + columnLabel);
+    return CommonResultSet.findColumn(columnLabel, getMetaData());
   }
 
   /** {@inheritDoc} */

src/main/java/net/starschema/clouddb/jdbc/CommonResultSet.java

@@ -0,0 +1,27 @@
+package net.starschema.clouddb.jdbc;
+
+import com.google.cloud.bigquery.BigQuerySQLException;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+
+/** A static utility class of methods common to all {@link java.sql.ResultSet} implementations. */
+class CommonResultSet {
+
+  /**
+   * A common implementation of {@link java.sql.ResultSet#findColumn(String)}
+   *
+   * @param label the column-to-find's label
+   * @param metadata the metadata from the {@link java.sql.ResultSet}
+   * @return the integer index of the labeled column, if it's found
+   * @throws SQLException if no column with the given label is found
+   */
+  static int findColumn(final String label, final ResultSetMetaData metadata) throws SQLException {
+    int columnCount = metadata.getColumnCount();
+    for (int column = 1; column <= columnCount; column++) {
+      if (metadata.getColumnLabel(column).equals(label)) {
+        return column;
+      }
+    }
+    throw new BigQuerySQLException("No such Column labeled: " + label);
+  }
+}

src/test/java/net/starschema/clouddb/jdbc/CommonTestsForResultSets.java

@@ -22,6 +22,13 @@
 import org.junit.Before;
 import org.junit.Test;
 
+/**
+ * An abstract class that contains tests common to {@link ResultSet} implementations. Its name
+ * doesn't end with Test so that JUnit doesn't try to run it.
+ *
+ * <p>Subclass this in @{link ResultSet} test classes and implement {@link
+ * CommonTestsForResultSets#createStatementForCommonTests(Connection)}.
+ */
 public abstract class CommonTestsForResultSets {
 
   private Connection connection;