Java class for getting general info (table and column names) from SQLite Databases

DBReader.java

package countit.db;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public final class Table
{
    private final Set<String> _names;
    private final Map<String, Set<String>> _columns;
    private final Map<String, Integer> _numberOfRecords;
    private final String _string;
    private final int _hashCode;

    public Table(Connection dbConnection) throws SQLException
    {
        final ResultSet tablesResultSet =
            dbConnection.getMetaData().getTables(null, null, null, new String[]{"TABLE"});
        final Map<String, Set<String>> columnNames = new HashMap<>();
        final Map<String, Integer> numberOfRecords = new HashMap<>();

        while (tablesResultSet.next())
        {
            final String tableName = tablesResultSet.getString("Table_NAME");
            final ResultSet columnsResultSet =
                dbConnection.getMetaData().getColumns(null, null, tableName, null);

            final HashSet<String> columnNamesSet = new HashSet<>();

            while (columnsResultSet.next())
            {
                columnNamesSet.add(columnsResultSet.getString("COLUMN_NAME"));
            }

            columnNames.put(tableName, columnNamesSet);
            numberOfRecords.put(tableName, columnNamesSet.size());

        }

        this._columns = Collections.unmodifiableMap(columnNames);
        this._names = Collections.unmodifiableSet(columnNames.keySet());
        this._numberOfRecords =  Collections.unmodifiableMap(numberOfRecords);
        this._hashCode = this._columns.hashCode();
        this._string = Table.class.getSimpleName() + '(' + this._names.size() + ") " + this._columns.toString();
    }

    public Set<String> getTableNames() { return this._names; }
    public Map<String, Set<String>> getColumnNames() { return this._columns; }
    public Map<String, Integer> getNumberOfRecords() { return this._numberOfRecords; }

    @Override
    public boolean equals(Object obj)
    {
        if (this == obj) { return true; }
        if (obj == null) {return false; }
        if ( ! (obj instanceof Table)) { return false; }

        return this._columns.equals(((Table) obj)._columns);
    }

    @Override
    public int hashCode() { return this._hashCode; }

    @Override
    public String toString() { return this._string; }

    public static Table connectionFromUrl(String url) throws SQLException
    {
        return new Table(DriverManager.getConnection(url));
    }

    public static Table connectionFromUrl(String url, String user, String password) throws SQLException
    {
        return new Table(DriverManager.getConnection(url, user, password));
    }

    public static Table connectionFromUrl(String url, Properties info) throws SQLException
    {
        return new Table(DriverManager.getConnection(url, info));
    }
}