You can use ResultSetMetaData to retrieve metadata about the results of a query.

The query can contain any of the following:

• Aliases
• Fully qualified names
• Generated columns

You can instantiate a ResultSetMetaData object by invoking the getMetaData method of the Statement class. A ResultSetMetaData instance is populated with data after the statement has been executed. The following query prints out the columns in the result of the query:

String connectionString = "jdbc:postgresql:User=postgres;Password=admin;Database=postgres;Server=127.0.0.1;Port=5432";

Connection conn = DriverManager.getConnection(connectionString);
PreparedStatement pstmt = conn.prepareStatement("SELECT ShipName, ShipCity AS My_ShipCity, GETDATE() FROM \"postgres\".\"schema01\".Orders WHERE ShipCountry = 'USA'");
pstmt.executeQuery();
ResultSetMetaData rs = pstmt.getMetaData();
for(int i=1;i<=rs.getColumnCount();i++) {
  System.out.println(rs.getColumnName(i));
}