select 'colname' from schemaname.tablename

String url = "jdbc:db2://host:50000/yourdb";
Properties props = new Properties();
props.setProperty("useJDBC4ColumnNameAndLabelSemantics", "2");
// set other required properties
Connection c = DriverManager.getConnection(url, props);

String url = "jdbc:db2://host:50000/yourdb:useJDBC4ColumnNameAndLabelSemantics=2;";
// set other required properties
Connection c = DriverManager.getConnection(url);