All the fields of a class are accessible via the Class.getDeclaredFields() method. This method returns an array of Field:

Field[] fields = clazz.getDeclaredFields();

// final java.lang.Object modern.challenge.Pair.left
// final java.lang.Object modern.challenge.Pair.right
System.out.println("Fields: " + Arrays.toString(fields));

For fetching the actual name of the fields, we can easily provide a helper method:

public static List<String> getFieldNames(Field[] fields) {

  return Arrays.stream(fields)
    .map(Field::getName)
    .collect(Collectors.toList());
}

Now, we only receive the names of the fields:

List<String> fieldsName = getFieldNames(fields);

// left, right
System.out.println("Fields names: " + fieldsName);

Getting the value of a field can be done via a general method named Object get(Object obj) and via a set of getFoo() methods (consider documentation for details). The obj represents a static or instance field. For example, let's assume the ProcedureOutputs class that have has a private field named callableStatement which is of type CallableStatement. Let's use Field.get() method to access this field for checking if the CallableStatement is closed:

ProcedureOutputs procedureOutputs 
  = storedProcedure.unwrap(ProcedureOutputs.class);

Field csField = procedureOutputs.getClass()
  .getDeclaredField("callableStatement"); 
csField.setAccessible(true);

CallableStatement cs 
  = (CallableStatement) csField.get(procedureOutputs);

System.out.println("Is closed? " + cs.isClosed());