Get Field List By Type

getFieldsOfType.apex

public Map<String,String> handleDateTypes(Map<String,String>  recordMap,Type classType){

        List<String> dateTimeFields = getFieldsOfType(
              classType
            , Schema.SOAPType.DATE
        );

        for( String fieldKey : recordMap.keySet() ){
            if( dateTimeFields.contains(fieldKey.toLowerCase()) ){
                String dateValue = recordMap.get(fieldKey);
                if( String.isBlank(dateValue) || 'null'.equalsIgnoreCase(dateValue) ){
                    recordMap.put(fieldKey,null);
                } else {
                    //create a date instance out of the milliseconds
                    Date dateInstance = Date.parse(dateValue);
                    //recordMap.put(fieldKey,dateInstance.toString());
                }
            }
        }

        return recordMap;
    }

    //list of all the fields of a particular type
    public static List<String> getAllFields(Type classType){
        Set<Schema.SOAPType> soapTypeSet = null;
        return getFieldsOfType(classType,soapTypeSet);
    }

    public static List<String> getFieldsOfType(Type classType,Schema.SOAPType soapType){
        return getFieldsOfType(classType,new Set<Schema.SOAPType>{soapType});
    }

    public static List<String> getFieldsOfType(Type classType,Set<Schema.SOAPType> soapTypeSet){

        Map<String, Schema.SObjectField> fieldMap;
        Schema.DescribeFieldResult fieldDescribeResult;
        List<String> fieldList = new List<String>();

        Schema.SObjectType sObjectType = getSObjectType(classType.toString());

        if( sObjectType != null ) {
            fieldMap = sObjectType.getDescribe().fields.getMap();
            
            for(String fieldName : fieldMap.keySet()){
                fieldDescribeResult = fieldMap.get(fieldName).getDescribe();
                if( soapTypeSet == null) {
                    fieldList.add(fieldName);
                } else if( soapTypeSet.contains(fieldDescribeResult.getSOAPType())  ){
                    fieldList.add(fieldName);
                }  
            }

        }

        return fieldList;
    }