You may be reinventing the wheel. I believe what you're looking for already exists in the SetUtils Class
of the ApexLang Repo on GitHub. I think the pluckString
methods may be along the lines of what you're looking for. See the code below.
/* ============================================================
* This code is part of the "apex-lang" open source project avaiable at:
*
* http://code.google.com/p/apex-lang/
*
* This code is licensed under the Apache License, Version 2.0. You may obtain a
* copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
* ============================================================
*/
global class SetUtils {
global static Set<Blob> objectToBlob(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Blob> blobSet = new Set<Blob>();
for(Object anObject : objectSet){
if(anObject instanceof Blob){
blobSet.add((Blob)anObject);
}
}
return blobSet;
}
global static Set<Boolean> objectToBoolean(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Boolean> booleanSet = new Set<Boolean>();
for(Object anObject : objectSet){
if(anObject instanceof Boolean){
booleanSet.add((Boolean)anObject);
}
}
return booleanSet;
}
global static Set<Date> objectToDate(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Date> dateSet = new Set<Date>();
for(Object anObject : objectSet){
if(anObject instanceof Date){
dateSet.add((Date)anObject);
}
}return dateSet;
}
global static Set<Datetime> objectToDatetime(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Datetime> datetimeSet = new Set<Datetime>();
for(Object anObject : objectSet){
if(anObject instanceof Datetime){
datetimeSet.add((Datetime)anObject);
}
}
return datetimeSet;
}
global static Set<Decimal> objectToDecimal(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Decimal> decimalSet = new Set<Decimal>();
for(Object anObject : objectSet){
if(anObject instanceof Decimal){
decimalSet.add((Decimal)anObject);
}
}
return decimalSet;
}
global static Set<Double> objectToDouble(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Double> doubleSet = new Set<Double>();
for(Object anObject : objectSet){
if(anObject instanceof Double){
doubleSet.add((Double)anObject);
}
}return doubleSet;
}
global static Set<ID> objectToID(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<ID> idSet = new Set<ID>();
for(Object anObject : objectSet){
if(anObject instanceof ID){
idSet.add((ID)anObject);
}
}
return idSet;
}
global static Set<Integer> objectToInteger(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Integer> integerSet = new Set<Integer>();
for(Object anObject : objectSet){
if(anObject instanceof Integer){
integerSet.add((Integer)anObject);
}
}
return integerSet;
}
global static Set<Long> objectToLong(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Long> longSet = new Set<Long>();
for(Object anObject : objectSet){
if(anObject instanceof Long){
longSet.add((Long)anObject);
}
}
return longSet;
}
global static Set<Time> objectToTime(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<Time> timeSet = new Set<Time>();
for(Object anObject : objectSet){
if(anObject instanceof Time){
timeSet.add((Time)anObject);
}
}
return timeSet;
}
global static Set<String> objectToString(Set<Object> objectSet){
if(objectSet == null){
return null;
}
Set<String> stringSet = new Set<String>();
for(Object anObject : objectSet){
if(anObject instanceof String){
stringSet.add((String)anObject);
}
}
return stringSet;
}
global static Set<Object> blobToObject(Set<Blob> blobSet){
if(blobSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Blob aBlob : blobSet){
objectSet.add(aBlob);
}
return objectSet;
}
global static Set<Object> booleanToObject(Set<Boolean> booleanSet){
if(booleanSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Boolean aBoolean : booleanSet){
objectSet.add(aBoolean);
}
return objectSet;
}
global static Set<Object> dateToObject(Set<Date> dateSet){
if(dateSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Date aDate : dateSet){
objectSet.add(aDate);
}
return objectSet;
}
global static Set<Object> datetimeToObject(Set<Datetime> datetimeSet){
if(datetimeSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Datetime aDatetime : datetimeSet){
objectSet.add(aDatetime);
}
return objectSet;
}
global static Set<Object> decimalToObject(Set<Decimal> decimalSet){
if(decimalSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Decimal aDecimal : decimalSet){
objectSet.add(aDecimal);
}
return objectSet;
}
global static Set<Object> doubleToObject(Set<Double> doubleSet){
if(doubleSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Double aDouble : doubleSet){
objectSet.add(aDouble);
}
return objectSet;
}
global static Set<Object> idToObject(Set<ID> idSet){
if(idSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(ID aID : idSet){
objectSet.add(aID);
}
return objectSet;
}
global static Set<Object> integerToObject(Set<Integer> integerSet){
if(integerSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Integer aInteger : integerSet){
objectSet.add(aInteger);
}
return objectSet;
}
global static Set<Object> longToObject(Set<Long> longSet){
if(longSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Long aLong : longSet){
objectSet.add(aLong);
}
return objectSet;
}
global static Set<Object> timeToObject(Set<Time> timeSet){
if(timeSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(Time aTime : timeSet){
objectSet.add(aTime);
}
return objectSet;
}
global static Set<Object> stringToObject(Set<String> stringSet){
if(stringSet == null){
return null;
}
Set<Object> objectSet = new Set<Object>();
for(String aString : stringSet){
objectSet.add(aString);
}
return objectSet;
}
global static String toString(Set<Blob> blobSet){ return toString(blobToObject(blobSet)); }
global static String toString(Set<Boolean> booleanSet){ return toString(booleanToObject(booleanSet)); }
global static String toString(Set<Date> dateSet){ return toString(dateToObject(dateSet)); }
global static String toString(Set<Datetime> datetimeSet){ return toString(datetimeToObject(datetimeSet)); }
global static String toString(Set<Decimal> decimalSet){ return toString(decimalToObject(decimalSet)); }
global static String toString(Set<Double> doubleSet){ return toString(doubleToObject(doubleSet)); }
global static String toString(Set<ID> idSet){ return toString(idToObject(idSet)); }
global static String toString(Set<Integer> integerSet){ return toString(integerToObject(integerSet)); }
global static String toString(Set<Long> longSet){ return toString(longToObject(longSet)); }
global static String toString(Set<Time> timeSet){ return toString(timeToObject(timeSet)); }
global static String toString(Set<String> stringSet){ return toString(stringToObject(stringSet)); }
global static String toString(Set<Object> objectSet){
if(objectSet == null){
return 'null';
}
if(objectSet.size() <= 0){
return '{}';
}
String returnValue = '';
Boolean isFirst = true;
for(Object anObject : objectSet){
if(isFirst){
isFirst = false;
} else {
returnValue += ',';
}
if(anObject instanceof Blob){ returnValue += '\'' + ((Blob)anObject).toString() + '\'';
} else if(anObject instanceof Boolean){ returnValue += ((Boolean)anObject);
} else if(anObject instanceof Date){ returnValue += '\'' + ((Date)anObject) + '\'';
} else if(anObject instanceof Datetime){ returnValue += '\'' + ((Datetime)anObject) + '\'';
} else if(anObject instanceof Integer){ returnValue += ((Integer)anObject);
} else if(anObject instanceof Long){ returnValue += ((Long)anObject);
} else if(anObject instanceof Decimal){ returnValue += ((Decimal)anObject);
//} else if(anObject instanceof Double){ returnValue += ((Double)anObject);
} else if(anObject instanceof String){ returnValue += '\'' + ((String)anObject) + '\'';
//} else if(anObject instanceof ID){ returnValue += '\'' + ((ID)anObject) + '\'';
} else if(anObject instanceof Time){ returnValue += '\'' + ((Time)anObject) + '\'';}
}
return '{' + returnValue + '}';
}
global static void assertEquals(Set<Blob> b1,Set<Blob> b2){ assertEquals(blobToObject(b1),blobToObject(b2)); }
global static void assertEquals(Set<Boolean> b1,Set<Boolean> b2){ assertEquals(booleanToObject(b1),booleanToObject(b2)); }
global static void assertEquals(Set<Date> d1,Set<Date> d2){ assertEquals(dateToObject(d1),dateToObject(d2)); }
global static void assertEquals(Set<Datetime> d1,Set<Datetime> d2){ assertEquals(datetimeToObject(d1),datetimeToObject(d2)); }
global static void assertEquals(Set<Decimal> d1,Set<Decimal> d2){ assertEquals(decimalToObject(d1),decimalToObject(d2)); }
global static void assertEquals(Set<Double> d1,Set<Double> d2){ assertEquals(doubleToObject(d1),doubleToObject(d2)); }
global static void assertEquals(Set<Integer> i1,Set<Integer> i2){ assertEquals(integerToObject(i1),integerToObject(i2)); }
global static void assertEquals(Set<Long> l1,Set<Long> l2){ assertEquals(longToObject(l1),longToObject(l2)); }
global static void assertEquals(Set<String> s1,Set<String> s2){ assertEquals(stringToObject(s1),stringToObject(s2)); }
global static void assertEquals(Set<Time> t1,Set<Time> t2){ assertEquals(timeToObject(t1),timeToObject(t2)); }
global static void assertEquals(Set<Object> expected, Set<Object> actual){
System.assert(
equals(expected,actual),
'Assertion failed, the following two arrays are not equal. Expected: '
+ toString(expected)
+ ', Actual: '
+ toString(actual));
}
global static Boolean equals(Set<Blob> b1,Set<Blob> b2){ return equals(blobToObject(b1),blobToObject(b2)); }
global static Boolean equals(Set<Boolean> b1,Set<Boolean> b2){ return equals(booleanToObject(b1),booleanToObject(b2)); }
global static Boolean equals(Set<Date> d1,Set<Date> d2){ return equals(dateToObject(d1),dateToObject(d2)); }
global static Boolean equals(Set<Datetime> d1,Set<Datetime> d2){ return equals(datetimeToObject(d1),datetimeToObject(d2)); }
global static Boolean equals(Set<Decimal> d1,Set<Decimal> d2){ return equals(decimalToObject(d1),decimalToObject(d2)); }
global static Boolean equals(Set<Double> d1,Set<Double> d2){ return equals(doubleToObject(d1),doubleToObject(d2)); }
global static Boolean equals(Set<Integer> i1,Set<Integer> i2){ return equals(integerToObject(i1),integerToObject(i2)); }
global static Boolean equals(Set<Long> l1,Set<Long> l2){ return equals(longToObject(l1),longToObject(l2)); }
global static Boolean equals(Set<String> s1,Set<String> s2){ return equals(stringToObject(s1),stringToObject(s2)); }
global static Boolean equals(Set<Time> t1,Set<Time> t2){ return equals(timeToObject(t1),timeToObject(t2)); }
global static Boolean equals(Set<Object> expected, Set<Object> actual){
if(expected == null && actual == null){
return true;
}
if((expected == null && actual != null) || (expected != null && actual == null)){
return false;
}
if(expected.size() != actual.size()){
return false;
}
for(Object obj : expected){
if(!actual.contains(obj)){
return false;
}
}
return true;
}
global static Set<Object> pluck(List<SObject> records, String fieldName){
return pluck(listToSet(records),fieldName);
}
global static Set<Object> pluck(Set<SObject> records, String fieldName){
Set<Object> returnValue = null;
if(records != null){
returnValue = new Set<Object>();
if(records.size() > 0 && StringUtils.isNotBlank(fieldName)){
for(SObject record : records){
returnValue.add(record.get(fieldName));
}
}
}
return returnValue;
}
global static Set<String> pluckString(List<SObject> records, String fieldName){
return pluckString(listToSet(records),fieldName);
}
global static Set<String> pluckString(Set<SObject> records, String fieldName){
return objectToString(pluck(records,fieldName));
}
global static List<String> setToList(Set<String> aSet){
List<String> returnValue = null;
if(aSet != null){
returnValue = new List<String>();
if(aSet.size() > 0){
for(String value : aSet){
returnValue.add(value);
}
}
}
return returnValue;
}
global static List<Object> setToList(Set<Object> records){
List<Object> returnValue = null;
if(records != null){
returnValue = new List<Object>();
if(records.size() > 0){
for(Object record : records){
returnValue.add(record);
}
}
}
return returnValue;
}
global static List<SObject> setToList(Set<SObject> records){
List<SObject> returnValue = null;
if(records != null){
returnValue = new List<SObject>();
if(records.size() > 0){
for(SObject record : records){
returnValue.add(record);
}
}
}
return returnValue;
}
global static Set<String> listToSet(List<String> aList){
Set<String> returnValue = null;
if(aList != null){
returnValue = new Set<String>();
if(aList.size() > 0){
for(String value : aList){
returnValue.add(value);
}
}
}
return returnValue;
}
global static Set<Object> listToSet(List<Object> aList){
Set<Object> returnValue = null;
if(aList != null){
returnValue = new Set<Object>();
if(aList.size() > 0){
for(Object value : aList){
returnValue.add(value);
}
}
}
return returnValue;
}
global static Set<SObject> listToSet(List<SObject> records){
Set<SObject> returnValue = null;
if(records != null){
returnValue = new Set<SObject>();
if(records.size() > 0){
for(SObject record : records){
returnValue.add(record);
}
}
}
return returnValue;
}
global static Set<String> lowerCase(Set<String> strs){
Set<String> returnValue = null;
if(strs != null){
returnValue = new Set<String>();
if(strs.size() > 0){
for(String str : strs){
returnValue.add(str == null ? null : str.toLowerCase());
}
}
}
return returnValue;
}
global static Set<String> upperCase(Set<String> strs){
Set<String> returnValue = null;
if(strs != null){
returnValue = new Set<String>();
if(strs.size() > 0){
for(String str : strs){
returnValue.add(str == null ? null : str.toUpperCase());
}
}
}
return returnValue;
}
global static Set<String> trim(Set<String> strs){
Set<String> returnValue = null;
if(strs != null){
returnValue = new Set<String>();
if(strs.size() > 0){
for(String str : strs){
returnValue.add(str == null ? null : str.trim());
}
}
}
return returnValue;
}
}
Set<String> zip_codes = new Set<String>((List<String>) Utils.getValuesByField(...));
. Bottom line is limit your ambitions when using Apex.