LinkedHashMap with ArrayList - How to load ArrayList?

Question

I am fairly new to Java and am trying to load a LinkedHashMap that contains an ArrayList of values. I am trying to load the values from a query result from an API based query result (Salesforce).

Here is the error: "Cannot refer to a non-final variable breakdown inside an inner class defined in a different method" - the breakdown variable is underlined in red giving this message, Ive noted the line in concern below.

CODE

public LinkedHashMap<String, ArrayList<String>> sfFundIdsByContact; public ArrayList<String> getFundsIDsForContact(Contact aContact) { QueryResult queryResults = null; ArrayList<String> ids = new ArrayList<String>(); int index = 0; Boolean done = false; String contactid = aContact.getId(); String SCCPBId = null; if(sfFundIdsByContact == null || sfFundIdsByContact.size() <= 0){ //Do the Salesforce API CALL and Return the results ... while (! done) { SObject[] records = queryResults.getRecords(); for ( int i = 0; i < records.length; ++i ) { if(sfFundIdsByContact.containsKey(breakdown.getSalesConnect__Contact__c())){ sfFundIdsByContact.get(breakdown.getSalesConnect__Contact__c()).add(breakdown.getId()); } else { //Line below in the add(breakdown.getId() - contains the error sfFundIdsByContact.put(breakdown.getSalesConnect__Contact__c(), new ArrayList<String>() {{ add(breakdown.getId()); }}); } }

All suggestions are appreciated.

Sorry guys - you are too quick ;) - I had some trouble getting the code in the "CODE" section, but it should be good now. — user2774325
– user2774325, Commented Oct 21, 2013 at 21:11

Rohit Jain · Accepted Answer · 2013-10-21 21:08:44Z

3

In your else block, instead of:

new ArrayList<String>() {{ add(**breakdown.getId()**); }}

you can use:

new ArrayList<String>(Arrays.asList(breakdown.getId())

or, since you just want a single element ArrayList, you can use Collections.singletonList that avoids the creation of temporary varargs array:

new ArrayList<String>(Collections.singletonList(breakdown.getId())

The { ... } after the new ArrayList<>() creates an anonymous subclass of ArrayList, which is an inner class only. Inside an inner class you cannot access non-final local variables.

edited Oct 21, 2013 at 21:08

answered Oct 21, 2013 at 21:03

Rohit Jain

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19 Comments

Holger Over a year ago

Or new ArrayList<String>(Collections.singletonList(breakdown.getId()). This saves the temporary varargs array.

Luiggi Mendoza Over a year ago

There's no need to use new ArrayList<String>, just use Arrays.asList(breakdown.getId() (assuming that getId() returns a String).

Rohit Jain Over a year ago

@LuiggiMendoza I guess that would also be fine here. But just to give OP an equivalent code without change in behaviour I wrote that. asList returns fixed size list right?

Luiggi Mendoza Over a year ago

In HotSpot, Arrays#asList simply implements this as return new ArrayList<T>(T[] array), so you end creating an ArrayList from another ArrayList.

Holger Over a year ago

@Luiggi Mendoza: Then the map´s type LinkedHashMap<String, ArrayList<String>> must be changed to LinkedHashMap<String, List<String>>

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Community · Accepted Answer · 2017-05-23 10:31:46Z

You can ease the code by always retrieving the List value in the for loop, then if it is null create a new one and add it to your Map, otherwise add the value to the list.

for (int i = 0; i < records.length; i++) { List<String> value = sfFundIdsByContact.get(breakdown.getSalesConnect__Contact__c()); if (value == null) { value = new ArrayList<String>(); sfFundIdsByContact.put(breakdown.getSalesConnect__Contact__c(), value); } value.add(breakdown.getId()); }

As a recommendation, change the definition of

LinkedHashMap<String, ArrayList<String>> sfFundIdsByContact

to

Map<String, List<String>> sfFundIdsByContact

Refer to What does it mean to "program to an interface"?

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