Question

I am having below error for this code,

Type mismatch: cannot convert from Set<Map.Entry<Date,List<Transaction>>> to Set<Date>

Code:

final Map<Date, List<Transaction>> transactionsMap= new HashMap<Date, List<Transaction>>();

Set<Date> set = transactionsMap.entrySet(); //Error line

What is this error? how to resolve this?

Answer 1

You need to use keySet() to get the set of key values. entrySet() returns the set of entries (i.e. key and value combined).

Map<Date, List<Transaction>> transactionsMap= new HashMap<Date, List<Transaction>>();
Set<Date> set = transactionsMap.keySet();

If, however, you want to use the entrySet() method, then you’ll need to use the appropriate type for your variable:

Set<Map.Entry<Date, List<Transaction>> entries = transactionMap.entrySet();