Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Hello I tried to create a TreeMap in Java but the compiler gives the error saying “unexpected type”.
Can anyone tell me why? Isn’t possible to have primitive data types in a Map?
I did solve it by using the java.lang.Boolean instead. But I don’t understand why I can’t mix a complex data type with a primitive one.
To answer your query,
Maps and other classes which are treated as collections not only serve the purpose of storing data but they also provide methods for comparing. In java comparators are used for the same. In short you need to call methods on the objects you want to compare. If the values are primitive data type, no methods can be invoked on them. This is precisely one of the major reasons why primitive data types are not permitted in collections and related classes.
hope this helps