Home/ Questions/Q 7401335
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-29T04:26:15+00:00

I am new to Android. Basically done programming in C++. There is a small

  • 0

I am new to Android. Basically done programming in C++. There is a small notation I don’t understand. Can Anybody help me with this?

Ex: HashMap<String, String> o = (HashMap<String, String>)

My question is what is the use of < and > signs. Sometimes there is one parameter, sometimes there are more, and some look like a data structure.

Ex: ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();

Why there are two parameters inside?

sometimes I saw it with a question mark: AdapterView<?>.

For what purpose you use the < and > sign?

This confuse me more than anything else.

Thank you in advance

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    These are Java generics..

    HashMap<String, String> o = (HashMap<String, String>)objectToBeTypecast

    It specifies that this is not
    just an arbitrary HashMap, but a HashMap with Key and its value as a String parameters, written HashMap < String, String>.
    We say that HashMap is
    a generic interface that takes a type parameters – in this case, String.

    To know more about generics, you can have a look here

    • 0