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Java

Brendan Whiting
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Brendan Whiting
Front End Web Development Techdegree Graduate 84,735 Points
Posted by Brendan Whiting
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Brendan Whiting
Front End Web Development Techdegree Graduate 84,735 Points

Help understanding why we create an instance with an interface this way

I'm seeing this kind of pattern a few times in the Java courses:

Map<String,String> myMap = new HashMap<String, String>();

Why do we call it Map on the left and HashMap on the right? Why the difference?

Thx

2 Answers

Daniel Vigil
Daniel Vigil
26,473 Points
Daniel Vigil
Daniel Vigil
26,473 Points

There are two sides to the equation. On the left you are referencing the Map interface and on the right you are declaring the concrete child classes of Map. It does open your code to more flexibility in the declaration throughout your code.