Diamond Operator

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Table of Contents

• Diamond Operator
  • Table of Contents
  • Overview
  • Ref.

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Overview

Before the diamond operator, when creating instances of generic classes, you had to explicitly specify the type parameter twice, once during declaration and once during instantiation:

List<String> myList = new ArrayList<String>(); // Java 6 and earlier

With the diamond operator, the redundant type information can be omitted:

List<String> myList = new ArrayList<>(); // Java 7 and later

The diamond operator works with any generic class, not just ArrayList

Map<String, Integer> myMap = new HashMap<>(); // Java 7 and later
Set<Double> mySet = new HashSet<>(); // Java 7 and later

The Java 1.7 compiler’s type inference feature determines the most suitable constructor declaration that matches the invocation.

• See also: Collections API
• See also: Generics

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Ref.

https://www.baeldung.com/java-diamond-operator

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Get Started | Languages | Java Development | Java 7

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