NavigableSet headSet() method in Java

The headSet() method of

is used to return a view of the portion of this set whose elements are less than (or equal to, if inclusive is true) toElement.

• The returned set is backed by this set, so changes in the returned set are reflected in this set, and vice-versa.
• The returned set supports all optional set operations that this set supports.

Note

: The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.

Syntax

:

NavigableSet<E> headSet(E toElement,
 boolean inclusive)

Where, E is the type of elements maintained by this Set container.

Parameters

: This function has two parameters :

• toElement - high endpoint of the returned set
• inclusive - true if the high endpoint is to be included in the returned view

Return Value

: It return a view of the portion of this set whose elements are less than (or equal to, if inclusive is true) toElement. Below programs illustrate the headSet() method in Java:

Program 1

: NavigableSet with integer elements.

Map with key-value less than given argument : [0, 1, 2, 3, 4, 5]
Map with key-value less than or equal to given argument : [0, 1, 2, 3, 4, 5, 6]

Program 2:

NavigableSet with string elements.

Map with key-value less than given argument : [A, B, C, D, E]
Map with key-value less than or equal to given argument : [A, B, C, D, E]

Reference

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