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Java - add ArrayList into HashSet
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In this article, we would like to show you how to add ArrayList into HashSet in Java.
In this example, we add existing letters ArrayList to a new alphabet HashSet in the constructor.
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import java.util.*;2
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public class Example {4
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public static void main(String[] args) {6
List<String> letters = new ArrayList<>();7
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letters.add("A");9
letters.add("B");10
letters.add("C");11
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Set<String> alphabet = new HashSet<>(letters);13
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System.out.println(alphabet);15
}16
}Output:
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[A, B, C]In this example, we add existing letters ArrayList to the existing alphabet HashSet using addAll() method.
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import java.util.*;2
3
public class Example {4
5
public static void main(String[] args) {6
Set<String> alphabet = new HashSet<>();7
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alphabet.add("A");9
alphabet.add("B");10
alphabet.add("C");11
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List<String> letters = new ArrayList<>();13
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letters.add("D");15
letters.add("E");16
letters.add("F");17
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alphabet.addAll(letters);19
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System.out.println(alphabet);21
}22
}Output:
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[A, B, C, D, E, F]