Java HashSet add() Method
Example
Add items to a HashSet:
import java.util.HashSet;
public class Main {
public static void main(String[] args) {
HashSet<String> cars = new HashSet<String>();
cars.add("Volvo");
cars.add("BMW");
cars.add("Ford");
cars.add("Mazda");
System.out.println(cars);
}
}Definition and Usage
The add() method adds an item to the set, if the item is not already in the set.
A set cannot contain duplicates. If the item is already in the set, it is not added again, and the method returns false.
Note: A HashSet has no order, so the items are not printed in the order they were added.
Syntax
public boolean add(T item)T refers to the data type of items in the set.
Parameter Values
| Parameter | Description |
|---|---|
| item | Required. The item to add to the set. |
Technical Details
| Returns: | true if the item was added, and false if it was already in the set. |
|---|
More Examples
Example
Check if an item was added:
import java.util.HashSet;
public class Main {
public static void main(String[] args) {
HashSet<String> cars = new HashSet<String>();
cars.add("Volvo");
System.out.println(cars.add("BMW"));
System.out.println(cars.add("Volvo"));
}
}
