java.util.HashSet size()
Description
The HashSet as majority of the Collection classes make use of Generics such that if we have declared our set like HashSet set = new HashSet() then the elements of inside our set is of type String. And we cannot insert different object type not unless its a subclass of the object declaration, otherwise a runtime error will be thrown.
The HashSet elements are unique, there would be no two identical elements that can exist.
Important notes for size() method:
- specified by size in interface Collection
- size in interface Set
- size in class AbstractCollection
Method Syntax
public int size()
Method Argument
| Data Type | Parameter | Description |
|---|---|---|
| N/A | N/A | N/A |
Method Returns
The size() method returns the number of elements in this set (its cardinality).
Compatibility
Requires Java 1.2 and up
Java HashSet size() Example
Below is a java code demonstrates the use of size() method of HashSet class. The example presented might be simple however it shows the behavior of the szie() method.
package com.javatutorialhq.java.examples;
import static java.lang.System.*;
import java.util.HashSet;
/*
* This example source code demonstrates the use of
* size() method of HashSet class
*/
public class HashSetSizeExample {
public static void main(String[] args) throws InterruptedException {
// get the HashMap object from the method init()
HashSet studentSet = init();
// get and print the size of the set
int size = studentSet.size();
out.println("Size of student database is "+size);
}
private static HashSet init() {
// declare the HashSet object
HashSet studentSet = new HashSet<>();
// put contents to our HashMap
studentSet.add("Shyra Travis");
studentSet.add("Sharon Wallace");
studentSet.add("Leo Batista");
studentSet.add("Shyra Travis");
return studentSet;
}
}
There are two methods created on the above example, main() and init. The main method calls the init() which initializes and assign values to a HashSet object. The main() method assign to a new HashSet object the returned object by the init() method. We then print the size of the set.
Sample Output
Below is the sample output when you run the above example.
