Convert a List to a Set (ArrayList to HashSet)

This example shows how to convert from an ArrayList to a HashSet. Since most Collection objects have a constructor that allows for passing in another Collection object we are able to make these kinds of conversions easily.
In the example we create an ArrayList to which we add a few string items. Next we create a HashSet and provide the reference to the ArrayList as argument to the HashSet constructor.
Finally we just loop through the HashSet and print out the contents.
　
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
*
* @author
*/
public class Main {
/**
* Conversion from a List to a Set,
* or from an ArrayList to a HashSet object
*/
public void convertFromListToSet() {
List fruitsList = new ArrayList ();
fruitsList.add("Apples");
fruitsList.add("Bananas");
fruitsList.add("Oranges");
fruitsList.add("Grapes");
Set fruitsSet = new HashSet(fruitsList);
for (Object theFruit : fruitsSet)
System.out.println(theFruit);
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
new Main().convertFromListToSet();
}
}
The output from the code is not surprisingly the items in the same order as added to the ArrayList:
Apples
Bananas
Oranges
Grapes