Saturday 25 September 2010

Operations on a set

Create the set

Set set = new HashSet();

 
Add elements to the set

set.add("a");
set.add("b");
set.add("c");



Remove elements from the set

set.remove("c"); 


Get number of elements in set

int size = set.size(); // 2


Adding an element that already exists in the set has no effect
 

set.add("a"); 
size = set.size(); // 2


Determining if an element is in the set

boolean b = set.contains("a"); // true
b = set.contains("c"); // false //


Iterating over the elements in the set

Iterator it = set.iterator();
while (it.hasNext()) {
// Get element
Object element = it.next();
}


Create an array containing the elements in the set (in this case a String array)

String[] array = (String[])set.toArray(new String[set.size()]);

 


 

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