Storing Primitive Types in a Collection

Collections can only store objects, not primitive types like int and double. Primitive types must be placed in a wrapper object before they can be placed in a collection. This example demonstrates the storing of int values in a Map.

See also: Wrapping a Primitive Type in a Wrapper Object.

// Create map Map map = new HashMap(); // Create int wrapper object Integer refInt = new Integer(123); // Store int in map map.put("key", refInt); // Get int value from map refInt = (Integer)map.get("key"); // Get the integer value from wrapper object int i = refInt.intValue();

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