Wrapper classes provide a way to use primitive data types (int, boolean, etc..) as objects.
The table below shows the primitive type and the equivalent wrapper class:
| Primitive Data Type | Wrapper Class |
|---|---|
| byte | Byte |
| short | Short |
| int | Integer |
| long | Long |
| float | Float |
| double | Double |
| boolean | Boolean |
| char | Character |
Sometimes you must use wrapper classes, for example when working with Collection objects, such as ArrayList, where primitive types cannot be used (the list can only store objects):
Example
ArrayList<int> myNumbers = new ArrayList<int>(); // Invalid
ArrayList<Integer> myNumbers = new ArrayList<Integer>(); // Valid
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