Wrapper Classes

Wrapper Classes

1. **ALL PRIMITIVES HAVE A WRAPPER CLASS**

2. Wrapper classes do not have no-args constructors.

3. Constructing a wrapper class:

   • Ex: Interger i1 = new Integer("5")
     • Also: Integer i1 = new Integer(5)

4. Ops/Methods:

   • datatypeValue() ex: intValue: turns whatever its called on into an int
     • valueOf(String s): creates a new object initialized to the value represented in the string.
       • compareTo(value): compares two Wrapper classes together returns 1 if >, -1 if <. & 0 if =
         • parseInt(String s) or parseDouble(String s): returns the int or double value of the inputted String. Call it like this: Integer.parseInt("12")

5. Autoboxing: going from a primitive data type to a Wrapper Object.

   • Ex: Integer int1; int val = 12; int1 = val;

6. Unboxing: going from a primitive data type to a Wrapper object.

   • Integer int2 = new Integer(14); int val2; val2 = int2