Week 9 - Wrapper Classes

Each primitive type corresponds to a wrapper class.

• Integer
• Character
• Double
• Boolean

These classes also contain static methods, some of which you've seen:

• int Integer.parseInt (String ...);
• boolean Character.isUpperCase (char ...);
• Double Double.valueOf (String ...);

They also contain non-static methods that can be used to access the value that you've stored in the wrapper class.
Here is an example for the Double wrapper class:

double d = 25.5
Double dWrap = new Double (d);
double d2 = dWrap.doubleValue();

Now we can better understand how String input is converted to a double:

double d = Double.valueOf(in.readLine()).doubleValue();