T- the type to set and get
public interface Mutable
Note: it's copied from Apache Commons Lang developed at The Apache Software Foundation (http://www.apache.org/), or under the Apache License 2.0. The methods copied from other products/frameworks may be modified in this class.Provides mutable access to a value.
Mutable is used as a generic interface to the implementations in this package.
A typical use case would be to enable a primitive or string to be passed to a method and allow that method to effectively change the value of the primitive/string. Another use case is to store a frequently changing primitive in a collection (for example a total in a map) without needing to create new Integer/Long wrapper objects.