java.lang.Appendable - An object to which char sequences and values can be appended.
java.lang.CharSequence - A CharSequence is a readable sequence of char values.
java.lang.Readable - A Readable is a source of characters.
java.util.ArrayDeque<E> - Resizable-array implementation of the Deque interface.
java.util.AbstractSet<E> - This class provides a skeletal implementation of the Set interface to minimize the effort required to implement this interface.
Métodos da java.lang.Appendable:
Appendable append(char c) - Appends the specified character to this Appendable.
Appendable append(CharSequence csq) - Appends the specified character sequence to this Appendable.
Appendable append(CharSequence csq, int start, int end) - Appends a subsequence of the specified character sequence to this Appendable.
Fonte: http://download.oracle.com/javase/6/docs/api/