Object Wrappers are serializable classes and thus can be safely passed between classes possibly running inside different processes.
A2:
Use the Integer.parseInt( String s ) method.
A3:
Immutability means that an object's value cannot be changed; in order to change the value of an immutable class, a new instance of the class must be created with the new value and the old value is orphaned in memory.
A4:
Because strings are immutable, Java has created the notion of a string table that represents all strings running in an application; this is an optimization so that only one instance of a string is represented in memory even if multiple variables are referencing it.
A5:
Java has created the notion of a string table that represents all strings running in an application; this is an optimization so that only one instance of a string is represented in memory even if multiple variables are referencing it.
A6:
The String class is immutable while the StringBuffer class is not; the StringBuffer class is free to change its value without having to orphan its old value in memory and create a new instance in memory as the String class does.
A7:
The StringBuffer class provides a reverse() method that reverses the contents of a string.
A8:
The StringTokenizer class is a utility class that takes a String and returns tokens, with delimiters defined by the caller, back to the caller.
A9:
A delimiter defines the characters that separate tokens.
A10:
Some of its uses include parsing text based documents into words or parsing comma-separated value (CSV) files into their comma-separated values.