The transient keyword is used to indicate to the JVM that the indicated variable is not part of the persistent state of the object. All the Variables which are part of the persistent state of an object are required to be saved when the object is archived. At that time, the transient marker is ignored by the Java runtime system.
Keyword - this
A keyword is a word having a particular meaning to the programming language. Similarly, this keyword is used to represent an object constructed from a class in which it appears.
This is an abstract adapter class used to receive keyboard events. This is the class is used to receive the keyboard events. It creates the keyListener objects using the addKeyListener() method.
Recommend the tutorial