Advanced Java Questions and Answer for Interview

141. What are the legal operands of the instance of operator?
The left operand is an object reference or null value and the right operand is a class, interface, or array type.

142. How are the elements of a GridBagLayout organized?
The elements of a cGridBagLayout are of equal size and are laid out using the squares of a grid.

143. What an I/O filter?
An I/O filter is an object that reads from one stream and writes to another, usually altering the data in some way as it is passed from one stream to another.

144. If an object is garbage collected, can it become reachable again?
Once an object is garbage collected, it ceases to exist. It can no longer become reachable again.

145. What is the Set interface?
The Set interface provides methods for accessing the elements of a finite mathematical set. Sets do not allow duplicate elements.

146. What classes of exceptions may be thrown by a throw statement?
A throw statement may throw any expression that may be assigned to the Throwable type.

147. What are E and PI?
E is the base of the natural logarithm and PI is mathematical value pi.

148. Are true and false keywords?
The values true and false are not keywords.

149. What is a void return type?
A void return type indicates that a method does not return a value.

150. What is the purpose of the enableEvents() method?
The enableEvents() method is used to enable an event for a particular object. Normally, an event is enabled when a listener is added to an object for a particular event.
The enableEvents() method is used by objects that handle events by overriding their event-dispatch methods.