Java Interview Questions - Page 4
Question: What are synchronized methods and synchronized statements?
Answer:
Synchronized methods are methods that are used to control access to an
object. A thread only executes a synchronized method after it has acquired
the lock for the method's object or class. Synchronized statements are
similar to synchronized methods. A synchronized statement can only be
executed after a thread has acquired the lock for the object or class
referenced in the synchronized statement.
Question: What are three ways in which a thread can enter the waiting state?
Answer: A
thread can enter the waiting state by invoking its sleep() method, by
blocking on I/O, by unsuccessfully attempting to acquire an object's lock,
or by invoking an object's wait() method. It can also enter the waiting
state by invoking its (deprecated) suspend() method.
Question: Can a lock be acquired on a class?
Answer: Yes, a lock can be acquired on a
class. This lock is acquired on the class's Class object.
Question: What's new with the stop(), suspend() and resume() methods in JDK
1.2?
Answer: The stop(), suspend() and resume() methods have been deprecated in JDK
1.2.
Question: What is the preferred size of a component?
Answer: The preferred size of a
component is the minimum component size that will allow the component to
display normally.
Question: What method is used to specify a container's layout?
Answer: The setLayout()
method is used to specify a container's layout.
Question: Which containers use a FlowLayout as their default layout?
Answer: The Panel
and Applet classes use the FlowLayout as their default layout.
Question: What is thread?
Answer: A thread is an independent path of execution in a
system.
Question: What is multithreading?
Answer: Multithreading means various threads that run
in a system.
Question: How does multithreading take place on a computer with a single CPU?
Answer:
The operating system's task scheduler allocates execution time to multiple
tasks. By quickly switching between executing tasks, it creates the
impression that tasks execute sequentially.