Wednesday, September 26, 2007

Java Interview Questions-3

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.

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