Skip to main content

36 to 40 Java questions

36. What is the difference between yielding and sleeping?
When a task invokes its yield() method, it returns to the ready state. When a task invokes its sleep() method, it returns to the waiting state.

37. What is the difference between preemptive scheduling and time slicing?
Under preemptive scheduling, the highest priority task executes until it enters the waiting or dead states or a higher priority task comes into existence. Under time slicing, a task executes for a predefined slice of time and then reenters the pool of ready tasks. The scheduler then determines which task should execute next, based on priority and other factors.

38. What is mutable object and immutable object?
If a object value is changeable then we can call it as Mutable object. (Ex., StringBuffer, …) If you are not allowed to change the value of an object, it is immutable object. (Ex., String, Integer, Float, …)

39. What is the purpose of Void class?
The Void class is an uninstantiable placeholder class to hold a reference to the Class object representing the primitive Java type void.

40. What is JIT and its use?
Really, just a very fast compiler… In this incarnation, pretty much a one-pass compiler — no offline computations. So you can’t look at the whole method, rank the expressions according to which ones are re-used the most, and then generate code. In theory terms, it’s an on-line problem.

Comments

Post a Comment

Popular posts from this blog

What is Servet ?

A servlet is a java class that extends an application hosted on a web server. Handles the HTTP request-response process (for our purposes) Often thought of as an applet that runs on a server. Provides a component base architecture for web development, using the Java Platform The foundation for Java Server Pages (JSP). Alternative to CGI scripting and platform specific server side applications.
Post a Comment
Read more

Compact Strings -  Java 9 Feature

Motivation The current implementation of the String class stores characters in a char array, using two bytes (sixteen bits) for each character. Data gathered from many different applications indicates that strings are a major component of heap usage and, moreover, that most String objects contain only Latin-1 characters. Such characters require only one byte of storage, hence half of the space in the internal char arrays of such String objects is going unused Description We propose to change the internal representation of the String class from a UTF-16 char array to a byte array plus an encoding-flag field. The new String class will store characters encoded either as ISO-8859-1/Latin-1 (one byte per character), or as UTF-16 (two bytes per character), based upon the contents of the string. The encoding flag will indicate which encoding is used. String-related classes such as AbstractStringBuilder, StringBuilder, and StringBuffer will be updated to use the same representation, as wi...
Post a Comment
Read more

What is Applet ?

***What is an Applet? An Applet is a program that can be referenced by an HTML source code of a web page. It is dynamically downloaded from a web server to a browser and it is executed in the environment provided by the browser. Applet Viewer can also be used to execute  the applet. ***FirstApplet.java import java.applet.Applet; import java.awt.Graphics; /*<applet code=“FirstApplet” width=200 height=200> </applet>*/ public class FirstApplet extends Applet { public void paint(Graphics g) { g.drawString(“Hello World”,20,100); } } *** In the above example, The first two line is importing the java.applet and java.awt.Graphics package. The third line is the comment entry which is used only for applet viewer to execute the applet using the HTML source code. The next line declares the FirstApplet class which extends Applet class. Note that each applet created by user must extend the Applet class. There is a paint() method defined...
Post a Comment
Read more