Frequently Asked Questions - Java

• Can a main() method of class be invoked in another class?



• What is the difference between java command line arguments and C command line arguments?



• What is the difference between == & .equals



• What is the difference between abstract class & Interface.



• What is singleton class & it's implementation.



• Use of static,final variable



• Examples of final class



• Difference between Event propagation & Event delegation



• Difference between Unicast & Multicast model



• What is a java bean



• What is synchronized keyword used for.



• What are the restrictions of an applet & how to make the applet access the local machines resources.



• What is reflect package used for & the methods of it.



• What is serialization used for



• Can methods be overloaded based on the return types ?



• Why do we need a finalze() method when Garbage Collection is there ?



• Difference between AWT and Swing compenents ?



• Is there any heavy weight component in Swings ?



• Can the Swing application if you upload in net, be compatible with your browser?



• What should you do get your browser compatible with swing components?



• What are the methods in Applet ?



• When is init(),start() called ?



• When you navigate from one applet to another what are the methods called?



• What is the difference between Trusted and Untrusted Applet ?



• What is Exception ?



• What are the ways you can handle exception ?



• When is try,catch block used ?



• What is finally method in Exceptions ?



• What are the types of access modifiers ?



• What is protected and friendly ?



• What are the other modifiers ?



• Is synchronised modifier ?



• What is meant by polymorphism ?



• What is inheritance ?



• What is method Overloading ? What is this in OOPS ?



• What is method Overriding ? What is it in OOPS ?



• Does java support multi dimensional arrays ?



• Is multiple inheritance used in Java ?



• How do you send a message to the browser in JavaScript ?



• Does javascript support multidimensional arrays ?



• Is there any tool in java that can create reports ?



• What is meant by Java ?



• What is meant by a class ?



• What is meant by a method ?



• What are the OOPS concepts in Java ?



• What is meant by encapsulation ? Explain with an example



• What is meant by inheritance ? Explain with an example



• What is meant by polymorphism ? Explain with an example



• Is multiple inheritance allowed in Java ? Why ?



• What is meant by Java interpreter ?



• What is meant by JVM ?



• What is a compilation unit ?



• What is meant by identifiers ?



• What are the different types of modifiers ?



• What are the access modifiers in Java ?



• What are the primitive data types in Java ?



• What is meant by a wrapper class ?



• What is meant by static variable and static method ?



• What is meant by Garbage collection ?



• What is meant by abstract class



• What is meant by final class, methods and variables ?



• What is meant by interface ?



• What is meant by a resource leak ?



• What is the difference between interface and abstract class ?



• What is the difference between public private, protected and static



• What is meant by method overloading ?



• What is meant by method overriding ?



• What is singleton class ?



• What is the difference between an array and a vector ?



• What is meant by constructor ?



• What is meant by casting ?



• What is the difference between final, finally and finalize ?



• What is meant by packages ?



• What are all the packages ?



• Name 2 calsses you have used ?



• Name 2 classes that can store arbitrary number of objects ?



• What is the difference between java.applet.* and java.applet.Applet ?



• What is a default package ?



• What is meant by a super class and how can you call a super class ?



• What is anonymous class ?



• Name interfaces without a method ?



• What is the use of an interface ?



• What is a serializable interface ?



• How to prevent field from serialization ?



• What is meant by exception ?



• How can you avoid the runtime exception ?



• What is the difference between throw and throws ?



• What is the use of finally ?



• Can multiple catch statements be used in exceptions ?



• Is it possible to write a try within a try statement ?



• What is the method to find if the object exited or not ?



• What is meant by a Thread ?



• What is meant by multi-threading ?



• What is the 2 way of creating a thread ? Which is the best way and why?



• What is the method to find if a thread is active or not ?



• What are the thread-to-thread communcation ?



• What is the difference between sleep and suspend ?



• Can thread become a member of another thread ?



• What is meant by deadlock ?



• How can you avoid a deadlock ?



• What are the three typs of priority ?



• What is the use of synchronizations ?



• Garbage collector thread belongs to which priority ?



• What is meant by time-slicing ?



• What is the use of 'this' ?



• How can you find the length and capacity of a string buffer ?



• How to compare two strings ?



• What are the interfaces defined by Java.lang ?



• What is the purpose of run-time class and system class



• What is meant by Stream and Types ?



• What is the method used to clear the buffer ?



• What is meant by Stream Tokenizer ?



• What is serialization and de-serialisation ?



• What is meant by Applet ?



• How to find the host from which the Applet has originated ?



• What is the life cycle of an Applet ?



• How do you load an HTML page from an Applet ?



• What is meant by Applet Stub Interface ?



• What is meant by getCodeBase and getDocumentBase method ?



• How can you call an applet from a HTML file



• What is meant by Applet Flickering ?



• What is the use of parameter tag ?



• What is audio clip Interface and what are all the methods in it ?



• What is the difference between getAppletInfo and getParameterInfo ?



• How to communicate between applet and an applet ?



• What is meant by event handling ?



• What are all the listeners in java and explain ?



• What is meant by an adapter class ?



• What are the types of mouse event listeners ?



• What are the types of methods in mouse listeners ?



• What is the difference between panel and frame ?



• What is the default layout of the panel and frame ?



• What is meant by controls and types ?



• What is the difference between a scroll bar and a scroll panel.



• What is the difference between list and choice ?



• How to place a component on Windows ?



• What are the different types of Layouts ?



• What is meant by CardLayout ?



• What is the difference between GridLayout and GridBagLayout



• What is the difference between menuitem and checkboxmenu item.



• What is meant by vector class, dictionary class , hash table class,and property class ?



• Which class has no duplicate elements ?



• What is resource bundle ?



• What is an enumeration class ?



• What is meant by Swing ?



• What is the difference between AWT and Swing ?



• What is the difference between an applet and a Japplet



• What are all the components used in Swing ?



• What is meant by tab pans ?



• What is the use of JTree ?



• How can you add and remove nodes in Jtree.



• What is the method to expand and collapse nodes in a Jtree



• What is the use of JTable ?



• What is meant by JFC ?



• What is the class in Swing to change the appearance of the Frame in Runtime.



• How to reduce flicking in animation ?



• What is meant by Javabeans ?



• What is JAR file ?



• What is meant by manifest files ?



• What is Introspection ?



• What are the steps involved to create a bean ?



• Say any two properties in Beans ?



• What is persistence ?



• What is the use of beaninfo ?



• What are the interfaces you used in Beans ?



• What are the classes you used in Beans ?



• What is the diffrence between an Abstract class and Interface



• What is user defined exception ?



• What do you know about the garbate collector ?



• What is the difference between C++ & Java ?



• How do you communicate in between Applets & Servlets ?



• What is the use of Servlets ?



• In an HTML form I have a Button which makes us to open another page in 15 seconds. How will do you that ?



• What is the difference between Process and Threads ?



• How will you initialize an Applet ?



• What is the order of method invocation in an Applet ?



• When is update method called ?



• How will you communicate between two Applets ?



• Have you ever used HashTable and Dictionary ?



• What are statements in JAVA ?



• What is JAR file ?



• What is JNI ?



• What is the base class for all swing components ?



• What is JFC ?



• What is Difference between AWT and Swing ?



• Considering notepad/IE or any other thing as process, What will Happen if you start notepad or IE 3 times? Where 3 processes are started or 3 threads are started ?



• How does thread synchronization occurs inside a monitor ?



• How will you call an Applet using a Java Script function ?



• Is there any tag in HTML to upload and download files ?



• Why do you Canvas ?



• How can you push data from an Applet to Servlet ?



• What are the benefits of Swing over AWT ?



• Where the CardLayout is used ?



• What is the Layout for ToolBar ?



• What is the difference between Grid and GridbagLayout ?



• How will you add panel to a Frame ?



• What is the corresponding Layout for Card in Swing ?



• What is light weight component ?



• What is bean ? Where it can be used ?



• What is difference in between Java Class and Bean ?



• What is the mapping mechanism used by Java to identify IDL language ?



• Diff between Application and Applet ?



• What is serializable Interface ?



• What is the difference between CGI and Servlet ?



• What is the use of Interface ?



• Why Java is not fully objective oriented ?



• Why does not support multiple Inheritance ?



• What it the root class for all Java classes ?



• What is polymorphism ?



• Suppose If we have variable ' I ' in run method, If I can create one or More thread each thread will occupy a separate copy or same variable will be shared ?



• What is Constructor and Virtual function? Can we call Virtual



• Funciton in a constructor ?



• Why we use OOPS concepts? What is its advantage ?



• What is the difference in between C++ and Java ? can u explain in detail?



• What is the exact difference in between Unicast and Multicast object ? Where we will use ?



• How do you sing an Applet ?



• In a Container there are 5 components. I want to display the all the components names, how will you do that one ?



• Why there are some null interface in java ? What does it mean ?



• Give me some null interfaces in JAVA ?



• Tell me the latest versions in JAVA related areas ?



• What is meant by class loader ? How many types are there? When will we use them ?



• What is meant by flickering ?



• What is meant by cookies ? Explain ?



• Problem faced in your earlier project



• How OOPS concept is achieved in Java



• Features for using Java



• How does Java 2.0 differ from Java 1.0



• Public static void main - Explain



• What are command line arguments



• Explain about the three-tier model



• Difference between String & StringBuffer



• Wrapper class. Is String a Wrapper Class



• What are the restriction for static method Purpose of the file class



• Default modifier in Interface



• Difference between Interface & Abstract class



• Can abstract be declared as Final



• Can we declare variables inside a method as Final Variables



• What is the package concept and use of package



• How can a dead thread be started



• Difference between Applet & Application



• Life cycle of the Applet



• Can Applet have constructors



• Differeence between canvas class & graphics class



• Explain about Superclass & subclass



• What is AppletStub



• Explain Stream Tokenizer



• What is the difference between two types of threads



• Checked & Unchecked exception



• Use of throws exception



• What is finally in exception handling Vector class



• What will happen to the Exception object after exception handling



• Two types of multi-tasking



• Two ways to create the thread



• Synchronization



• I/O Filter



• Can applet in different page communicate with each other



• Why Java is not 100 % pure OOPS ? ( EcomServer )



• When we will use an Interface and Abstract class ?



• How to communicate 2 threads each other ?