Jack developed a program by using a Map container to hold key/value pairs. He wanted to make a change to the map. He decided to make a clone of the map in order to save the original data on side. What do you think of it? ?

Java Interview Questions and Answers (part 1)

(Continued from previous question...)

3. Jack developed a program by using a Map container to hold key/value pairs. He wanted to make a change to the map. He decided to make a clone of the map in order to save the original data on side. What do you think of it? ?

If Jack made a clone of the map, any changes to the clone or the original map would be seen on both maps, because the clone of Map is a shallow copy. So Jack made a wrong decision.

(Continued on next question...)

Other Interview Questions

• What's Java?
• What does a well-written OO program look like?
• Can you have virtual functions in Java?
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• What is more advisable to create a thread, by implementing a Runnable interface or by extending Thread class?
• What is NullPointerException and how to handle it?
• An application needs to load a library before it starts to run, how to code??
• How could Java classes direct program messages to the system console, but error messages, say to a file?
• What's the difference between an interface and an abstract class?
• Name the containers which uses Border Layout as their default layout?
• What do you understand by Synchronization?
• What is Collection API?
• Is Iterator a Class or Interface? What is its use?
• What is similarities/difference between an Abstract class and Interface?
• How to define an Abstract class?
• How to define an Interface?
• If a class is located in a package, what do you need to change in the OS environment to be able to use it?
• How many methods in the Serializable interface?
• How many methods in the Externalizable interface?
• What is the difference between Serializalble and Externalizable interface?
• What is a transient variable?
• Which containers use a border layout as their default layout?
• How are Observer and Observable used?
• What is synchronization and why is it important?
• What are synchronized methods and synchronized statements?
• What are three ways in which a thread can enter the waiting state?
• Can a lock be acquired on a class?
• What's new with the stop(), suspend() and resume() methods in JDK 1.2?
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• What would you use to compare two String variables - the operator == or the method equals()?
• What is thread?
• What is multi-threading?
• How does multi-threading take place on a computer with a single CPU?
• How to create a thread in a program?
• Can Java object be locked down for exclusive use by a given thread?
• Can each Java object keep track of all the threads that want to exclusively access to it?
• Does it matter in what order catch statements for FileNotFoundException and IOExceptipon are written?
• What invokes a thread's run() method?
• What is the purpose of the wait(), notify(), and notifyAll() methods?
• What are the high-level thread states?
• What is the difference between yielding and sleeping?
• What happens when a thread cannot acquire a lock on an object?
• What is the difference between Process and Thread?
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• What is the Vector class?
• What modifiers may be used with an inner class that is a member of an outer class?
• If a method is declared as protected, where may the method be accessed?
• What is an Iterator interface?
• How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
• What's the main difference between a Vector and an ArrayList?
• What are wrapped classes?
• Does garbage collection guarantee that a program will not run out of memory?
• What is the difference between preemptive scheduling and time slicing?
• Name Component subclasses that support painting?
• What is a native method?
• How can you write a loop indefinitely?
• Can an anonymous class be declared as implementing an interface and extending a class?
• What is the purpose of finalization?
• When should the method invokeLater()be used?
• How many methods in Object class?
• How does Java handle integer overflows and underflows?
• What is the numeric promotion?
• Is the numeric promotion available in other plantform?
• What is the difference between the Boolean & operator and the && operator?
• When is the ArithmeticException throwQuestion: What is the GregorianCalendar class?
• What is the SimpleTimeZone class?
• How can a subclass call a method or a constructor defined in a superclass?
• What is the Properties class?
• What is the purpose of the Runtime class?
• What is the purpose of the System class?
• What is the purpose of the finally clause of a try-catch-finally statement?
• What is the Locale class?
• What is an abstract method?
• What is the difference between interface and abstract class?
• What is a static method?
• What is a protected method?
• What is the difference between a static and a non-static inner class?
• What is an object's lock and which object's have locks?
• When can an object reference be cast to an interface reference?
• What is the difference between a Window and a Frame?
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• Which package has light weight components?
• What are peerless components?
• What is the difference between the Font and FontMetrics classes?
• What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?
• What classes of exceptions may be caught by a catch clause?
• What is the difference between throw and throws keywords?
• If a class is declared without any access modifiers, where may the class be accessed?
• What is the Map interface?
• Does a class inherit the constructors of its superclass?
• Name primitive Java types.
• Which class should you use to obtain design information about an object?
• How can a GUI component handle its own events?
• How are the elements of a GridBagLayout organized?
• What advantage do Java's layout managers provide over traditional windowing systems?
• What are the problems faced by Java programmers who don't use layout managers?
• What is the difference between static and non-static variables?
• What is the difference between the paint() and repaint() methods?
• What is the purpose of the File class?
• Why would you use a synchronized block vs. synchronized method?
• What restrictions are placed on method overriding?
• What is casting?
• Explain the usage of the keyword transient?
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• How are this() and super() used with constructors?
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• What is an IO filter?
• What is the Set interface?
• How can you force garbage collection?
• What is the purpose of the enableEvents() method?
• What is the difference between the File and RandomAccessFile classes?
• What interface must an object implement before it can be written to a stream as an object?
• What is the ResourceBundle class?
• How do you know if an explicit object casting is needed?
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• What are the Object and Class classes used for?
• What is Serialization and deserialization?
• Explain the usage of Java packages.
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• What is polymorphism?
• What is design by contract?
• What are use cases?
• What is scalability and performance?
• What is the benefit of subclass?
• How to add menushortcut to menu item?
• Where and how can you use a private constuctor.
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• Can one create a method which gets a String and modifies it?
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