Answered Questions

  • Jun 29 2009
    11:05 AM
    6371
    18

    Marker Interface
    • Kamleshnit07

    When there is no methods in the marker interface, then what is the use of marker interface. What is the functionality of the interface. Why do we need to implement marker interface?

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    Saroj_mi2  

    • Member Since Sep-2009 | Sep 14th, 2009

    Marker interface is an interface with out having any implementation methods.
    By implementing this interfaces, we will specify some special behaviour to implemented class.

    Examples: Serializable, Cloneable
    For example if we want to create a clone for a an object of class using clone()(clone()-- which is an object class method), then class need to implement Cloneable interface.

     This mark is to JVM to handle the interface.If you are implimenting this interface the compliler will know some specific job need to be done.
    For Cloneable interface even it does not have any methode the JVM looks for clone() method to execute.     But the complier will not fail if the clone() meth is not implimented.

    uncer

    • Jan 15th, 2010

    When you need to perform some behavioral function on any class without implementing method in implemented interface we implement an interface such interface called marker interface for exmple serializabe, cloneable.

  • Dec 08 2008
    06:47 PM
    8704
    33

    Object Creation
    • justjiten

    In how many ways we can create an object? Explain with example.

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    vishrutha  

    • Member Since Feb-2009 | Feb 13th, 2009

    1. Using new keyword
    This is the most common way to create an object in java. I read somewhere that almost 99% of objects are created in this way.

    MyObject object = new MyObject();

    2. Using Class.forName()
    If we know the name of the class & if it has a public default constructor we can create an object in this way.

    MyObject object = (MyObject) Class.forName("subin.rnd.MyObject").newInstance();

    3. Using clone()
    The clone() can be used to create a copy of an existing object.

    MyObject anotherObject = new MyObject();
    MyObject object = anotherObject.clone();

    4. Using object deserialization
    Object deserialization is nothing but creating an object from its serialized form.

    ObjectInputStream inStream = new ObjectInputStream(anInputStream );
    MyObject object = (MyObject) inStream.readObject();

    5. Using class loader
    one more is through creation of object using classloader like

    this.getClass().getClassLoader().loadClass(”com.amar.myobject”).newInstance();

    Now you know how to create an object. But its advised to create objects only when it is necessary to do so.

    Max

    • Sep 7th, 2011

    All sorts of syntax sugar can also be named: 6. New String as a result of concatenation: String varName = getClass().getName(); //to avoid compile-time optimization String a = "Prefix" + varName; ...