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Thread: new Vs composition

  1. #1
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    Default new Vs composition

    i wants to ask about the difference between the use of the "new" kewword:
    EX:
    Student s=new Student();

    and the composition, for example:
    public class Proffessor{
    Student advisee;     //an attribute
    //details omitted


  2. #2
    Super Moderator Json's Avatar
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    Default Re: new Vs composition

    The keyword "new" actually tells the JVM to allocate memory and instantiate a new object. This object can then be used through your variable.

    When you dont call new and just create a variable the JVM automatically assigns the value of null to that variable unless its a primitive. This means you have a variable to play with but if you try to invoke any methods on that variable without having a proper object assigned to it you will get a NullPointerException.

    // Json

  3. #3
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    Default Re: new Vs composition

    thanks alot