Static Variables in Java
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Questions and Answers

What happens when a class is loaded into memory?

  • No object is created until it's explicitly called
  • A static object is created immediately (correct)
  • An ordinary object is created immediately
  • A dynamic object is created immediately

    • How are static variables different from non-static variables?

  • Static variables have a single instance while non-static variables have multiple instances (correct)
  • Static variables are bound to specific objects while non-static variables are not
  • Static variables are created only when needed while non-static variables are always created
  • Static variables are not accessible inside the class while non-static variables are accessible

    • What is the default value for an uninitialized static variable of type double?

  • 0
  • 1.0
  • 0.0
  • -1

    • Which keyword do you use to declare a static variable in a class?

    <p>static</p> Signup and view all the answers

    How can you refer to a class's static variables inside the class?

    <p>By using their names directly</p> Signup and view all the answers

    What is the key difference between ordinary variables and static variables in Java?

    <p>Ordinary variables are bound to objects of the class, while static variables are bound to the class's static object.</p> Signup and view all the answers

    In Java, how can you access a static variable defined in a class from another class?

    <p>By using the class name followed by the static variable name</p> Signup and view all the answers

    What happens to static variables when the Java machine finishes loading a class?

    <p>They are stored in the static object of the class</p> Signup and view all the answers

    What is the memory organization difference between static and non-static variables immediately after loading a class in Java?

    <p>Static variables have their own memory space, while non-static variables share memory space with instances of the class</p> Signup and view all the answers

    What is a characteristic of accessing ordinary (non-static) variables in Java?

    <p>They can only be accessed using an object reference to an instance of the class</p> Signup and view all the answers

    What happens when a class is loaded into memory in Java?

    <p>A static object is created immediately and stores static class variables</p> Signup and view all the answers

    What is the default value for an uninitialized static variable of type boolean in Java?

    <p>false</p> Signup and view all the answers

    How can you access a static variable defined in a class from another class in Java?

    <p>By using the class name followed by the dot operator and then the variable name</p> Signup and view all the answers

    What is the characteristic of accessing ordinary (non-static) variables in Java?

    <p>They can only be accessed through an instance of the class</p> Signup and view all the answers

    What is the key difference between ordinary variables and static variables in Java?

    <p>Static variables always have an assigned value while ordinary variables can remain uninitialized</p> Signup and view all the answers

    What is the key difference between an ordinary (non-static) variable and a static variable in Java?

    <p>Ordinary variables are unique to each instance of the class, while static variables are shared across all instances of the class</p> Signup and view all the answers

    How are static variables different from non-static variables in terms of memory organization immediately after loading a class in Java?

    <p>Non-static variables have memory allocated for each instance of the class, while static variables have memory allocated only once for the entire class</p> Signup and view all the answers

    Which keyword do you use to declare a static variable in a class?

    <p>static</p> Signup and view all the answers

    What happens to static variables when the Java machine finishes loading a class?

    <p>They remain unchanged and continue to exist throughout the program's execution</p> Signup and view all the answers

    In Java, how can you access a static variable defined in a class from another class?

    <p>By writing the name of the class followed by the variable name without creating an instance of the class</p> Signup and view all the answers

    Study Notes

    Class Loading and Static Variables

    What Happens When a Class is Loaded into Memory?

    • When a class is loaded into memory, all static variables are initialized and memory is allocated for them.
    • Static variables are stored in memory with the class definition, not with instances of the class.

    Static Variables vs. Non-Static Variables

    • Static variables are shared by all instances of a class, whereas non-static variables are unique to each instance.
    • Static variables are stored in a single location in memory, while non-static variables have separate copies in each instance.

    Declaring and Accessing Static Variables

    • The static keyword is used to declare a static variable in a class.
    • Inside the class, static variables can be referred to by their variable name.
    • From another class, static variables can be accessed using the class name, e.g., ClassName.variableName.

    Default Values for Uninitialized Static Variables

    • The default value for an uninitialized static variable of type double is 0.0.
    • The default value for an uninitialized static variable of type boolean is false.

    Memory Organization Difference

    • Immediately after loading a class, static variables are stored in a single location in memory, while non-static variables are stored in separate locations for each instance.

    Accessing Ordinary (Non-Static) Variables

    • Ordinary (non-static) variables can only be accessed through an instance of the class.
    • Each instance of the class has its own copy of ordinary variables.

    What Happens to Static Variables When the Java Machine Finishes Loading a Class?

    • Static variables remain in memory as long as the class is loaded.

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    Description

    Test your knowledge about static variables and their behavior in Java classes. Understand the concepts of static object creation and storage, as well as the difference between static and non-static variables.

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