Skip to main content

Java Exception Handling MCQ Test

  Loading…
Post a Comment

static keyword

In Java, the `static` keyword is used to declare members (variables and methods) that belong to the class rather than to instances of the class. When a member is declared as static, it means that there is exactly one copy of that member shared by all instances of the class. The `static` keyword can be applied to variables, methods, and nested classes. Here's a breakdown of how `static` is used:


1. Static Variables (Class Variables):

   public class MyClass {

       // Static variable

       static int count;


       public MyClass() {

           // Incrementing the static variable in the constructor

           count++;

       }

   }


   In the example above, `count` is a static variable, and its value is shared among all instances of the `MyClass`.


2. Static Methods:


   public class MathUtils {

       // Static method

       public static int add(int a, int b) {

           return a + b;

       }

   }


   The `add` method in the `MathUtils` class is declared as static. It can be called using the class name (`MathUtils.add(2, 3)`) without creating an instance of `MathUtils`.


3. Static Blocks:

   public class Configuration {

       // Static block

       static {

           // Initialization logic

           System.out.println("Initializing configuration...");

       }

   }


   Static blocks are used for static initialization. They are executed when the class is loaded, and they run before the execution of any static method or the creation of any static variable.


4. Static Nested Classes:

   


   public class OuterClass {

       // Static nested class

       static class NestedClass {

           // ...

       }

   }


   A static nested class is associated with its outer class rather than instances of the outer class. It can be instantiated without creating an instance of the outer class.


Key Points:


- Static members belong to the class, not to instances.

- Static members can be accessed using the class name.

- Static methods can only directly call other static methods or access static variables.

- Static members are loaded when the class is first accessed (loaded) by the Java Virtual Machine (JVM).


Here's an example demonstrating the use of static variables and methods:


public class StaticExample {

    // Static variable

    static int instanceCount = 0;


    // Instance variable

    int instanceNumber;


    public StaticExample() {

        // Incrementing instanceCount in the constructor

        instanceCount++;

        // Assigning instanceCount to instanceNumber

        instanceNumber = instanceCount;

    }


    // Static method

    public static void printInstanceCount() {

        System.out.println("Number of instances: " + instanceCount);

    }

}


class Main {

    public static void main(String[] args) {

        // Creating instances of StaticExample

        StaticExample obj1 = new StaticExample();

        StaticExample obj2 = new StaticExample();


        // Accessing static variable using class name

        System.out.println("Accessing static variable: " + StaticExample.instanceCount);


        // Accessing instance variable

        System.out.println("Instance number for obj1: " + obj1.instanceNumber);

        System.out.println("Instance number for obj2: " + obj2.instanceNumber);


        // Accessing static method using class name

        StaticExample.printInstanceCount();

    }

}

Labels:

Comments

Post a Comment

Popular posts from this blog

Passing and Returning Objects in Java Methods

Passing and Returning Objects in Java Methods In Java, objects can be passed as parameters to methods and returned from methods just like other primitive data types. This allows for flexibility and the manipulation of object state within methods. Let's explore how passing and returning objects work in Java. Passing Objects as Parameters When you pass an object as a parameter to a method, you are essentially passing a reference to that object. This means that changes made to the object inside the method will affect the original object outside the method.  Example: class Car {     String model;     Car(String model) {         this.model = model;     } } public class CarProcessor {     // Method to modify the Car object     static void modifyCar(Car car, String newModel) {         car.model = newModel;     }     public static void main(String[] args) {       ...
Post a Comment
Read more

Chained Exceptions

 Chained exceptions, also known as nested exceptions, allow you to associate one exception with another. This feature is useful when you want to provide more context or information about the cause of an exception. In Java, you can chain exceptions using constructors that take a `Throwable` (or its subclasses) as an argument. Syntax: try {     // Code that may throw an exception } catch (ExceptionType1 e1) {     throw new ExceptionType2("Additional information", e1); } Explanation: - Inside a `catch` block, you can create a new exception object and pass the original exception (`e1`) as the cause. - The chained exception (`ExceptionType2`) includes a message and the original exception (`e1`) as its cause. - This technique allows you to preserve the original exception's stack trace and context while providing additional information about the higher-level exception. - Chained exceptions can be caught and processed at higher levels of the call stack, allowing for bet...
Post a Comment
Read more