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Showing posts with the label Java Design Patterns

Singleton Design Pattern: Best Practices, Example, ways to break and Prevention Strategies in Java

Singleton Design Pattern Problem: Ensure a class has only one instance and provide a global point of access to that instance. Solution: Create a class with a private constructor, a private static instance variable, and a public static method to provide access to the single instance. Key Points to Make a Singleton Class in Java: Private constructor to prevent external instantiation. Private static instance variable to hold the single instance. Public static method to provide access to the instance. Ways to Break a Singleton: Reflection: Using reflection to access the private constructor. Serialization: When a Singleton is serialized and deserialized, it creates a new instance. Cloning: Creating a clone of the Singleton instance. Prevention Techniques: Lazy Initialization with Double-Checked Locking: Use double-checked locking for lazy initialization to ensure thread safety. Enum Singleton: Implement the Singleton using an enum to handle serialization, reflection, and cloning. Ove...
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Exploring Proxy Design Pattern in Java with Real-World Examples with sample code

Proxy Design Pattern Problem: Control access to an object by providing a surrogate or placeholder for it. Solution: Create a proxy class that acts as an intermediary between the client and the actual object. The proxy can perform additional operations before or after forwarding the request to the real object. Key Points to Implement a Proxy: Proxy class implementing the same interface as the real object. Proxy holds a reference to the real object. Proxy controls access to the real object and may perform additional actions. Predefined Use-Case in Java: A common use of the Proxy pattern is the java.lang.reflect.Proxy class, which allows the creation of dynamic proxy instances for interfaces at runtime. Example Program: interface Internet { void connectTo(String serverHost) throws Exception; } class RealInternet implements Internet { @Override public void connectTo(String serverHost) { System.out.println("Connecting to " + serverHost); } } class Prox...
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Using Java 8 Streams to Find the Second-Highest Salary in an Employee List

To find the second-highest salary from a list of employees using Java 8 streams, you can follow these steps: Create a list of employees with their salaries. Use Java 8 streams to sort the employees by salary in descending order. Skip the first element (which is the employee with the highest salary). Get the first element of the remaining stream (which is the employee with the second-highest salary). Example code: java import java.util.ArrayList; import java.util.List; class Employee { private String name; private double salary; public Employee (String name, double salary) { this .name = name; this .salary = salary; } public double getSalary () { return salary; } } public class SecondHighestSalary { public static void main (String[] args) { List<Employee> employees = new ArrayList <>(); employees.add( new Employee ( "John" , 60000.0 )); employees.add( new Employe...
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Java Data Structures and Algorithms: A Practical Guide with Examples and Top Interview Questions"

Data Structures and Algorithms in Java Understanding Data Structures ArrayList When to Use: Use ArrayList when you need a dynamic array that can grow or shrink in size. It's efficient for random access but less efficient for frequent insertions and deletions. Example Code: java List<String> arrayList = new ArrayList <>(); arrayList.add( "Java" ); arrayList.add( "Data Structures" ); arrayList.add( "Algorithms" ); LinkedList When to Use: LinkedList is suitable for frequent insertions and deletions. It provides better performance than ArrayList in scenarios where elements are frequently added or removed from the middle of the list. Example Code: java LinkedList<String> linkedList = new LinkedList <>(); linkedList.add( "Java" ); linkedList.add( "Data Structures" ); linkedList.add( "Algorithms" ); HashMap When to Use: Use HashMap for fast retrieval of data based on a key. It is efficient for loo...
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Java fundamentals, such as variables, data types, control flow, and methods

  Introduction: Java, with its "write once, run anywhere" philosophy, has been a cornerstone of modern software development for decades. For newcomers embarking on their coding journey, a solid grasp of Java fundamentals is crucial. In this blog post, we'll unravel the core concepts, including variables, data types, control flow, and methods, providing a robust foundation for anyone venturing into Java programming. 1. Variables and Data Types: Variables: In Java, a variable is a container for storing data values. Before using a variable, you must declare its type and name. Java supports various data types, such as int , double , boolean , and String . Example: java int age = 25 ; double price = 19.99 ; boolean isJavaFun = true ; String greeting = "Hello, Java!" ; 2. Data Types: Primitive Data Types: int: Used for integer values. double: Used for floating-point numbers. boolean: Represents true or false. char: Represents a single character. Examp...
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