JavaCore

The basic conditional statements are if, if-else, and else-if, but as an intermediate or advanced Java developer, you should also know about the switch statement and the conditional (ternary) operator. If statement: This is the most basic form of control flow statement. It allows the program to decide to perform an action or not based on whether a condition is true or not. int age = 20; if (age > 18) {     System.out.println("You are an adult"); } In the above code, if the condition age > 18 is true, then the message "You are an adult" is printed. If the condition is false, nothing happens. If-Else statement: The if-else statement provides an alternative option if the if condition is false. int age = 15; if (age > 18) {     System.out.println("You are an adult"); } else {     System.out.println("You are not an adult"); } In this example, if age > 18 is false, then the message "You are not an adult" is printed. Else-If sta

In Java, a wrapper class provides a way to wrap primitive data types into objects. It allows you to use the primitive data types as objects, enabling you to access their associated methods and utilize them in a more flexible manner. The wrapper classes are part of the java.lang package and provide classes for each of the primitive data types. Here's an example that demonstrates how to use a wrapper class in Java: ___________________________________________________________________________________ public class WrapperExample {     public static void main(String[] args) {         // Creating a wrapper object using the Integer wrapper class         Integer myInteger = new Integer(42);         // Accessing the value using wrapper object         int value = myInteger.intValue();         System.out.println( "Value: " + value);         // Using wrapper class methods         String binaryString = myInteger.toBinaryString(42);         System.out.println ("Binary: "

The primary looping statements in Java: while Loop In a while loop, a condition is evaluated before each iteration. If the condition is true, the block of code inside the loop is executed. This continues until the condition becomes false. Here's a simple example: int i = 0; while (i < 5) {     System.out.println (i);     i++; } In this example, i is initially 0. The loop continues to print i and increment it by one as long as i is less than 5. do-while Loop: In a do-while loop, the block of code is executed once before the condition is checked. If the condition is true, the code block will execute again. This continues until the condition becomes false. Here's a simple example: int i = 0; do {     System.out.println (i);     i++; } while (i < 5); In this example, even if i was initially 5 or greater, the code within the loop would still run once because the condition isn't checked until after the code block has been executed. for Loop: A for loop has three parts:

Data Type And Variable: In Java, the fundamental components of any program include variables and data types. A variable is like a container that holds a value, and the data type specifies what kind of data that container can hold. Here is a simple analogy: you can think of a variable as a box and the data type as the label on the box that tells you what kind of items can be stored inside. Data Types Data types in Java are categorized into two types: Primitive Data Types: These include byte, short, int, long, float, double, boolean, and char. Non-Primitive Data Types (or Reference types): These include String, Array, Class, Interface, etc. Let's see a simple description for each primitive data type: byte: The byte data type is an 8-bit signed two's complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). short: The short data type is a 16-bit signed two's complement integer. It has a minimum value of -32,768 and a maximum value of 32,767

In Java, an identifier is a name given to a variable, method, class, or any other user-defined item. The name must be unique and help to identify the purpose of the item it's associated with. Here are some basic rules to define a valid identifier in Java:  1)      Identifiers must start with a letter (A to Z or a to z), currency character ($) or an underscore (_).  2)      After the first character, identifiers can have any combination of characters.  3)      A keyword cannot be used as an identifier.  4)      Most importantly, identifiers are case sensitive.  5)      Examples of illegal identifiers: 123abc, -a1b2c3, void, etc.  Now, let's see some examples of valid and invalid identifiers: In the first part, myVariable, _name, $salary, and isActive are valid identifiers. They are following the rules of naming identifiers. In the second part, 123abc, -name, #salary, and void are invalid identifiers. They are breaking the rules of naming identifiers. The compiler will throw an

  Design Patterns And Principles Design patterns are reusable solutions to common problems that occur in software design. They can speed up the development process by providing tested, proven development paradigms, and provide a way for developers to communicate using well-known names for these patterns. Here's an overview of several important design patterns in Java: Singleton Pattern:  The Singleton Pattern ensures that a class has only one instance and provides a global point of access to it. Here's a simple example of a Singleton Pattern in Java: Factory Pattern:  The Factory Method Pattern defines an interface for creating an object, but allows subclasses to decide which class to instantiate. The Factory method lets a class defer instantiation to subclasses. Here's a simple example of a Factory Pattern in Java: Observer Pattern:  The Observer Pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified