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Lesson 2: Java Conditional Statements (if-else and Nested if-else)

Introduction to Conditional Statements:
In Java programming, conditional statements play a pivotal role in controlling the flow of a program based on certain conditions. These statements allow you to make decisions and execute specific code blocks depending on whether certain conditions are met. Two fundamental conditional constructs are the if-else statement and its advanced version, the nested if-else statement.

If-Else Statement:
The if-else statement is a foundational construct that lets you execute one block of code if a condition evaluates to true and another block if the condition evaluates to false.

java

int age = 18;

if (age 18) {
System.out.println("You are an adult.");
} else {
System.out.println("You are not yet an adult.");
}
In this example, the program checks if age is greater than or equal to 18. If the condition is true, it prints "You are an adult." Otherwise, it prints "You are not yet an adult."

Nested If-Else Statement:
A nested if-else statement occurs when you place an if-else statement inside another if or else block. This construct allows for more complex decision-making.

java

int age = 20;
boolean hasLicense = true;

if (age 18) {
if (hasLicense) {
System.out.println("You can drive.");
} else {
System.out.println("You cannot drive without a license.");
}
} else {
System.out.println("You are too young to drive.");
}
In this example, the program first checks if age is greater than or equal to 18. If the condition is met, it further checks if hasLicense is true. If both conditions are true, it prints "You can drive." If the first condition is true but the second is false, it prints "You cannot drive without a license." If the first condition is false, it prints "You are too young to drive."

Use Cases and Benefits:

Decision Making: Conditional statements are used to make decisions in a program based on various conditions.
User Interaction: They are useful for responding to user input, such as validating data or displaying appropriate messages.
Dynamic Behavior: Conditional statements allow a program to adapt and respond dynamically during runtime.
Chaining Conditions:
You can chain multiple conditions using logical operators like && (AND) and || (OR) to create more complex decision structures.

java
Copy code
int score = 85;

if (score 90) {
System.out.println("Excellent!");
} else if (score 70 && score 90) {
System.out.println("Good job!");
} else {
System.out.println("Keep practicing.");
}
Nested Conditional Complexity:
While nested conditional statements provide flexibility, excessive nesting can make code hard to understand. Strive for clarity and avoid unnecessary complexity.

Conclusion:
Conditional statements, including the if-else and nested if-else constructs, are vital tools in Java programming for making decisions and controlling program flow. They enable your code to respond dynamically to different scenarios. By mastering these constructs, you gain the ability to build versatile and responsive programs that cater to a variety of conditions.