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Conditional Statements in Java

Introduction​

Conditional statements in Java are used to execute different blocks of code based on certain conditions. These statements allow you to control the flow of your program and make decisions during runtime.

Types of Conditional Statements​

If Statement​

The if statement evaluates a boolean expression and executes a block of code if the expression is true.

Syntax:

if (condition) {
    // code to be executed if the condition is true
}

Example:

int number = 10;
if (number > 0) {
    System.out.println("The number is positive.");
}

If-Else Statement​

The if-else statement provides an alternative block of code that executes if the boolean expression is false.

Syntax:

if (condition) {
    // code to be executed if the condition is true
} else {
    // code to be executed if the condition is false
}

Example:

int number = -10;
if (number > 0) {
    System.out.println("The number is positive.");
} else {
    System.out.println("The number is negative or zero.");
}

If-Else-If Ladder​

The if-else-if ladder allows you to check multiple conditions in sequence. The first condition that evaluates to true will have its corresponding block executed.

Syntax:

if (condition1) {
    // code to be executed if condition1 is true
} else if (condition2) {
    // code to be executed if condition2 is true
} else {
    // code to be executed if all conditions are false
}

Example:

int number = 0;
if (number > 0) {
    System.out.println("The number is positive.");
} else if (number < 0) {
    System.out.println("The number is negative.");
} else {
    System.out.println("The number is zero.");
}

Nested If Statements​

You can nest if or if-else statements within another if or if-else statement to create more complex conditions.

Syntax:

if (condition1) {
    // code to be executed if condition1 is true
    if (condition2) {
        // code to be executed if condition2 is true
    }
}

Example:

int number = 5;
if (number > 0) {
    if (number % 2 == 0) {
        System.out.println("The number is positive and even.");
    } else {
        System.out.println("The number is positive and odd.");
    }
}

Switch Statement​

The switch statement is used to execute one block of code among many based on the value of a variable or expression. It is a cleaner alternative to using multiple if-else-if statements.

Syntax:

switch (expression) {
    case value1:
        // code to be executed if expression equals value1
        break;
    case value2:
        // code to be executed if expression equals value2
        break;
    // you can have any number of case statements
    default:
        // code to be executed if none of the cases match
        break;
}

Example:

int day = 3;
switch (day) {
    case 1:
        System.out.println("Monday");
        break;
    case 2:
        System.out.println("Tuesday");
        break;
    case 3:
        System.out.println("Wednesday");
        break;
    case 4:
        System.out.println("Thursday");
        break;
    case 5:
        System.out.println("Friday");
        break;
    case 6:
        System.out.println("Saturday");
        break;
    case 7:
        System.out.println("Sunday");
        break;
    default:
        System.out.println("Invalid day");
        break;
}

Conclusion​

Conditional statements are essential for controlling the flow of your Java programs. By using if, if-else, if-else-if, nested if statements, and switch statements, you can make your programs more dynamic and responsive to different conditions.


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