if statements

If Statements in Java

The if statement is one of the most fundamental control structures in Java. It allows you to execute a block of code based on whether a condition is true or false. In this section, we'll explore the different types of if statements in Java and how to use them effectively with examples.

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1. What is an if Statement?

An if statement in Java is used to make decisions in your code. It evaluates a condition (an expression that returns a boolean value: true or false), and if the condition is true, the block of code inside the if statement is executed. If the condition is false, the code inside the if statement is skipped.

Syntax:

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

Example:

int age = 18;

if (age >= 18) {
    System.out.println("You are eligible to vote.");
}

In this example, the condition age >= 18 is checked. Since the condition is true, the message "You are eligible to vote." is printed.

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2. if-else Statement

The if-else statement allows you to execute one block of code if the condition is true and another block of code if the condition 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 age = 16;

if (age >= 18) {
    System.out.println("You are eligible to vote.");
} else {
    System.out.println("You are not eligible to vote.");
}

In this example, the condition age >= 18 is false, so the message "You are not eligible to vote." is printed.

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3. if-else if-else Ladder

The if-else if-else ladder is used when you have multiple conditions to check. It allows you to execute different blocks of code depending on which condition is true.

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 none of the above conditions are true
}

Example:

int marks = 85;

if (marks >= 90) {
    System.out.println("Grade: A");
} else if (marks >= 75) {
    System.out.println("Grade: B");
} else if (marks >= 60) {
    System.out.println("Grade: C");
} else {
    System.out.println("Grade: D");
}

In this example, the program checks multiple conditions to determine the grade based on the value of marks.

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4. Nested if Statements

You can place one if statement inside another if statement. This is called a nested if statement. It allows you to check for a condition inside another condition.

Syntax:

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

Example:

int number = 10;

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

In this example, the program first checks if the number is positive. If it is, it then checks if the number is even.

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5. Ternary Operator (Shortcut for if-else)

The ternary operator is a shorthand way of writing an if-else statement. It takes three operands and is used to evaluate a condition and return one of two values based on whether the condition is true or false.

Syntax:

variable = (condition) ? value_if_true : value_if_false;

Example:

int age = 20;
String result = (age >= 18) ? "Eligible to vote" : "Not eligible to vote";
System.out.println(result);

In this example, the ternary operator checks if age >= 18. If true, it assigns "Eligible to vote" to result; otherwise, it assigns "Not eligible to vote".

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Conclusion

The if statement is a powerful tool for making decisions in your Java programs. By using if, if-else, and if-else if-else statements, you can control the flow of your program based on various conditions. Nested if statements and the ternary operator provide additional flexibility for more complex decision-making.

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