Conditional Statements

Conditional statements allow your program to branch out. Think of it like a flow chart.

• If it is raining, then take an umbrella.

• Else, if it is sunny, then wear sunglasses.

• Else, just walk normally.

In Java, we primarily use if, else if, else, and switch.

The 3 Main Types of Logic Gates

1. The if and else blocks

This is the most common way to control flow. It checks a condition (which must be true or false).

• if (condition): Runs the code inside {} only if the condition is true.

• else if (anotherCondition): Checked only if the first if was false.

• else: The "safety net." It runs if none of the above conditions were met.

2. The Ternary Operator (The Shortcut)

If you have a very simple if-else that just assigns a value, you can do it in one line: variable = (condition) ? valueIfTrue : valueIfFalse;

3. The switch Statement (The Multi-Choice)

If you are checking a single variable against many specific values (like a menu or days of the week), switch is much cleaner than writing ten else if statements.

The Code Example:

public class ConditionalsDemo {
    public static void main(String[] args) {
        int examScore = 85;
        char grade;

        // --- 1. Using If-Else If-Else ---
        if (examScore >= 90) {
            grade = 'A';
        } else if (examScore >= 80) {
            grade = 'B';
        } else if (examScore >= 70) {
            grade = 'C';
        } else {
            grade = 'F';
        }

        System.out.println("With a score of " + examScore + ", your grade is: " + grade);

        // --- 2. Using a Switch Statement ---
        int dayOfWeek = 3; // Let's say 1=Mon, 2=Tue, 3=Wed...
        String dayName;

        switch (dayOfWeek) {
            case 1: dayName = "Monday"; break;
            case 2: dayName = "Tuesday"; break;
            case 3: dayName = "Wednesday"; break;
            case 4: dayName = "Thursday"; break;
            case 5: dayName = "Friday"; break;
            default: dayName = "Weekend!"; break;
        }

        System.out.println("Today is: " + dayName);

        // --- 3. The Ternary Operator ---
        int age = 19;
        String status = (age >= 18) ? "Adult" : "Minor";
        System.out.println("User Status: " + status);
    }
}

Expected Output:

With a score of 85, your grade is: B
Today is: Wednesday
User Status: Adult

Conditionals turn a "script" into an "application." Every time you see a "Premium Member" feature locked on a website, or a game character dies when health hits zero, there is an if statement behind the scenes checking that logic.

Note on break: In the switch statement, always remember the break; keyword. If you forget it, Java will "fall through" and execute all the code in the cases below it!