Control Structures

Control Flow

Use if/else, switch statements, and loops to control the flow of your Java programs.

if / else

The most basic control structure. Execute code based on a condition.

switch Statement

A cleaner alternative to long if/else chains when comparing one value against multiple options.

Java 14+ supports switch expressions with a cleaner arrow syntax.

Loops

for — when you know how many iterations
while — while a condition is true
do-while — like while, but runs at least once
for-each — iterate over collections and arrays

Example

java

// if / else
int score = 75;
if (score >= 90) {
    System.out.println("A");
} else if (score >= 80) {
    System.out.println("B");
} else if (score >= 70) {
    System.out.println("C");
} else {
    System.out.println("F");
}

// switch statement
String day = "MONDAY";
switch (day) {
    case "MONDAY":
    case "TUESDAY":
        System.out.println("Weekday");
        break;
    case "SATURDAY":
    case "SUNDAY":
        System.out.println("Weekend");
        break;
    default:
        System.out.println("Midweek");
}

// Switch expression (Java 14+)
String result = switch (day) {
    case "MONDAY", "FRIDAY" -> "Start/end";
    case "SATURDAY", "SUNDAY" -> "Weekend";
    default -> "Midweek";
};

// for loop
for (int i = 0; i < 5; i++) {
    System.out.println(i);
}

// while loop
int count = 0;
while (count < 3) {
    System.out.println("Count: " + count);
    count++;
}

// for-each loop
int[] numbers = {1, 2, 3, 4, 5};
for (int num : numbers) {
    System.out.println(num);
}

Try it yourself — JAVA