Control Statements in Java

Selection, iteration, and jump statements along with method definitions in Java.

Selection Statements

if-else

if (condition) {
    // executes when condition is true
} else {
    // executes when condition is false
}

switch-case

switch (variable) {
    case value1:
        // statements
        break;
    case value2:
        // statements
        break;
    default:
        // default statements
}

Iteration Statements

• for loop — Known iteration count.
• while loop — Condition checked before each iteration.
• do-while loop — Executes at least once, condition checked after.
• Enhanced for loop — Iterates over arrays and collections.

Jump Statements

• break — Exits the current loop or switch.
• continue — Skips the current iteration.
• return — Exits the current method.

Methods

Methods define reusable blocks of code with a name, parameters, and a return type:

returnType methodName(parameters) {
    // method body
    return value;
}

Scope determines where variables are accessible — at the method level or within a block ({}).

Example

// ControlDemo.java
// Demonstrates if-else and for loop in Java.

public class ControlDemo {
	public static void main(String[] args) {
		// If-else statement
		int number = 5;
		if (number > 0) {
			// Positive number
			System.out.println("Positive number");
		} else {
			// Non-positive number
			System.out.println("Non-positive number");
		}

		// For loop
		for (int i = 1; i <= 3; i++) {
			// Print i
			System.out.println("i = " + i);
		}
	}
}

Full source: examples/03-control-statements/ControlDemo.java