Beginner Java Concepts

Loops

Loops are useful when you want to do the same thing, just many times. If you already know exactly how many times you want the loop to run / iterate, you should use a for loop. If you want the loop to be scalable for varying sizes / iterations, use a while loops. If you want a process to happen once and THEN a loop, use a do while loop. However, do while loops might not exist in other languages. There are ways to simulate a do while loop, as well as simulate any type of loop (and even recursion) with the other types.

public static void forLoop(int size) {
	
	for(int i = 0; i < size; i++) {
		System.out.println(i);
	}
	
}

public static int whileLoop(int size) {
	
	if(size <= 0) {
		System.out.println(size);
		return 0;
	}
	
	while(size > 0) {
		System.out.println(size);
		size--;
	}
	
	return 0;
	
}

public static int doWhileLoop(int size) {
	
	// Error handling for input less than zero -> infinite loop
	if(size <= 0) {
		System.out.println(size);
		return 0;
	}
	
	do {
		System.out.println(size);
		size--;
	} while(size > 0);
	
	return 0;
	
}

public static int recursion(int size) {
	
	System.out.println(size);
	if(size == 0) {
		return 0;
	} else {
		return recursion(size - 1);
	}

}

public static void main(String[] args) {
	
	System.out.println("For Loop of 5: ");
	forLoop(5);
	System.out.println("While Loop of 8: ");
	whileLoop(8);
	System.out.println("Do While Loop of 20: ");
	doWhileLoop(20);
	System.out.println("Recursion of 15: ");
	doWhileLoop(15);

}