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Beginner Java Concepts

a-Rye
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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);

}
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