I am trying to use the summer to practice more Java to get better by learning how to code algorithms. I have this problem where I add elements to my ArrayList but somehow the first number I add also sets the number of positions in my list which I want to avoid. I only want the 0th index to contain the number 5. I seem to not catch a clue on how to solve this.
public class Algorithms {
private ArrayList<Integer> numbers;
public Algorithms() {
numbers = new ArrayList<Integer>();
numbers.add(5);
numbers.add(4);
bubblesort();
}
public static void main(String args[]) {
new Algorithms();
}
public void bubblesort() {
System.out.println(numbers);
for (int a = 0; a < numbers.size();) {
for (int b = 1; b < numbers.size();) {
int currentNumber = numbers.get(a);
if (currentNumber > numbers.get(b)) {
//Collections.swap(numbers, currentNumber, numbers.get(b));
numbers.set(numbers.get(a), numbers.get(b));
numbers.set(numbers.get(b), numbers.get(a));
a++;
b++;
} else if (currentNumber < numbers.get(b)) {
a++;
b++;
}
System.out.println(numbers);
}
}
}
}
You are not swapping elements correctly. Instead of
numbers.set(numbers.get(a), numbers.get(b));
numbers.set(numbers.get(b), numbers.get(a));
it should be
int temp = numbers.get(a);
numbers.set(a, numbers.get(b));
numbers.set(b, temp);