A complicated method can be made more readable by making it a composition of smaller methods:

void add(Object element) {
	if (!readOnly) {
		int newSize = size + 1;
		if (newSize > elements.length) {
			Object[] newElements = new Object[elements.length + 10];
			for (int i = 0; i < size; i++) {
				newElements[i] = elements[i];
			}
			elements = newElements;
		}
		elements[size++] = element;
	}
}

void add(Object element) {
	if (readOnly)
		return;
	if (atCapacity())
		grow();
	addElement(element);
}

A method should not have too many nested blocks of code. To make it more comprehensible extract private methods, so that it will be a composition of a few shorter, lower level methods. Improved method looks like a cooking recipe and can be understood at a glance.

J. Kerievsky, Refactoring to Patterns