HugeInteger.java

package patty;

import java.util.Iterator;
import java.util.Vector;

public class HugeInteger {

	private boolean sign;
	//TODO Vector is a super-outdated class..
	private Vector<Integer> vector;
	
	
	private HugeInteger(boolean sign, Vector<Integer> vector) {
		this.sign = sign;
		this.vector = new Vector<Integer>(vector.size());

		for(int i = vector.size() -1 ; i >= 0 ; i--)
		{
			this.vector.add(vector.get(i));
		}
		
	}
	
	public String toString() {
		StringBuilder sb = new StringBuilder();
		
		if (sign) {
			sb.append("+");
		} else {
			sb.append("-");
		}
		Iterator<Integer> it = vector.iterator();
		while(it.hasNext()) {
			sb.append(it.next());
		}
		
		return sb.toString();
	}
	
	public static HugeInteger parse(String s) {
		if (s == null) {
			throw new IllegalArgumentException("s must not be null!");
		}
		boolean sign;
		int startPos;
		if ('-' == s.charAt(0)) {
			startPos = 1;
			sign = false;
		} else if ('+' == s.charAt(0)) {
			startPos = 1;
			sign = true;
		} else {
			startPos = 0;
			sign = true;
		}
		Vector<Integer> vector = new Vector<>();
		for (int pos=startPos; pos < s.length(); pos++) {
			// based on the description i think the prof wants this fu - actually this is dangerous for any non-ASCII input!
			int digit = s.charAt(pos) - '0';
			vector.add(digit);
		}
		
		return new HugeInteger(sign, vector);
	}
	
	public HugeInteger addition(HugeInteger summand2) {
		Vector<Integer> result = new Vector<Integer>();
		int carryover = 0;
		
		int i;
		for(i=0; i < Math.max(this.vector.size(), summand2.vector.size()); i++) {
			int sum1;
			if (this.vector.size()<i) {
				sum1 = 0;
			} else {
				sum1 = this.vector.get(i);
			}

			int sum2;
			if (summand2.vector.size()<i) {
				sum2 = 0;
			} else {
				sum2 = summand2.vector.get(i);
			}
			
			int sum = carryover + sum1 + sum2;
			carryover = sum / 10;
			result.add(sum % 10);
		}
		
		return new HugeInteger(this.sign, result);
	}
	
}