Uninitialized Variable Error

public static MathExpression makeExpression(StringTokenizer token){
		MathExpression total;
		if(token.hasMoreTokens() != true)
			return null;
		else{
			String temp;
			String express = "+-*/";
			temp = token.nextToken();
			if(temp.length() == 1 && express.indexOf(temp) >= 0){
				switch(temp){
				case "+" : total = new MathBinaryExpression.AddExpression(makeExpression(token), makeExpression(token));
				break;
				case "-" : total = new MathBinaryExpression.SubExpression(makeExpression(token), makeExpression(token));
				break;
				case "*" : total = new MathBinaryExpression.MultExpression(makeExpression(token), makeExpression(token));
				break;
				case "/" : total = new MathBinaryExpression.DivExpression(makeExpression(token), makeExpression(token));
				break;
				}
			}
		}
	return total;
	}

My compiler tells me that when I return total, it is wrong and uninitialized. But aren't I initializing it inside of my switch statement?

Please let me know how I can fix this and what I am doing wrong.