Method evaluate

ParsingABooleanExpression.java:26–42

(ArrayList<Character> list ,char op)

        return stack.peek() == 't';
    }
    public char evaluate(ArrayList<Character> list ,char op){
        if(op == '&'){
            if(find(list,'f')){
                return 'f';
            }else{
                return 't';
            }
        } else if(op == '|'){
            if(find(list,'t')){
                return 't';
            }else{
                return 'f';
            }
        }else{ // not
            return (list.get(0)=='t'?'f':'t');
        }
    }
    public boolean find(ArrayList<Character> list ,char val){
        for(char ch : list){
            if(ch == val){