static String toHex(int n) {
    	//创建栈
    	Deque<String> stack = new ArrayDeque<>();
    	
    	while(n > 0)
    	{
    		stack.push(Integer.toHexString(n%16));
    		n /= 16;
    	}
    	
    	StringBuilder answer = new StringBuilder();

    	int size = stack.size();
    	for(int i = 0; i < size; i++) {
    		answer.append(stack.pop());
		}
    	
    	return answer.toString();
    }