java - 使用包含括号的列表将特定括号(左括号、右括号)存储在堆栈中

Question

    static List<String> openingBrackets = new ArrayList<String>();
    static List<String> closingBrackets = new ArrayList<String>();

    public static final String quit = ""; // to be used in sentinel loop

    public static void main(String[] args)
    {
        Scanner scanner = new Scanner(System.in);

        // list containing all the opening brackets
        openingBrackets.add("(");
        openingBrackets.add("{");
        openingBrackets.add("[");
        openingBrackets.add("<");
        System.out.println(openingBrackets);

        // list that contains the closing brackets
        closingBrackets.add(")");
        closingBrackets.add("}");
        closingBrackets.add("]");
        closingBrackets.add(">");
        System.out.println(closingBrackets);

        String sent = "value"; // some dummy value assigned to sent.

        // creating a stack to store the opening brackets
        Stack stackOpening = new Stack();

        // creating a stack to store the closing brackets
        Stack stackClosing = new Stack(); 

        while (!sent.equals(quit))
        {
            System.out.println("Enter a string to test:");
            sent = scanner.nextLine();

            for (int i=0; i<sent.length(); i++)
            {
                char c = sent.charAt(i);

                if (! openingBrackets.contains(c))
                {
                    // push the opening brackets in the String sent 
                    // in the Stack for opening brackets

                    stackOpening.push(c); 
                }

                if (! closingBrackets.contains(c))
                {
                    // push only the closing brackets in the String
                    // in the stack for closing brackets

                    stackClosing.push(c);
                }
            }
        }
    }
}

Sample input:

• (< [ { } ( { > ) ] >

Sample output:

• 堆栈(用于左括号):[ (, <, [, {, }, (, { ]
• 堆栈(用于右括号):[ >, ), ], > ]

However, when printing the two stacks separately; it outputs

• [ (, <, [, {, }, (, {, >, ), ], > ]对于两个堆栈

Answer 1

openingBrackets 和 openingBrackets 是 Collection s of Strings。无论您如何检查，这些集合是否包含 Character s:

char c = sent.charAt(i);

if (! openingBrackets.contains(c))

由于Collection不包含任何Character，因此找不到匹配项，这就是为什么所有元素都添加到两个Stack中的原因。

要解决此问题，请在测试之前创建 openingBrackets 和 lookingBrackets Collection 的 Character 或将 c 转换为 String(如果它包含在这些 Collection 之一中)。

(大多数 Collection 使用 equals 方法检查它们是否包含元素，对于 String 和 Character 仅返回 true(如果两个实例属于同一类型)