用户输入括号是否匹配

public class brackets {
    /*算法*/
    public static boolean isMatch(String str) {        
        int i = 0;
        char e, x;
        SqStackClass<Character> st = new SqStackClass<Character>();    //建立一个顺序栈
        while (i < str.length()) {
            e = str.charAt(i);
            if (e == '(' || e == '[' || e == '{') {
                st.push(e);                             //将左括号进栈
            } else {
                if (e == ')') {
                    if (st.empty()) {
                        return false;        //栈空返回false
                    }
                    if (st.peek() != '(') {
                        return false;    //栈顶不是匹配的'('返回false
                    }
                    st.pop();
                }
                if (e == ']') {
                    if (st.empty()) {
                        return false;               //栈空返回false
                    }
                    if (st.peek() != '[') {
                        return false;//栈顶不是匹配的'['返回false
                    }
                    st.pop();
                }
                if (e == '}') {
                    if (st.empty()) {
                        return false;//栈空返回false
                    }
                    if (st.peek() != '{') {
                        return false;//栈顶不是匹配的'{'返回false
                    }
                    st.pop();
                }
            }
            i++;                                        //继续遍历str
        }
        if (st.empty()) {
            return true;//栈空返回true
        }
        else {
            return false;//栈不空返回false
        }
    }
    public static void main(String[] args) {
        System.out.println("-------测试1----------");
        String str = "([)]";
        if (isMatch(str))
            System.out.println(str + "中括号是匹配的");
        else
            System.out.println(str + "中括号不匹配");
        System.out.println("-----------测试2------------");
        str = "([])";
        if (isMatch(str))
            System.out.println(str + "中括号是匹配的");
        else
            System.out.println(str + "中括号不匹配");
    }