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所以我已经按照其他人的说法修改了我的代码（在实际查看了这个问题的算法之后），我的解决方案现在正在运行！但是我现在必须打印出错误消息。如果说你有输入，我已经完成了错误消息：“{ } < )”它将返回 ) 不匹配 < 但我还必须通知左括号保持未闭合并且右括号没有相应的左括号。我不确定如何使用我当前的实现来做到这一点。任何帮助都会很棒！谢谢，凯尔。

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.EmptyStackException; 
import java.util.Stack; //using java's default stack in this case as it has more     extraneous error checking

    public class Question3 {
private static final String OPEN = "([{<";
private static final String CLOSED = ")]}>";

public static void main(String[] args) throws IOException {
    BufferedReader inKb = new BufferedReader(new InputStreamReader(
            System.in));

    System.out.println("Enter a test string:");
    String input = inKb.readLine().replaceAll(" ", "");

    System.out.print(parChecker(input));
    // System.out.println(successful);
}

private static boolean isOpen(char ch) {
    return OPEN.indexOf(ch) >= 0;
}

private static boolean isClosed(char ch) {
    return CLOSED.indexOf(ch) >= 0;
}

private static boolean matches(char open, char close) {
    int openIndex = OPEN.indexOf(open);
    int closeIndex = CLOSED.indexOf(close);

    return (openIndex == closeIndex);
}

public static boolean parChecker(String input) {
    boolean balanced = true; // is stack balanced (matching parentheses)
    boolean ret = false; // return value

    Stack<Character> stack = new Stack<Character>();

    for (int i = 0; i < input.length() && balanced; i++) { // if it's not
                                                            // balanced stop
                                                            // searching

        char bracket = input.charAt(i);
        if (isOpen(bracket)) {
            stack.push(bracket);
        } else if (stack.isEmpty())
            balanced = false;

        else {
            char top = stack.pop();
            if (matches(top, bracket) == false) {
                System.out.println("Error: '" + bracket
                        + "' does not match with '" + top + "'.");
                balanced = false;

            }
        }
    }
    if (balanced && stack.isEmpty()) {
        System.out
                .println("The string is correct! There are no mismatched brackets");
        ret = true;
    } else
        ret = false;

    return ret;
}

}

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