brackets  () {} []
扫描字符串
左括号入栈 push
遇到右括号，左括号出栈 pop ，验证是否匹配 
扫描完毕 查看栈是否为空，为空则全部匹配成功，否则返回false ​​​​



import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Map;
import java.util.Set;

public class BracketsMatch {

    private static final Map<Character, Character> map = new HashMap<>();
    private static final Set<Character> leftBrackets = new HashSet<>();
    private static final Set<Character> rightBrackets = new HashSet<>();

    static {
        map.put(')', '(');
        map.put(']', '[');
        map.put('}', '{');

        rightBrackets.addAll(map.keySet());
        leftBrackets.addAll(map.values());
    }

    private static boolean isValid(String str) {
        if (str == null || str.isEmpty()) {
            return false;
        }
        int length = str.length();
        if (length % 2 != 0) {
            return false;
        }
        Deque<Character> stack = new LinkedList<>();
        for (int i = 0; i < length; i++) {
            char ch = str.charAt(i);
            // 非法字符
            if (!leftBrackets.contains(ch) && !rightBrackets.contains(ch)) {
                return false;
            }
            // 左括号入栈
            if (leftBrackets.contains(ch)) {
                stack.push(ch);
                continue;
            }
            // 栈为空 不匹配 
            if (stack.isEmpty()) {
                return false;
            }
            // 括号不匹配
            if (!stack.pop().equals(map.get(ch))) {
                return false;
            }     
        }
        // 非空 匹配失败
        if (!stack.isEmpty()) {
            return false;
        }
        return true;
    }

    public static void main(String[] args) {
        System.out.println(isValid(null));
        System.out.println(isValid(""));
        System.out.println(isValid(" "));
        System.out.println(isValid("("));
        System.out.println(isValid("["));
        System.out.println(isValid("{"));
        System.out.println(isValid("(]"));
        System.out.println(isValid("(}"));
        System.out.println(isValid("{[(())]"));
        System.out.println(isValid("{[(())"));

        System.out.println();

        System.out.println(isValid("()"));
        System.out.println(isValid("[]"));
        System.out.println(isValid("{}"));
        System.out.println(isValid("(())"));
        System.out.println(isValid("{(())}"));
        System.out.println(isValid("{[(())]}"));

    }

}


完整代码
https://gitee.com/dyyx/hellocode/blob/master/web/tech/DS/dsjava/src/main/java/dyyx/BracketsMatch.java