Parenthesis/Brackets Matching using Stack algorithm

Question

For example if the parenthesis/brackets is matching in the following:

({})
(()){}()
()

and so on but if the parenthesis/brackets is not mat

Answer 1

public static boolean isValidExpression(String expression) {
    Map openClosePair = new HashMap();
    openClosePair.put(')', '(');
    openClosePair.put('}', '{');
    openClosePair.put(']', '[');        
    Stack stack = new Stack();
    for(char ch : expression.toCharArray()) {
        if(openClosePair.containsKey(ch)) {
            if(stack.pop() != openClosePair.get(ch)) {
                return false;
            }
        } else if(openClosePair.values().contains(ch)) {
            stack.push(ch); 
        }
    }
    return stack.isEmpty();
}