[java] 20. Valid Parentheses

import java.util.Stack;

class Valid_Parantheses {
    public boolean isValid(String s) {
        Stack<Character>stack = new Stack<Character>(); 
        for(char c : s.toCharArray()){
            if(c == '('){
                stack.push(')');
            }else if(c == '['){
                stack.push(']');
            }else if(c == '{'){
                stack.push('}');
            }else if(stack.isEmpty() || stack.pop()!= c){
                return false; 
            }
        }
        return stack.isEmpty();
    }
}

 

※ toCharArray() : The Java string toCharArray() method converts the given string into a sequence of characters. The returned array length is equal to the length of the string. 

return: returns a newly allocated character array.

 

※isEmpty(): Java.lang.String.isEmpty() String method checks whether a String is empty or not. This method returns true if the given string is empty, else it returns false. (Null and empty is not the same)