Stack 스택

https://ko.wikipedia.org/wiki/%EC%8A%A4%ED%83%9D

스택 - 위키백과, 우리 모두의 백과사전

- 스택의 사전적 의미

stack 1. (보통 깔끔하게 정돈된) 무더기 2. 많음, 다량 3. (깔끔하게 정돈하여) 쌓다; 쌓이다, 포개지다

 

- 후입 선출

https://ko.wikipedia.org/wiki/%ED%9B%84%EC%9E%85_%EC%84%A0%EC%B6%9C

후입 선출 - 위키백과, 우리 모두의 백과사전

 

 

- java.util.Stack

package java.util;

public class Stack<E> extends Vector<E> {

    public Stack() {
    }

    /**
     * Pushes an item onto the top of this stack. This has exactly
     * the same effect as:
     * <blockquote><pre>
     * addElement(item)</pre></blockquote>
     *
     * @param   item   the item to be pushed onto this stack.
     * @return  the {@code item} argument.
     * @see     java.util.Vector#addElement
     */
    public E push(E item) {
        addElement(item);

        return item;
    }

    /**
     * Removes the object at the top of this stack and returns that
     * object as the value of this function.
     *
     * @return  The object at the top of this stack (the last item
     *          of the {@code Vector} object).
     * @throws  EmptyStackException  if this stack is empty.
     */
    public synchronized E pop() {
        E       obj;
        int     len = size();

        obj = peek();
        removeElementAt(len - 1);

        return obj;
    }

    /**
     * Looks at the object at the top of this stack without removing it
     * from the stack.
     *
     * @return  the object at the top of this stack (the last item
     *          of the {@code Vector} object).
     * @throws  EmptyStackException  if this stack is empty.
     */
    public synchronized E peek() {
        int     len = size();

        if (len == 0)
            throw new EmptyStackException();
        return elementAt(len - 1);
    }

    /**
     * Tests if this stack is empty.
     *
     * @return  {@code true} if and only if this stack contains
     *          no items; {@code false} otherwise.
     */
    public boolean empty() {
        return size() == 0;
    }

    /**
     * Returns the 1-based position where an object is on this stack.
     * If the object {@code o} occurs as an item in this stack, this
     * method returns the distance from the top of the stack of the
     * occurrence nearest the top of the stack; the topmost item on the
     * stack is considered to be at distance {@code 1}. The {@code equals}
     * method is used to compare {@code o} to the
     * items in this stack.
     *
     * @param   o   the desired object.
     * @return  the 1-based position from the top of the stack where
     *          the object is located; the return value {@code -1}
     *          indicates that the object is not on the stack.
     */
    public synchronized int search(Object o) {
        int i = lastIndexOf(o);

        if (i >= 0) {
            return size() - i;
        }
        return -1;
    }

    /** use serialVersionUID from JDK 1.0.2 for interoperability */
    @java.io.Serial
    private static final long serialVersionUID = 1224463164541339165L;
}