linkedliststack.java

来自「java 完全探索的随书源码」· Java 代码 · 共 55 行

import java.util.LinkedList;
import java.util.EmptyStackException;

public class LinkedListStack {

  private LinkedList listDelegate = new LinkedList();

  public boolean empty() {
    return listDelegate.isEmpty();
  }

  // return the element on top of the stack without removing it
  public Object peek() {
    if ( !this.empty() ) {
      return listDelegate.getFirst();
    }
    throw new EmptyStackException();
  }

  // return the element on top of the stack and remove it
  public Object pop() {
    if ( !this.empty() ) {
      return listDelegate.removeFirst();
    }
    throw new EmptyStackException();
  }

  // place an object on top of the stack
  public Object push(Object item) {
    listDelegate.addFirst(item);
    return item;
  }

  // look for an object in the stack
  public int search(Object item) {
    return listDelegate.indexOf(item);
  }

  public static void main( String args[] ) {
    LinkedListStack stack = new LinkedListStack();
    // push 5 elements onto the stack
    for ( int i=0; i<5; i++ ) {
      stack.push( new Integer(i) );
    }

    System.out.println("Peek at the top of the stack: " + stack.peek() );

    // empty the stack
    while ( !stack.empty() ) {
      System.out.println("Pop: " + stack.pop() );
    }
  }

}