算法（Algorithms）第4版 练习 1.3.1

package com.qiusongde;

import java.util.Iterator;
import java.util.NoSuchElementException;

import edu.princeton.cs.algs4.StdIn;
import edu.princeton.cs.algs4.StdOut;

public class FixedCapacityStackOfStrings implements Iterable<String> {

    private String[] a;
    private int n;

    public FixedCapacityStackOfStrings(int cap) {
        a = new String[cap];
        n = 0;
    }

    public void push(String item) {
        if(isFull())
            throw new IndexOutOfBoundsException("FiexdCapcityStackOfString is Full");
        a[n++] = item;
    }

    public String pop() {
        if(isEmpty())
            throw new NoSuchElementException("FiexdCapcityStackOfString is empty");
        return a[--n];
    }

　　//1.3.1
    public boolean isFull() {
        return n == a.length;
    }

    public boolean isEmpty() {
        return n == 0;
    }

    public int size() {
        return n;
    }

    @Override
    public Iterator<String> iterator() {
        return new ReverseArrayIterator();
    }

    private class ReverseArrayIterator implements Iterator<String> {

        private int i = n;

        @Override
        public boolean hasNext() {
            return i > 0;
        }

        @Override
        public String next() {
            return a[--i];
        }

    }

    public static void main(String[] args) {

        int max = 5;
        FixedCapacityStackOfStrings stack = new FixedCapacityStackOfStrings(max);
        StdOut.println("stack initialized max size is:" + max);

        while (!StdIn.isEmpty()) {

            String item = StdIn.readString();

            if (!item.equals("-")) {
                if(stack.isFull())
                    StdOut.println("push error, stack full");
                else {
                    stack.push(item);
                    StdOut.println("push success:" + item + " size:" + stack.size());

                    StdOut.print("Left on stack: ");
                    for (String s : stack) {
                        StdOut.print(s + " ");
                    }
                    StdOut.println();
                }
            } else {
                if(stack.isEmpty())
                    StdOut.println("pop error, stack empty");
                else {
                    StdOut.println("pop success:" + stack.pop() + " size:" + stack.size());

                    StdOut.print("Left on stack: ");
                    for (String s : stack) {
                        StdOut.print(s + " ");
                    }
                    StdOut.println();
                }
            }

        }

    }

}

stack initialized max size is:5
to
push success:to size:1
Left on stack: to
be
push success:be size:2
Left on stack: be to
or
push success:or size:3
Left on stack: or be to
not
push success:not size:4
Left on stack: not or be to
to
push success:to size:5
Left on stack: to not or be to
be
push error, stack full
-
pop success:to size:4
Left on stack: not or be to
-
pop success:not size:3
Left on stack: or be to
-
pop success:or size:2
Left on stack: be to
-
pop success:be size:1
Left on stack: to
-
pop success:to size:0
Left on stack:
-
pop error, stack empty