使用数组实现配置堆栈以构建Koch Snowflake

Question

我正在尝试使用堆栈的想法来构建一个Koch雪花。我让它与链表一起工作，但由于某些原因，我不能让它与数组一起工作。我一直得到一个ArrayIndexOutOfBoundsException 1，然后是0。我似乎找不出我的错误在哪里。任何意见都将不胜感激。谢谢。

class SnowflakeStack extends Frame {

private Stack<Line> line = new ArrayStack();
private LinkedList<Line> complete = new LinkedList<Line>();

public Snowflake() {
    setTitle("Stack-based Snowflake");
    setSize(400, 400);
    addWindowListener(new CloseQuit());
}

public void run() {
    // insert first lines into snowflake
    Point a = new Point(50, 140);
    Point b = new Point(350, 140);
    Point c = new Point(200, 360);

    this.line.push(new Line(a, b));
    this.line.push(new Line(b, c));
    this.line.push(new Line(c, a));

    // now make the snowflake
    while (!this.line.isEmpty()) {
        Line lne = this.line.pop();
        processLine(lne);
        try {
            Thread.sleep(100);
        } catch (Exception exception) {
            System.out.println(exception.getMessage());
        }
        repaint();
    }
}

private void processLine(Line lne) {
    // first compute line lengths
    int dx = (lne.stop.x - lne.start.x) / 3;
    int dy = (lne.stop.y - lne.start.y) / 3;
    if ((dx * dx + dy * dy) < 10) {
        this.complete.addFirst(lne); // line is too small
    } else {
        Point a = new Point(lne.start.x + dx, lne.start.y + dy);
        Point b = new Point(lne.start.x + 3 * dx / 2 + dy, lne.start.y + 3
                * dy / 2 - dx);
        Point c = new Point(lne.start.x + 2 * dx, lne.start.y + 2 * dy);
        this.lines.push(new Line(lne.start, a));
        this.lines.push(new Line(a, b));
        this.lines.push(new Line(b, c));
        this.lines.push(new Line(c, lne.stop));
    }
}

public void paint(Graphics g) {
    Iterator<Line> iter = this.lines.iterator();
    while (iter.hasNext()) {
        Line lne = (Line) iter.next();
        lne.draw(g);
    }
    iter = this.complete.iterator();
    while (iter.hasNext()) {
        Line lne = (Line) iter.next();
        lne.draw(g);
    }
}

public static void main(String[] args) {
    Snowflake snowflake = new Snowflake();
    snowflake.setVisible(true);
    snowflake.run();
}

}

是从堆栈中生成雪花的类。下面是包含数组的类。

public class ArrayStack implements Stack<Line> {

private Line[] lines;
private int top = -1;

/**
 * Creates array of Line objects
 */

public ArrayStack() {
    this.lines = new Line[0];
    top = lines.length;

}

@Override
public boolean isEmpty() {

    return this.lines.length == 0;
}

/**
 * Sees if array is full since not dynamically allocated like a linked list
 * 
 * @return true if array is full
 */

public boolean isFull() {
    return this.size() == this.lines.length;
}

@Override
public int size() {

    return this.lines.length;
}

@Override
public Iterator<Line> iterator() {

    return new ListIterator(this.lines);

}

@Override
public void push(Line newValue) {
    if (newValue == null) {
        throw new IllegalArgumentException("Item is null");
    }

    Line[] holder = new Line[this.size() + 1];
    for (int i = 0; i < this.size(); i++) {
        holder[i] = this.lines[i];
    }
    holder[this.size() + 1] = newValue;
    this.lines = new Line[this.size() + 1];
    this.lines = holder;

}

@Override
public Line peek() {

    return this.lines[this.lines.length];

}

@Override
public Line pop() {
    Line poppedVal = null;
    poppedVal = this.lines[this.size()];

    Line[] holder = new Line[this.size() - 1];

    for (int i = 0; i <= (this.size() - 1); i++) {
        holder[i] = this.lines[i];
    }
    this.lines = new Line[this.size() - 1];
    this.lines = holder;
    return poppedVal;

}

protected class ListIterator implements Iterator<Line> {
    private Line[] array;
    private int index = 0;
    private int size;

    public ListIterator(Line[] anArray) {
        array = anArray;
        size = array.length;
    }

    public boolean hasNext() {
        return (index + 1) >= size;
    }

    public Line next() {
        Line nextVal = this.array[size];
        return nextVal;

    }

    @Override
    public void remove() {
        throw new UnsupportedOperationException();

    }

}

}

我得到的错误是：holder[this.size() + 1] = newValue; this.lines.push(new Line(a, b));和Line nextVal = this.array[size]; Line lne = (Line) iter.next();

再次感谢。

Answer 1

这里，容器的大小是this.size() + 1

Line[] holder = new Line[this.size() + 1];

但是在这里，您尝试将值添加到size索引

holder[this.size() + 1] = newValue;

例如，如果size()返回5，那么holder的大小就是5。因此，最大索引将是4。但是您是在向holder5添加值；

我希望你能理解这种情况

因此，添加如下值

holder[this.size()] = newValue;