PriorityQueue.toString错误的元素顺序 [英] PriorityQueue.toString wrong element order

问题描述

我正在尝试使用优先级最低的节点在java中创建优先级队列。但是，我的比较器不工作，输出非常奇怪。我相信我需要改变我的比较器，但我不知道如何改变它。
这是我的代码：

I am trying to make a priority queue in java with the nodes with the lowest frequency in priority. However, my comparator is not working and the output is very weird. I believe I need to change my comparator but I am not sure how to change it. Here is my code:

public class HuffmanComparator implements Comparator<TreeNodeHuffman> {
    public int compare(TreeNodeHuffman p1, TreeNodeHuffman p2) {
        if (p1.frequency < p2.frequency) return -1;
        if (p1.frequency > p2.frequency) return 1;
        return 0;
    }    
}

public class TreeNodeHuffman {
public static void main(String[] args) {    
    HuffmanComparator compare = new HuffmanComparator();
    TreeNodeHuffman e = new TreeNodeHuffman('e', 12702);
    TreeNodeHuffman t = new TreeNodeHuffman('t', 9056);
    TreeNodeHuffman a = new TreeNodeHuffman('a', 8167);
    TreeNodeHuffman o = new TreeNodeHuffman('o', 7507);
    TreeNodeHuffman i = new TreeNodeHuffman('i', 6966);
    TreeNodeHuffman n = new TreeNodeHuffman('a', 6749);
    TreeNodeHuffman s = new TreeNodeHuffman('s', 6327);
    TreeNodeHuffman h = new TreeNodeHuffman('h', 6094);
    TreeNodeHuffman r = new TreeNodeHuffman('r', 5987);
    TreeNodeHuffman d = new TreeNodeHuffman('d', 4253);
    TreeNodeHuffman l = new TreeNodeHuffman('l', 4025);
    TreeNodeHuffman c = new TreeNodeHuffman('c', 2782);
    TreeNodeHuffman u = new TreeNodeHuffman('u', 2758);
    TreeNodeHuffman m = new TreeNodeHuffman('m', 2406);
    TreeNodeHuffman w = new TreeNodeHuffman('w', 2360);
    TreeNodeHuffman f = new TreeNodeHuffman('f', 2228);
    TreeNodeHuffman g = new TreeNodeHuffman('g', 2015);
    TreeNodeHuffman y = new TreeNodeHuffman('y', 1974);
    TreeNodeHuffman p = new TreeNodeHuffman('p', 1929);
    TreeNodeHuffman b = new TreeNodeHuffman('b', 1492);
    TreeNodeHuffman v = new TreeNodeHuffman('v', 978);
    TreeNodeHuffman k = new TreeNodeHuffman('k', 772);
    TreeNodeHuffman j = new TreeNodeHuffman('j', 153);
    TreeNodeHuffman x = new TreeNodeHuffman('x', 150);
    TreeNodeHuffman q = new TreeNodeHuffman('q', 95);
    TreeNodeHuffman z = new TreeNodeHuffman('z', 74);
    PriorityQueue<TreeNodeHuffman> queue = new PriorityQueue<TreeNodeHuffman>(26, compare);
    queue.add(e);
    queue.add(t);
    queue.add(a);
    queue.add(o);
    queue.add(i);
    queue.add(n);
    queue.add(s);
    queue.add(h);
    queue.add(r);
    queue.add(d);
    queue.add(l);
    queue.add(c);
    queue.add(u);
    queue.add(m);
    queue.add(w);
    queue.add(f);
    queue.add(g);
    queue.add(y);
    queue.add(p);
    queue.add(b);
    queue.add(v);
    queue.add(k);
    queue.add(j);
    queue.add(x);
    queue.add(q);
    queue.add(z);
    System.out.println(queue);
}
}

输出如下：
[ z，k，q，g，v，x，u，d，f，y，b，m，j，i，c，e，s，o，w，a，r，h，p，t，l，一个]。
但是，输出应该是[z，q，x，j，k，v，b ........]。
提前致谢！

The output is as follows: [z, k, q, g, v, x, u, d, f, y, b, m, j, i, c, e, s, o, w, a, r, h, p, t, l, a]. However, the output should be [z, q, x, j, k, v, b........]. Thanks in advance!

推荐答案

您需要轮询 PriorityQueue中的项目一个接一个。 toString 不会这样做。

You need to poll the items from the PriorityQueue one by one. toString doesn't do that.

所以而不是你的 System.out.println （队列）; 执行此操作：

So instead of your System.out.println(queue); do this:

while(!queue.isEmpty()) {
   System.out.println(queue.poll());
}

原因是 PriorityQueue 永远不会在内部完全排序，查找堆如何工作以获取更多细节。从中调查项目会在调用期间修复堆，因此它应该按排序顺序输出元素。

The reason is that the PriorityQueue is never completely sorted internally, lookup how a heap works for more detail. Polling items from it fixes the heap during the calls, thus it should output the elements in sorted order.

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