您如何序列化番石榴集合？ [英] How do you serialize a guava collection?

问题描述

我肯定缺少明显的东西，但是我无法序列化 TreeBasedTable 。它被标记为 @GwtCompatible（serializable = true），所以我的理解是我需要使用 guava-gwt

I must be missing something obvious but I can't manage to serialize a TreeBasedTable. It is marked as @GwtCompatible(serializable = true), so my understanding is that I need to use the guava-gwt library to (de-)serialize it.

但我找不到这样做。

有关信息，我的pom包含番石榴和 guava-gwt ，均为14.0版。

For information, my pom contains guava and guava-gwt, both version 14.0.

编辑

因此，感谢您的回答，我现在知道TreeBasedTable是可序列化的。因此，我删除了所有gwt引用并使其正常工作。但是，此代码仍然失败（这是使我认为TreeBasedTable无法序列化的代码）-所以我想问题出在自定义比较器...

So thanks to the answer, I now understand that TreeBasedTable is serializable. So I have removed all the gwt references and got it to work. However, this code still fails (which is the code that made me think that TreeBasedTable was not serializable) - so I guess the problem is with the custom Comparators...

public static void main(String[] args) throws Exception {
    //with the following table it works
    //Table<Integer, String, Object> table = TreeBasedTable.create();

    //but with this one, it fails
    Table<Integer, String, Object> table = TreeBasedTable.create(new Comparator<Integer>() {
        @Override
        public int compare(Integer o1, Integer o2) {
            return o1.compareTo(o2);
        }
    }, String.CASE_INSENSITIVE_ORDER);

    table.put(1, "s", 123);

    try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(Paths.get("c:/temp/test").
            toFile()));) {
        oos.writeObject(table);
    }

    Table<Integer, String, Object> saved = null;

    try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(Paths.get("c:/temp/test").
            toFile()));) {
        saved = (Table<Integer, String, Object>) ois.readObject();
    }

    System.out.println(table.equals(saved));
    Files.delete(Paths.get("C:/temp/test"));
}

推荐答案

是Java序列化，是的： TreeBasedTable 是 Serializable 。

If you are talking about plain Java serialization, yes: TreeBasedTable is Serializable.

TreeBasedTable 扩展了 StandardRowSortedTable ，扩展了 StandardTable ，其实现了可序列化。

TreeBasedTable extends StandardRowSortedTable which extends StandardTable which implements Serializable.

顺便说一句：简单的支票可以帮助您：

BTW: a simple check would have helped you:

Serializable foo = TreeBasedTable.create();

由于编译器没有抱怨这一行，因此您知道 TreeBasedTable 实现可序列化。

Since the compiler doesn't complain about this line, you know that TreeBasedTable implements Serializable.

更新：

String.CASE_INSENSITIVE_ORDER 实现可序列化，因此您所需要做的就是将匿名Integer比较器重构为实现 Serializable 的内部类。或者：更好，使用 Ordering.natural（） ，它已经是可序列化。

String.CASE_INSENSITIVE_ORDER implements Serializable, so all you need to do is to refactor your anonymous Integer comparator into an inner class that implements Serializable. Or: better yet, use Ordering.natural() instead, which is Serializable already.

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