首页 \ 问答 \ Java中是否存在弱/软双向映射?(Is there a weak/soft bidirectional Map in Java?)

Java中是否存在弱/软双向映射?(Is there a weak/soft bidirectional Map in Java?)

我想要一个“符号字母表”来获得带有弱/软引用的双向映射。 类似于Apache的Common BidiMap (或Guava的BiMap ),具有WeakMap的界面。

一个解决方案是使用BiMap<WeakReference<K>,V>和偶尔清理条目,但它不是最佳的。 有什么建议么?


I would like a "symbol alphabet" to have a bi-directional map with weak/soft references. Something like an Apache's Common BidiMap (or Guava's BiMap) with a WeakMap-like interface.

A solution would be to use BiMap<WeakReference<K>,V> and once in a while clean-up entries, but it's not optimal. Any suggestions?


原文:https://stackoverflow.com/questions/14011082
更新时间:2023-11-13 11:11

最满意答案

这可能不是最好的办法,但它对我有效。

您可能会发现这有帮助: http : //www.vogella.com/tutorials/JavaSerialization/article.html

我不得不在一些项目中也这样做。 这就是我做的:

public final class cacheThis {
private cacheThis() {}

public static void writeObject(Context context, String fileName, Object object) throws IOException {
      FileOutputStream fos = context.openFileOutput(fileName, Context.MODE_PRIVATE);
      ObjectOutputStream oos = new ObjectOutputStream(fos);
      oos.writeObject(object);
      oos.flush();
      oos.close();

      fos.close();
   }

   public static Object readObject(Context context, String fileName) throws IOException,
         ClassNotFoundException {
      FileInputStream fis = context.openFileInput(fileName);
      ObjectInputStream ois = new ObjectInputStream(fis);
      Object object = ois.readObject();
      fis.close();
      return object;
   }
}

要写入文件:

cacheThis.writeObject(YourActivity.this, fileName, movieList);

从文件读取:

movieList.addAll((List<Movie>) cacheThis.readObject(
                VideoActivity.this, fileName));

你必须让你的Movie类implements Serializable


This probably isn't the best way to do it, but it worked for me.

You might find this helpful: http://www.vogella.com/tutorials/JavaSerialization/article.html

I had to do the same in some project. This is what I did:

public final class cacheThis {
private cacheThis() {}

public static void writeObject(Context context, String fileName, Object object) throws IOException {
      FileOutputStream fos = context.openFileOutput(fileName, Context.MODE_PRIVATE);
      ObjectOutputStream oos = new ObjectOutputStream(fos);
      oos.writeObject(object);
      oos.flush();
      oos.close();

      fos.close();
   }

   public static Object readObject(Context context, String fileName) throws IOException,
         ClassNotFoundException {
      FileInputStream fis = context.openFileInput(fileName);
      ObjectInputStream ois = new ObjectInputStream(fis);
      Object object = ois.readObject();
      fis.close();
      return object;
   }
}

To write to file:

cacheThis.writeObject(YourActivity.this, fileName, movieList);

To read from file:

movieList.addAll((List<Movie>) cacheThis.readObject(
                VideoActivity.this, fileName));

You have to have your Movie class implements Serializable

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