CacheBuilder.newBuilder().build is ambiguous

Question

我正试图为Stash插件使用一段代码，但编译器一直给我一个我似乎无法解决的错误。它使用com.google.common.cache.cache（Guava）

 static final RepositorySettings DEFAULT_SETTINGS = new RepositorySettings(0);
 private final PluginSettings pluginSettings;
 private final Cache<Integer, RepositorySettings> cache = CacheBuilder.newBuilder().build(
        new CacheLoader<Integer, RepositorySettings>()
 {
    @Override
    public RepositorySettings load(@Nonnull Integer repositoryId)
    {
        @SuppressWarnings("unchecked")
        Map<String, String> data = (Map) pluginSettings.get(repositoryId.toString());
        return data == null ? DEFAULT_SETTINGS : deserialize(data);
    }
});

.build给了我以下错误

The method build(CacheLoader<? super Integer,RepositorySettings>) is ambiguous for the type CacheBuilder<Object,Object>

Answer 1

Cache有一个不带参数的build()方法，而LoadingCache有一个以CacheLoader为参数的build()方法。

private final LoadingCache<Integer, RepositorySettings> cache = CacheBuilder.newBuilder().build(
                      new CacheLoader<Integer, RepositorySettings>() {
    @Override
    public RepositorySettings load(@Nonnull Integer repositoryId) {
    @SuppressWarnings("unchecked")
    Map<String, String> data = (Map) pluginSettings.get(repositoryId.toString());
    return data == null ? DEFAULT_SETTINGS : deserialize(data);
    }
}); 

这应该行得通。

作为参考：http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/cache/CacheBuilder.html