java - CacheBuilder.newBuilder().build 不明确

Question

我正在尝试使用 Stash 插件的代码片段，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 另一方面有一个 build() 方法，它需要 CacheLoader 作为参数。

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);
    }
}); 

这应该有效。

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