怎么判断map集合里的list集合的size

如题我想map里存入了有object有key-value还有key-value（list集合的）现在我想判断出list集合的size怎么判断呢

<span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title function_">main</span>(<span class="hljs-built_in">String</span>[] args) {
        Map<<span class="hljs-built_in">String</span>, <span class="hljs-built_in">Object</span>> <span class="hljs-built_in">map</span> = <span class="hljs-keyword">new </span><span class="hljs-class title_">HashMap</span><>();
        <span class="hljs-built_in">map</span>.<span class="hljs-property">put</span>(<span class="hljs-string">"a"</span>, <span class="hljs-keyword">new </span><span class="hljs-class title_">ArrayList</span>(<span class="hljs-number">1</span>) {{
            <span class="hljs-built_in">add</span>(<span class="hljs-string">"a"</span>);
        }});
        <span class="hljs-built_in">map</span>.<span class="hljs-property">values</span>().<span class="hljs-property">forEach</span>(item -> {
            System.<span class="hljs-property">out</span>.<span class="hljs-property">println</span>(((<span class="hljs-built_in">ArrayList</span><<span class="hljs-built_in">Object</span>>) item).<span class="hljs-property">size</span>());
        });
    }

运行结果：

map里有数据了吗，有的话遍历map，列出来所有key对应的value，已经知道value是list了，直接list.size()就完了，如果有类型转化的话按照提示转一下就可以了

你说啥那