Hazelcast Jet IMap删除条目

问题描述

我已经阅读了Hazelcast Jet的文档。

我已经看到可以在IMap接收器中添加/更新条目。 但是我从没见过从IMap删除条目的方法。

有办法吗？

解决方法

请参见来自JavaDoc的Sinks.mapWithMerging：

    /**
     * Returns a sink that uses the supplied functions to extract the key
     * and value with which to update a Hazelcast {@code IMap}. If the map
     * already contains the key,it applies the given {@code mergeFn} to
     * resolve the existing and the proposed value into the value to use. If
     * the value comes out as {@code null},it removes the key from the map.
     * Expressed as code,the sink performs the equivalent of the following for
     * each item:
     * <pre>
     * K key = toKeyFn.apply(item);
     * V oldValue = map.get(key);
     * V newValue = toValueFn.apply(item);
     * V resolved = (oldValue == null)
     *            ? newValue
                  : mergeFn.apply(oldValue,newValue);
     * if (value == null)
     *     map.remove(key);
     * else
     *     map.put(key,value);
     * </pre>
...