Have been processed or the action throws an exception. Performs the given action for each entry in this map until all entries Throws: - if the put operation is not supported by this map (optional) If the value for the specified key is present and non-null, attempts to Rethrown, and the current mapping is left unchanged. If theįunction itself throws an (unchecked) exception, the exception is If the function returns null, the mapping is removed. If the value for the specified key is present and non-null, attempts toĬompute a new mapping given the key and its current mapped value. The specified key, or null if the computed value is null - `default V` Mapping-function - the function to compute a value - `` Throws: - if the put operation is not supported by this map (optional) If the specified key is not already associated with a value (or is mapped The specified key, or null if the computed value is null - default V Returns: the current (existing or computed) value associated with Mapping-function - the function to compute a value. Map.computeIfAbsent(key, k -> new HashSet()).add(v) Map.computeIfAbsent(key, k -> new Value(f(k))) The mostĬommon usage is to construct a new object serving as an initial The function itself throws an (unchecked) exception, theĮxception is rethrown, and no mapping is recorded. If the function returns null no mapping is recorded. To null), attempts to compute its value using the given mappingįunction and enters it into this map unless null. If the specified key is not already associated with a value (or is mapped Throws: - if the put operation is not supported by this map (optional) raw docstring Returns: the new value associated with the specified key, or null if none - `default V` Remapping-function - the function to compute a value - `` Key - key with which the specified value is to be associated - `K` Throws: - if the put operation is not supported by this map (optional) Attempts to compute a mapping for the specified key and its current Returns: the new value associated with the specified key, or null if none - default V Remapping-function - the function to compute a value. Key - key with which the specified value is to be associated - K (unchecked) exception, the exception is rethrown, and the current mapping If the function returns null, the mapping is removed (or (Method merge() is often simpler to use for such purposes.) Map.compute(key, (k, v) -> (v = null) ? msg : v.concat(msg)) ForĮxample, to either create or append a String msg to a value Mapped value (or null if there is no current mapping). Attempts to compute a mapping for the specified key and its current
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