# Class: com.pnfsoftware.jeb.util.collect.MultiMap A map of keys to lists, whose insertion order for the values of a given key is maintained. This class is [serializable](Ser). Null key is allowed except for natural ordering; null values are allowed. Thread\-safety: none. Note: this class does not implement the [Map](Map) interface, but attempts to follow its guidelines and contracts the best it can. One notable exception is that this class does not override hashCode/equals. ## Constructor: MultiMap Description: Create a new multi\-map. ## Constructor: MultiMap - parameter: `keyOrder`, type: `com.pnfsoftware.jeb.util.collect.CollectionOrder` Description: Create a new multi\-map. parameter: keyOrder: key ordering ## Method: clear Description: Remove all key\-value mappings. ## Method: containsKey - parameter: `key`, type: `K` - return type: `boolean` Description: Determine whether this multi\-map contains a key. parameter: key: key return: true if the key is present ## Method: containsValue - parameter: `value`, type: `V` - return type: `boolean` Description: Determine whether this multi\-map contains a value. parameter: value: value return: true if any key maps to the value ## Method: createKey - parameter: `key`, type: `K` - return type: `boolean` Description: Create an explicit entry for a given key. If no values mapped by the given key previously existed, the associated value will be an empty collection. parameter: key: key return: true if the map did not already contain the key; false otherwise \(the key entry existed before\) ## Method: get - parameter: `key`, type: `K` - parameter: `safe`, type: `boolean` - return type: `java.util.List` Description: Retrieve the list of values associated with the provided key. parameter: key: a key parameter: safe: if true, an empty list of values is returned if the key does not exist return: a list, possibly null or empty \(depending on the `safe` parameter} ## Method: get - parameter: `key`, type: `K` - return type: `java.util.List` Description: Retrieve the list of values associated with the provided key. Same as [get\(key, safe=false\)](#get(Object, boolean)). parameter: key: a key return: a list, possibly null if nothing was `put` for the provided key ## Method: getSafe - parameter: `key`, type: `K` - return type: `java.util.List` Description: Retrieve the list of values associated with the provided key. Same as [get\(key, safe=true\)](#get(Object, boolean)). parameter: key: key return: a non\-null list of values ## Method: isEmpty - return type: `boolean` Description: Determine whether this multi\-map has no values. return: true if no values are mapped ## Method: keySet - return type: `java.util.Set` Description: Retrieve a read\-only view of the keys. WARNING: This method does not respect the [Map#keySet()](Map#keySet()) contract: the set returned is read\-only. return: read\-only view of the key set ## Method: keySize - return type: `int` Description: Get the number of keys in this multi\-map. return: number of keys, including keys mapped to empty value lists ## Method: put - parameter: `key`, type: `K` - parameter: `value`, type: `V` - return type: `int` Description: Add a key\-value mapping. parameter: key: key parameter: value: value return: updated count of values associated with the key ## Method: putAll - parameter: `m`, type: `java.util.Map>` Description: Add all mappings from a map of keys to lists of values. parameter: m: map of values to add ## Method: putMulti - parameter: `key`, type: `K` - parameter: `values`, type: `java.util.Collection` Description: Add multiple elements mapped by the same key. Note that if an empty collection is provided, the entry for the provided key will not be be explicitly created. parameter: key: key parameter: values: values to add ## Method: remove - parameter: `key`, type: `K` - return type: `java.util.List` Description: Remove all values associated with a key. parameter: key: key return: removed values, or null if the key was absent ## Method: removeAll - parameter: `keys`, type: `java.util.Collection` - return type: `boolean` Description: Remove all entries mapping to the collection of keys. Similar semantics as [Set#removeAll(Collection)](Set#removeAll(Collection)). parameter: keys: keys to remove return: true if the multi\-map was modified ## Method: removeMulti - parameter: `key`, type: `K` - parameter: `values`, type: `java.util.Collection` - return type: `int` Description: Remove multiple values associated with a key. parameter: key: key parameter: values: values to remove return: number of removed values ## Method: removeMulti - parameter: `key`, type: `K` - parameter: `values`, type: `java.util.Collection` - parameter: `removeEmptyBucket`, type: `boolean` - return type: `int` Description: Remove multiple values associated with a key. parameter: key: key parameter: values: values to remove parameter: removeEmptyBucket: true to remove the key if its value list becomes empty return: number of removed values ## Method: removeValue - parameter: `key`, type: `K` - parameter: `value`, type: `V` - return type: `V` Description: Remove a value associated with a key. parameter: key: key parameter: value: value to remove return: removed value, or null if no value was removed ## Method: removeValue - parameter: `key`, type: `K` - parameter: `value`, type: `V` - parameter: `removeEmptyBucket`, type: `boolean` - return type: `V` Description: Remove a value associated with a key. parameter: key: key parameter: value: value to remove parameter: removeEmptyBucket: true to remove the key if its value list becomes empty return: removed value, or null if no value was removed ## Method: size - return type: `int` Description: Get the number of key\-value mappings \(per Map interface\). That is, the number of values. return: number of values ## Method: toString - return type: `java.lang.String` ## Method: values - return type: `java.util.Collection` Description: Retrieve all values. return: read\-only collection of values