Read Also : How HashSet works internally in Java In line 15, the removed Entry object is returned to the remove(key) method. In line 14, recordRemoval() method is called on the desired Entry object whenever the Entry is removed from the table. In line 10, (prev=e) condition will be trueĮlse bucket has more than one Entry object If bucket has single Entry object, then, Then two cases arises, whether bucket has single Entry object or it has more than one Entry object , In line 7, If condition is true then we get the desired Entry object which we need to remove from the hashmap object. One by one and comparing the hashValue and key of each Entry object. We need to iterate through the bucket and its index
To check if we get the desired Entry object ,we need hashValue, key andīucketindex. In line 5, We iterate thorugh the Entry starting from the e ,till we get the desired Entry object In line 4, We created an Entry instance variable e which holds the prev value ,i.e, the first entry in the appropriate bucket.īelow Explanation is about removing a single object from the simple LinkedList that is removing the desired Entry object from the LinkedList Here table is an array of Entry objects i.e Entry table. In line 3, we start traversing from the first entry in the bucket ,till we get the desired Entry object, previs used to store the first entry in the bucket. So we get the first entry of the desired bucket. In line 2, indexFor(int,int), for the given hashValue, returns the first entry in the appropriate bucket. We have hashValue and key, now we need to find the bucketindex of the desired Entry object
To defend against poor quality hash functions, we are calculating the hashValue again using hash(hashValue) in the above line. We are now applying returned hashvalue into its own hashfunction. In the line 1 of removeEntryForKey(key), if the key passed as a parameter is not null then, it will call hashfunction on the key object, so after key.hashCode() returns hashValue, so line 1 will look like Interviewer : Explain the removeEntryForKey(key) method in HashMap in detail, considering key is not null? Thus null is returned to the remove(key) method, which will in turn return null. In line 5, while loop condition returns false In line 2, the value of indexFor will return 0 thus i=0. The following lines will be executed in the removeEntryForKey(key) method Interviewer: What happens if the null key is passed in the remove(key) method ? Worst Case time complexity of remove(key) : O(n) Interviewer : What is the time complexity of performing remove operation in HashMap using remove(key)īest Case time complexity of remove(key) : O(1) Since LinkedHashMap extends HashMap, thus this method is overridden in the LinkedHashMap's Entry in order to maintain its linked list of entries. It is invoked whenever the Entry is removed from the table. RecordRemoval() method is a concrete method without any body. This effectively reduces the container size by the number of. Interviewer : What is the purpose of calling recordRemoval() method in the removeEntryForKey(key) since it is the concrete method without any body. Removes from the map container either a single element or a range of elements (first,last)). In sorted maps, the positions of new elements are defined by the order of their keys.Public class JavaHungry When a new entry is put into a LinkedHashMap (the default map implementation), it is added so that it comes last when iterating the map. To add a new key-value pair to a mutable map, use put(). You can add and remove whole entries.īelow are descriptions of the standard library functions for write operations available on mutable maps.
In turn, keys never change: once you add an entry, its key is constant.įor each key, there is always a single value associated with it. There are certain rules that define write operations on maps: These operations let you change the map content using the key-based access to the values. Return Value: The method returns the value that was previously mapped to the specified key if the key exists else the method returns NULL. Returns the value associated with key before it was removed. Syntax: TreeMap.remove ( Object key) Parameters: The method takes one parameter key whose mapping is to be removed from the Map. Mutable maps offer map-specific write operations. Removes key and its associated value, if present, from the map. Println(numbersMap - listOf("two", "four"))įor details on using plusAssign ( +=) and minusAssign ( -=) operators on mutable maps, see Map write operations below. Val numbersMap = mapOf("one" to 1, "two" to 2, "three" to 3)
0 kommentar(er)
