Hashmap in Java | Internal Working of Hashmap in Java | Hashmap Implementation | DSA-One Course #30 

thanx a lot bro, bohot bohot shukriya bhaijan,,,maine noten kr lia hai

woh jo table tha red me 9:57 woh bucket hai

Bucketing is nothing but index of that node Array Hashmap doesn't contain synchronized method or variable , that's y it is not thread safe, overcome to resolve this problem we are having HashTable (as it contains all synchronized method)

Great Amit. For people who are looking here for the answers - Buckets are basically the area that contains values. Loadfactor is the threshold for the percentage of the bucket when it is decided that now bucket is going to be full and then the capacity is doubled. By default, loadfactor is 75% and capacity is 16. Totally configurable via constructor. The reason a hashmap isn't recommended in a MT env because when multiple threads start to access the data while some thread is updating it, there can be issues. Whenever overriding equals, it is mandatory to override hashCode so that every time when equals is called, the values generated by hashCode remain consistent. Rest 4 and 6 are explanatory. Can be looked on internet. Easy stuff.

Bucketing in HashMap is the process of storing multiple values in a single location (bucket) of the internal array of the HashMap, which is indexed using a hash function. The hash function calculates the hash code of the key and uses it as an index in the array. If multiple keys have the same hash code, they are stored in the same bucket as linked nodes. Load factor is a measure of how full a HashMap is allowed to get before its capacity is automatically increased. It is a float value that ranges from 0.0 to 1.0. When the number of entries in the HashMap exceeds the load factor multiplied by the current capacity, the capacity is increased, and the entries are rehashed. HashMap is not recommended in a multi-threaded environment because it is not thread-safe. If multiple threads access a HashMap concurrently, it may result in an inconsistent state of the HashMap, leading to data loss or unexpected results. ConcurrentHashMap is recommended for use in a multi-threaded environment. Here's an example implementation of a HashMap using a custom class as a key: class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } // getters and setters @Override public int hashCode() { return Objects.hash(name, age); } @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Person)) return false; Person person = (Person) o; return age == person.age && Objects.equals(name, person.name); } } class CustomHashMap { private List[] buckets; private int capacity; private int size; private static class Entry { K key; V value; public Entry(K key, V value) { this.key = key; this.value = value; } // getters and setters } public CustomHashMap(int capacity) { this.buckets = new List[capacity]; this.capacity = capacity; this.size = 0; } public void put(K key, V value) { int index = key.hashCode() % capacity; if (buckets[index] == null) { buckets[index] = new LinkedList(); } for (Entry entry : buckets[index]) { if (entry.key.equals(key)) { entry.value = value; return; } } buckets[index].add(new Entry(key, value)); size++; } public V get(K key) { int index = key.hashCode() % capacity; if (buckets[index] == null) { return null; } for (Entry entry : buckets[index]) { if (entry.key.equals(key)) { return entry.value; } } return null; } public int size() { return size; } // other methods } It is highly recommended to override the equals() and hashCode() methods when using custom objects as keys in a HashMap. If these methods are not overridden, the default implementations in the Object class are used, which compares object references rather than object contents. This can lead to unexpected behavior, where two objects that are considered equal by their contents are not considered equal by the HashMap. As a result, the HashMap may not be able to retrieve the values correctly.

Thanks Anuj ♥️

You're welcome ☺️

Thanks

If it was really helpful, I will never stop making videos like this 🤗