Menu
Map doesn't allow duplicate keys, but it allows duplicate values. HashMap and LinkedHashMap allows null keys and null values but TreeMap doesn't allow any null key or value.
Map does not supports duplicate keys. you can use collection as value against same key. Because if the map previously contained a mapping for the key, the old value is replaced by the specified value.
HashMap is a non-synchronized class of the Java Collection Framework that contains null values and keys, whereas Map is a Java interface, which is used to map key-pair values.
Map<String, List<String>> map = new HashMap<>(); List<String> list = new ArrayList<>(); map. put("key1", list); map. get("key1"). add("value1"); map.
Map is an interface, i.e. an abstract "thing" that defines how something can be used. HashMap is an implementation of that interface.
Map<K,V> is an interface,
HashMap<K,V> is a class that implements Map.
you can do
Map<Key,Value> map = new HashMap<Key,Value>();
Here you have a link to the documentation of each one: Map, HashMap.
Map is an interface; HashMap is a particular implementation of that interface.
HashMap uses a collection of hashed key values to do its lookup. TreeMap will use a red-black tree as its underlying data store.
Map is an interface in Java. And HashMap is an implementation of that interface (i.e. provides all of the methods specified in the interface).
HashMap is an implementation of Map. Map is just an interface for any type of map.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With