Java - How to create new Entry (key, value)

To create a new key-value pair in a Map in Java, you can use the put method. For example:

Map<String, Integer> map = new HashMap<>();
map.put("apple", 5);
map.put("banana", 3);

This creates a new HashMap and adds two key-value pairs to it: ("apple", 5) and ("banana", 3).

You can also use the putIfAbsent method to add a new key-value pair to the map only if the key is not already present in the map. For example:

map.putIfAbsent("apple", 10);  // does not add a new pair because "apple" is already a key in the map
map.putIfAbsent("orange", 10);  // adds a new pair ("orange", 10)

You can also use the putAll method to add all the key-value pairs from another map to the map:

Map<String, Integer> map2 = new HashMap<>();
map2.put("mango", 2);
map2.put("grape", 4);

map.putAll(map2);  // adds all pairs from map2 to map