TreeMap implementation in java

              A TreeMap is a category in Map interface. To implement this in java, an interface “NavigableMap” is used. It also stores the key, value pair in a natural order or any specified order.

TreeMap has some specific features are listed below….

• ·       It accept only null values,not the null keys.
• ·       The ordering of entries may be in natural order or any order provided by the comparator.
• ·       It follows Red-Black Tree for internal implementation.

How to implement TreeMap in java?

• It includes builtin packages in java(java.util.Map,java.util.TreeMap).
• A public class TreeMapEg is created with main function().
• An object instance is created for TreeMap.
• To add the key, value pair, a builtin function put() is used.
• Get() function is used to find the given key in the treeMap and gives you the key value pair.
• containsKey() checks the key in the treeMap.
• getValue(),getKey() is used to get the value and key.
• Remove() is used to delete the key,value.
• Clear () clears all the values in treeMap.
• isEmpty() returns a Boolean value.

Program:

import java.util.Map;

import java.util.TreeMap;

public class TreeMapEg {

    public static void main(String[] args) {

        // Let us create a TreeMap

        Map<String, Integer> treeMap1 = new TreeMap<>();

        // inserting  values for key-value pairs

        treeMap1.put("Onion", 500);

        treeMap1.put("Carrot", 200);

        treeMap1.put("Brinjal", 300);

        treeMap1.put("Tomato", 400);

        treeMap1.put("Potato",350);

        treeMap1.put("Cabbage",500);

        // Search and retrieve a key,value pair

        System.out.println("Weight of the Tomato: " + treeMap1.get("Tomato"));

        // Check for a key

        if (treeMap1.containsKey("Brinjal")) {

            System.out.println("Brinjal is available.");

        }

         System.out.println("The list of vegetables and its price:");

        //Loop to print the value,key pair

        for (Map.Entry<String, Integer> entry : treeMap1.entrySet()) {

            System.out.println(entry.getKey() + ": " + entry.getValue());

        }

         // Remove a pair

        treeMap1.remove("Cabbage");

         // Here, the size of TreeMap is displayed

        System.out.println("Size of the TreeMap: " + treeMap1.size());

         // Clear the contents in the TreeMap

        treeMap1.clear();

         //Check the treeMap emptiness

        if(treeMap1.isEmpty())

        System.out.println("The TreeMap is empty");

    }

}

Output:

C:\raji\blog>javac TreeMapEg.java

C:\raji\blog>java TreeMapEg

Weight of the Tomato: 400

Brinjal is available.

The list of vegetables and its price:

Brinjal: 300

Cabbage: 500

Carrot: 200

Onion: 500

Potato: 350

Tomato: 400

Size of the TreeMap: 5

The TreeMap is empty

This is the simple way of implementing TreeMap in java. If you have  any queries, post in the comment.Keep coding!!!!