Collection Examples,Tree Maps,TreeMap Example,TreeMap Example Java,Java TreeMap,Java TreeMap Example

Tree Map Example

In the following example, we have used the TreeMap method, which stores its elements in a tree and orders its elements based on their values. Here in the example we have used the key of the element to show the values of the element. To retrieve the keys and values use keySet() and values() method respectively.

This program shows the data elements left after removing the particular element by specifying its key. Using the Iterator interface methods, we can traverse a collection from start to finish and safely remove elements from the underlying Collection.

Here is the code of program:


import java.util.*;



public class TreeMapExample{

  public static void main(String[] args) {

    System.out.println("Tree Map Example!\n");

    TreeMap <Integer, String>tMap = new TreeMap<Integer, String>();

    //Addding data to a tree map

    tMap.put(1, "Sunday");

    tMap.put(2, "Monday");

    tMap.put(3, "Tuesday");

    tMap.put(4, "Wednesday");

    tMap.put(5, "Thursday");

    tMap.put(6, "Friday");

    tMap.put(7, "Saturday");

    //Rerieving all keys

    System.out.println("Keys of tree map: " + tMap.keySet());

    //Rerieving all values

    System.out.println("Values of tree map: " + tMap.values());

    //Rerieving the value from key with key number 5

    System.out.println("Key: 5 value: " + tMap.get(5)+ "\n");

    //Rerieving the First key and its value

    System.out.println("First key: " + tMap.firstKey() + " Value: " 

                                    
+ tMap.get(tMap.firstKey()) + "\n");

    //Rerieving the Last key and value

    System.out.println("Last key: " + tMap.lastKey() + " Value: " 

                                       
+ tMap.get(tMap.lastKey()) + "\n");

    //Removing the first key and value

    System.out.println("Removing first data: " + tMap.remove(tMap.firstKey()));

    System.out.println("Now the tree map Keys: " + tMap.keySet());

    System.out.println("Now the tree map contain: " + tMap.values() + "\n");

    //Removing the last key and value

    System.out.println("Removing last data: " + tMap.remove(tMap.lastKey()));

    System.out.println("Now the tree map Keys: " + tMap.keySet());

    System.out.println("Now the tree map contain: " + tMap.values());

  }

}

Output of this program:

C:\vinod\collection>javac TreeMapExample.java

C:\vinod\collection>java TreeMapExample
Tree Map Example!

Keys of tree map: [1, 2, 3, 4, 5, 6, 7]
Values of tree map: [Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday]
Key: 5 value: Thursday

First key: 1 Value: Sunday

Last key: 7 Value: Saturday

Removing first data: Sunday
Now the tree map Keys: [2, 3, 4, 5, 6, 7]
Now the tree map contain: [Monday, Tuesday, Wednesday, Thursday, Friday, Saturday]

Removing last data: Saturday
Now the tree map Keys: [2, 3, 4, 5, 6]
Now the tree map contain: [Monday, Tuesday, Wednesday, Thursday, Friday]

C:\vinod\collection>