JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: Basic TreeMap Operations.


Description:

Below example shows basic operations on TreeMap like creating an object, adding key-value pair objects, gtting value by passing key object, checking whether the map has elements or not, deleting specific entry, and size of the TreeMap.


Code:
package com.java2novice.treemap;

import java.util.TreeMap;

public class MyBasicOperations {
	
	public static void main(String a[]){
		TreeMap<String, String> hm = new TreeMap<String, String>();
		//add key-value pair to TreeMap
		hm.put("first", "FIRST INSERTED");
		hm.put("second", "SECOND INSERTED");
		hm.put("third","THIRD INSERTED");
		System.out.println(hm);
		//getting value for the given key from TreeMap
		System.out.println("Value of second: "+hm.get("second"));
		System.out.println("Is TreeMap empty? "+hm.isEmpty());
		hm.remove("third");
		System.out.println(hm);
		System.out.println("Size of the TreeMap: "+hm.size());
	}
}

Output:
{first=FIRST INSERTED, second=SECOND INSERTED, third=THIRD INSERTED}
Value of second: SECOND INSERTED
Is TreeMap empty? false
{first=FIRST INSERTED, second=SECOND INSERTED}
Size of the TreeMap: 2
Next Program >>

List Of All TreeMap Sample Programs:

  1. Basic TreeMap Operations.
  2. How to iterate through TreeMap?
  3. How to copy Map content to another TreeMap?
  4. How to search a key in TreeMap?
  5. How to search a value in TreeMap?
  6. How to get all keys from TreeMap?
  7. How to get entry set from TreeMap?
  8. How to delete all elements from TreeMap?
  9. How to sort keys in TreeMap by using Comparator?
  10. How to sort keys in TreeMap by using Comparator with user define objects?
  11. How to get sorted sub-map from TreeMap?
  12. How to get first key element from TreeMap (Sorted Map)?
  13. How to get last key element from TreeMap (Sorted Map)?
  14. How to reverse sorted keys in a TreeMap?
Knowledge Centre
Different types of Access Modifiers
public: Any thing declared as public can be accessed from anywhere.

private: Any thing declared as private can't be seen outside of its class.

protected: Any thing declared as protected can be accessed by classes in the same package and subclasses in the other packages.

default modifier: Can be accessed only to classes in the same package.
Famous Quotations
The greatest obstacle to discovery is not ignorance; it is the illusion of knowledge.
-- Daniel J. Boorstin

About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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