JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: How to get all keys from TreeMap?


Description:

Below example shows how to get all keys from the given TreeMap. By using keySet() method, you can get all key entries as a Set object.


Code:
package com.java2novice.treemap;

import java.util.Set;
import java.util.TreeMap;

public class MyTreeMapKeys {

	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);
		Set<String> keys = hm.keySet();
		for(String key: keys){
			System.out.println(key);
		}
	}
}

Output:
{first=FIRST INSERTED, second=SECOND INSERTED, third=THIRD INSERTED}
first
second
third
<< Previous Program | 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?
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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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