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JAVA EXAMPLE PROGRAMS

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Program: How to get all keys from Hashtable?


Description:

Below example shows how to get list of keys. keySet() method returns Set object will all keys.


Code:
package com.java2novice.hashtable;

import java.util.Hashtable;
import java.util.Set;

public class MyHashtableKeys {

	public static void main(String a[]){
		Hashtable<String, String> hm = new Hashtable<String, String>();
		//add key-value pair to Hashtable
		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:
{third=THIRD INSERTED, second=SECOND INSERTED, first=FIRST INSERTED}
third
second
first
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List Of All Hashtable Sample Programs:

  1. Basic Hashtable Operations.
  2. How to iterate through Hashtable?
  3. How to copy Map content to another Hashtable?
  4. How to search a key in Hashtable?
  5. How to search a value in Hashtable?
  6. How to get all keys from Hashtable?
  7. How to get entry set from Hashtable?
  8. How to delete all elements from Hashtable?
  9. How to read elements using Enumeration in Hashtable?
  10. Hashtable implementation with equals and hashcode example.
  11. How to fetch values with user define object as keys in Hashtable?
  12. How to eliminate duplicate keys (user defined objects) with Hashtable?
Knowledge Centre
String Vs StringBuffer
We know that String is immutable object. We can not change the value of a String object once it is initiated. If we try to change the value of the existing String object then it creates new object rather than changing the value of the existing object. So incase, we are going to do more modificatios on String, then use StringBuffer. StringBuffer updates the existing objects value, rather creating new object.
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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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