Skip to main content

What is Hash Function and HashCode

Many a times you hear this term call hash function or hashcode. One of the most common usage is in Java when  discussing about Hashset or HashMap. Lets understand what is Hashcode and HashFunction.

What is Hash Function? 

A hash function is any function that can be used to map data of arbitrary size to data of fixed size -wikipediea 

In simple terms, think of hash function as a juicer where you can put any fruit and the result is always a juice. As the juicer is one way that is once you make the juice out of a fruit you cannot reverse the propose i.e. you cannot get the fruit back out of the juice. The same thing goes with the hash function once you get the resultant value you cannot reverse it. This is very important in information security and some people use this to store passwords ( they are other better ways to store passwords like salt technique but we wont discuss this in this post). 




What is HashCode

Hash code is the resultant of the hash function (its the final juice that comes out of the juicer). The length of hashcode is fixed (same like the juicer you always wanted a cup full of juice).  Hashcode is used to validate of two results are same or different. 

In Java, hashcode is used in hashset and hashmap.  

Comments

Post a Comment

Popular posts from this blog

Adding loading spinner to JSP Page using pure CSS and JS

I wanted to add loading spinner to the web application that I was working on. This application is a legacy application and I was looking into a way to add the loading spinner whenever the user performs certain actions such as the following Clicks a button which behind the scene performs CRUD operation When user request data  As the web application was based of JSP and I was looking for a way to adding it to the webpage and finally came across the following solution  Create a div  Add the CSS for the div Create a JS function which gets called on button click.  Here is the code HTML JS      CSS
3 comments
Read more

Enabling TLS 1.2 in Java 7

I am working on web application that uses third party API and apparently those guys have stopped using TLS 1.0 and switched TLS 1.2 I was getting the following error Apparently Java 1.8 have TLS 1.2 by default and for Java 1.7 you have to enable it. I have been searching online for few days to enable TLS 1.2. I have tried all the following things but it did not work For each application, enter this command: java ... -Dhttps.protocols=TLSv1.1,TLSv1.2 ... Using JAVA_OPTS, enter the following command in your .profile, shell rc (to affect all Java programs run by the user), or conductor.sh (to just affect Datameer): export JAVA_OPTS="${JAVA_OPTS} -Dhttps.protocols=TLSv1.1,TLSv1.2" This is what I did and boom it worked
2 comments
Read more

Simple IOT Project - Electric Imp Led Light Controller

Recently I went to IBM IOT Hackathon and got Electic IMP device and thought of playing with it and this is the first application I created LED Light controller using Electric IMP device and REST webservice. Overview Skill Level: Beginner Below are detailed steps on how to connect an Electric Imp with environmental sensors to the Watson IoT Platform in order to visualize and monitor your refrigerator in real time. Ingridients   Your WIFI *network name* and *password*  A computer with a web browser  Smartphone with the Electric Imp app I OS  or Android A free Electric Imp developer account    An Electric Imp Explorer kit - purchase from Amazon    Three AA batteries STEP BY STEP  Step 1 - What is demonstrated in this example? Use an Electric Imp to switch on/off light sensor and change the color of light using combination of RGB.  Step 2 - Connect your Electric Imp to the Internet  Set Up Hardware  Plug the Imp001 into the Explorer Kit Board .Power up y
7 comments
Read more