Java Pivot Table

Java Pivot Table. Java – Pivot Table using Streams 1 Introduction Today let us see how we can implement a pivot table using java 8 streams Raw data by itself does not 2 CSV Data Represented as a POJO We use the following POJO representing baseball players and their salaries The data 3 Define the Pivot.

PivotingJoins with Custom TuplesUsing Parallel PivotingTake It For A Spin!I will construct a Map of Actor objects and for each Actor a corresponding List of film ratings of films that a particular Actor has appeared in Here is an example of how a pivot entry for a specific Actormight look like expressed verbally “John Doe participated in 9 films that were rated &#39PG13&#39 and 4 films that were rated &#39R&#39” We are going to compute pivot values for all actors in the database The Sakila database has three tables of interest for this particular application 1 “film” containing all the films and how the films are rated (eg “PG13” “R” etc) 2 “actors” containing (made up) actors (eg “MICHAEL BOLGER” “LAURA BRODY” etc) 3 “film_actor” which links films and actors together in a manytomany relationship The first part of the solution involves joining these three tables together Joins are created using Speedment&#39s JoinComponent which can be obtained like this Once we have the JoinComponent we can start defining Join relations that we need to co As we noticed in the example above we have no actual use of the FilmActor object in the Stream since it is only used to link Film and Actor entities together during the Join phase Also the generic Tuple3 had general get0() get1() and get2()methods that did not say anything about what they contained All this can be fixed by defining our own custom “tuple” called ActorRatinglike this When Join objects are built using the build()method we can provide a custom constructor that we want to apply to the incoming entities from the database This is a feature that we are going use as depicted below In this example we proved a class with a constructor (the method reference ActorRatingnew gets resolved to new ActorRating(fa actor film)) that just discards the linking FilmActor object altogether The class also provided better names for its properties which made the code more readable The solution with the custom ActorRatingclass will produce exactly the same output result as the One cool thing with Speedment is that it supports the Stream method parallel()outofthebox So if you have a server with many CPUs you can take advantage of all those CPU cores when running database queries and joins This is how parallel pivoting would look like We only have to add a single line of code to get parallel aggregation The default parallel split strategy kicks in when we reach 1024 elements Thus parallel pivoting will only take place on tables or joins larger than this It should be noted that the Sakila database only contains 1000 films so we would have to run the code on a bigger database to actually be able to benefit from parallelism In this article we have shown how you can compute pivot data from a database in Java without writing a single line of SQL code Visit Speedment opensource on GitHubto learn more Read more about other features in the the User&#39s Guide.

Making Pivot Tables With Java Streams From Databases DZone Java

How to create pivot table in Java EasyXLS Excel library can be used to export Excel files in Java The library works with any Java SE application and without MS Excel installed Find more about Getting Started with EasyXLS Step 1 Download and install EasyXLS Excel Library for Java.

PivotTable.js

PivotTablejs is an opensource Javascript Pivot Table (aka Pivot Grid Pivot Chart CrossTab) implementation with drag&#39n&#39drop functionality written by Nicolas Kruchten To see what it can do and how browse the examples below or check out the documentation wiki for full details.