Java on Samarthya

Naming Convention Policy for Kafka topics

Wed, 13 Jul 2022 12:00:00 +0000

Creating a Topic in a kafka-cluster is easy and well documented for the kafka-topics.sh or even the official API documentation.

 bin/kafka-topics.sh --help

The complexity arises, when you are trying to enforce a standard way of defining topic naming. There are many ways to identify the right convention based on your need, but to enforce such a topic convention while you are creating one is explained in this 5 steps blog.

JUNIT5: Learning how to write the code the right way!

Sat, 05 Jun 2021 11:31:24 +0000

JUnit was developed by Kent Beck and Erich Gamma. Its first version was released in 1997.

JUnit 5 = JUnit Platform + JUnit Jupiter + JUnit Vintage — https://junit.org/junit5/docs/current/user-guide/

It is powerful testing framework, with many modules. These modules are part of three sub-projects

Java Stream: Examples

Mon, 26 Apr 2021 09:07:19 +0000

Streams are convenient way to reduce the line of codes, but an understanding them is equally challenging. I write this blog, after realising a desperate attempt at solving a trivial problem just took overwhelming time. (Could be that I am getting old, but never late to learn things again)

Smallest Integer

Sat, 24 Apr 2021 05:43:46 +0000

Code available here.

The ask was to identify the smallest possible integer (> 0) in the array of integers.

Example
#

[-1,2] -> 1
[-1,-2] -> 1
[1,3] -> 2

I was initially thinking of using sets and then finding out the missing one, but then reaized it is simpler and I do not need sets

Fortune v1.0

Wed, 16 Dec 2020 10:50:24 +0000

In one of recent discussions with Mr. X I was asked about my approach to solving the Linux cookie problem

A random quote
Repository will be a text file
Each quote will be segregated by a '%'
Can be multiline.

I always believe in incremental steps so here is what I could think of

Nth Prime

Tue, 15 Dec 2020 08:21:32 +0000

Prime number is an age old problem. I am trying to solve it via streams.

class PrimeCalculator {

 public int nth(int nth) {
 if (nth <= 0)
 throw new IllegalArgumentException();

 // Will skip the nth - 1
 // 2 to n-1
 return IntStream.iterate(2, i -> i + 1).filter(PrimeCalculator::isPrime).skip(nth - 1).findFirst().getAsInt();
 }

 public static boolean isPrime(int x) {
 // till half of x
 return IntStream.rangeClosed(2, (int) (x/2) ).dropWhile(i -> x % i != 0).findFirst().isEmpty();
 }
}

Explanation
#

public int nth(int nth) {
 if (nth <= 0)
 throw new IllegalArgumentException();

 // Will skip the nth - 1
 // 2 to n-1
 return IntStream.iterate(2, i -> i + 1).filter(PrimeCalculator::isPrime).skip(nth - 1).findFirst().getAsInt();
 }

The method nth(int) allows you to return the nth prime starting at 2, 3, 5....

JavaStream: Characters

Fri, 13 Nov 2020 10:20:02 +0000

Continuing from the last blog how about checking a pangram using streams.

public class PangramChecker {

 private String allChars = "abcdefghijklmnopqrstuvwxyz";

 public boolean isPangram(String input) {
 if (input.length() <= 0 || input.isBlank()){
 return false;
 }
 return (allChars.chars().map(x -> (char) x).filter(x -> input.toLowerCase().indexOf(x) >= 0).count() == 26);
 }

}

All the for loops have been squeezed into a simple line

Java Streams

Thu, 12 Nov 2020 11:47:49 +0000

Stream is an new abstraction that lets one process data in a declarative way.

A stream does not store data and, in that sense, is not a data structure. It also never modifies the underlying data source.

The easiest way to learn a new API or a construct is by trying it. So here is an exercise that I tried to learn the Stream API. This is an exercise from exercism.io.