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02: JavaScript mistakes interview Q&As

Q1. What are the common JavaScript errors or bad practices that you have noticed? A1. 1) Not having proper namespaces and not using AMD (i.e. Asynchronous Model Definition) API to modularize the Java code for improved maintainability. … Read more ›...

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02: Microservices Architecture design patterns & considerations interview Q&As – Part 1

Microservices Architecture Patterns & considerations

This extends 10+ Key Microservices Interview Questions Answered. The architects & developers need to know these microservices design patterns & these are best practices to build robust systems. Q1. Why do we need design patterns for Microservices? A1. The goal of microservices is to increase the velocity of application releases,...

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02: Top 10 Linux interview Q&As

Many production systems run on Linux systems, especially the Cloud infrastructure (i.e. AWS & GCP). Even Android uses the Linux kernel under the hood. So, it really pays to have a good knowledge of Linux.

Q1. How do you check for open ports in Linux?
A1.

…

03: 21+ Java Servlet interview Q&As

Q1. What is a Servlet? Is a Servlet inherently multi-threaded? A1. A Servlet is a Java class that runs within a web container in an application server, servicing multiple client requests concurrently forwarded through the server and the web container. The web browser establishes a socket connection to the host...

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03: 30+ Java architect interview questions & answers – Part 3

Continuation of Java architecture interview Q&As – part 1 & 7+ Java architectural patterns interview Q&As – Part 2. Q3. Can you discuss some of the high level architectures you are experienced with? A3. Be prepared for a white board session on architectures, … Read more ›...

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03: 7 Things you must know about Java locks and synchronized key word

7 Things you must know about Java locks and synchronized key word summarizes the key basics. #1. Each Java class and object (i.e. instance of a class) has an intrinsic lock or monitor. Don’t confuse this with explicit lock utility class that were added in Java 1.5, … Read more...

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03: How would you go about designing an online shopping cart?

This question is a very popular white board session question for both Java architects and experienced JEE Developers. You need to draw on your experience to tackle this question as there are no right or wrong answers. These high level diagrams and summary will help you refresh your memory. Q....

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03: Java 9 to 20 features interview Q&As – text blocks

Q01: What are text blocks? A01: Java 15 introduced text blocks feature to declare multi-line strings. Prior to Java 15

package com.myorg.hello;

public class TextBlocks {

    public static void main(String[] args) {
        String sql =
                " SELECT id, first_nm, last_nm\n"
                        + " FROM employee\n"
                        + " WHERE dept = \"IT\"\n"
                        + " ORDER BY  first_nm, last_nm ASC";
        
        String html =
                " <html>\n"
                        + "   <body>\n"
                        + "     <p>Hello World!</p>\n"
                        + "   </body>\n"
                        + " </html>";

        System.out.println(sql);
        System.out.println("-------------------------------");
        System.out.println(html);
    }
}

package com.myorg.hello;

public class TextBlocks {

public static void main(String[] args) {

String sql =

" SELECT id, first_nm, last_nm\n"

+ " FROM employee\n"

+ " WHERE dept = \"IT\"\n"

+ " ORDER BY first_nm, last_nm ASC";

String html =

" <html>\n"

+ " <body>\n"

+ " <p>Hello World!</p>\n"

+ " </body>\n"

+ " </html>";

System.out.println(sql);

System.out.println("-------------------------------");

System.out.println(html);

}

Outputs:

SELECT id, first_nm, last_nm
 FROM employee
 WHERE dept = "IT"
 ORDER BY  first_nm, last_nm ASC
-------------------------------
 <html>
   <body>
     <p>Hello World!</p>
   </body>
 </html>

SELECT id, first_nm, last_nm

FROM employee

WHERE dept = "IT"

ORDER BY first_nm, last_nm ASC

-------------------------------

<html>

<body>

<p>Hello World!</p>

</body>

</html>

Java 15+ The Pre Java 15 approach is harder to read & … Read more ›...

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03: Kubernetes (aka k8s) interview Q&As – objects & manifest files

Q01. What is a Kubernetes object? A01. One of the key concepts in Kubernetes is the “desired state,” which refers to the configurations of the applications that you want to deploy and run. A desired state includes things like how many instances of applications should be running, … Read more...

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03: Kubernetes (i.e. Minikube) – deploy a spring boot microservice app

This extends Kubernetes (i.e. Minikube) – deploy a node js service.

Docker containers & Kubernetes for deploying Spring Boot microservices. As mentioned earlier in Kubernetes, Docker & Microservices interview Questions & Answers.

Docker gives you application isolation, and solves the dependency hell issues.

…

03: Microservices Architecture design patterns & considerations interview Q&As – Part 2

This extends 02: Microservices Architecture design patterns & considerations interview Q&As – Part 1. 3. Decomposition Design Patterns When decomposing the Microservices, we should avoid having tight coupling between the services. This can be achieved by duplicating the data in the required/dependent services. … Read more ›...

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03: Q16 – Q17 Java Polymorphism vs Overriding vs Overloading

Polymorphism is the ability of a class instance to behave as if it were an instance of another class in its inheritance tree, most often one of its ancestor classes. Overriding is the means by which you achieve polymorphism. Java Polymorphism vs Overriding vs Overloading explained in detail to handle drill down Java OOP interview questions with ease when quizzed further.

…

03: Shell script interview Q&As for Java developers

Q1 How will you go about reading a CSV file as shown below?

Portfolio,Account,PositionIndicator,Amount
AA123,CURR-AUD,CREDIT,2244.14000000
AA123,CURR-AUD,CREDIT,5.60000000
AA123,CURR-AUD,DEBIT,2249.74000000
AA123,CURR-GBP,CREDIT,0.01000000
AA123,CURR-GBP,DEBIT,0.01000000

Portfolio,Account,PositionIndicator,Amount

AA123,CURR-AUD,CREDIT,2244.14000000

AA123,CURR-AUD,CREDIT,5.60000000

AA123,CURR-AUD,DEBIT,2249.74000000

AA123,CURR-GBP,CREDIT,0.01000000

AA123,CURR-GBP,DEBIT,0.01000000

#!/bin/bash
 
# $# means number of arguments supplied to the command. In this case the file to to be read
if [ $# != 1 ]; then
    echo "Usage: $0 input-file"
    exit 1
else
    infile=$1
fi
 
# assign file descriptor 3 to input file
exec 3< $infile
 
# read till the end of the file
until [ $done ]
do
    read <&3 myline
 #$? is the exit code, and 0 means success and != 0 means not success. That is no line is read.
    if [ $? != 0 ]; then
        done=1
        continue
    fi
 
    # process file data line-by-line in here
 
    echo $myline
done

#!/bin/bash

# $# means number of arguments supplied to the command. In this case the file to to be read

if [ $# != 1 ]; then

echo "Usage: $0 input-file"

exit 1

else

infile=$1

# assign file descriptor 3 to input file

exec 3< $infile

# read till the end of the file

until [ $done ]

read <&3 myline

#$? is the exit code, and 0 means success and != 0 means not success. That is no line is read.

if [ $? != 0 ]; then

done=1

continue

# process file data line-by-line in here

echo $myline

done

Q2 How will you read and then write to another file?

Portfolio,Account,PositionIndicator,Amount
AA123,CURR-AUD,CREDIT,2244.14000000
AA123,CURR-AUD,CREDIT,5.60000000
AA123,CURR-AUD,DEBIT,2249.74000000
AA123,CURR-GBP,CREDIT,0.01000000
AA123,CURR-GBP,DEBIT,0.01000000

Portfolio,Account,PositionIndicator,Amount

AA123,CURR-AUD,CREDIT,2244.14000000

AA123,CURR-AUD,CREDIT,5.60000000

AA123,CURR-AUD,DEBIT,2249.74000000

AA123,CURR-GBP,CREDIT,0.01000000

AA123,CURR-GBP,DEBIT,0.01000000

#!/bin/bash
 
# $# means number of arguments supplied to the command
if [ $# != 2 ]; then
    # $0 is the script name  $1 is input file and $2 is output file  
    echo "Usage: $0 input-file output-file"
    exit 1
else
    infile=$1
fi
 
# assign file descriptor 3 to input file
exec 3< $infile
 
# read till the end of the file
until [ $done ]
do
    read <&3 myline
 #$? is the exit code, and 0 means success and != 0 means not success. That is no line is read.
    if [ $? != 0 ]; then
        done=1
        continue
    fi
    
   # process file data line-by-line
    
    # append to output file. If you run it more than once, it keeps appending.
    echo $myline >> $2 
done

#!/bin/bash

# $# means number of arguments supplied to the command

if [ $# != 2 ]; then

# $0 is the script name $1 is input file and $2 is output file

echo "Usage: $0 input-file output-file"

exit 1

else

infile=$1

# assign file descriptor 3 to input file

exec 3< $infile

# read till the end of the file

until [ $done ]

read <&3 myline

#$? is the exit code, and 0 means success and != 0 means not success. That is no line is read.

if [ $? != 0 ]; then

done=1

continue

# process file data line-by-line

# append to output file. If you run it more than once, it keeps appending.

echo $myline >> $2

done

Q3 How will you read the file and then write to another file with CSV data in different order? …...

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Categories

Blog Archives

02: JavaScript mistakes interview Q&As

02: Microservices Architecture design patterns & considerations interview Q&As – Part 1

02: Top 10 Linux interview Q&As

03: 21+ Java Servlet interview Q&As

03: 30+ Java architect interview questions & answers – Part 3

03: 7 Things you must know about Java locks and synchronized key word

03: How would you go about designing an online shopping cart?

03: Java 9 to 20 features interview Q&As – text blocks

03: Kubernetes (aka k8s) interview Q&As – objects & manifest files

03: Kubernetes (i.e. Minikube) – deploy a spring boot microservice app

03: Microservices Architecture design patterns & considerations interview Q&As – Part 2

03: Q16 – Q17 Java Polymorphism vs Overriding vs Overloading

03: Shell script interview Q&As for Java developers

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