Technical Java Interview Prep for IT professionals

Welcome message from Benji

Check out the resource and review as needed. Take it and own the knowledge. You can always refer to your resources.

Please take a moment to take this survey: https://docs.google.com/forms/d/e/1FAIpQLSfk7bEgb11c3men0VRSpV4Euwx70dNqbL4DsL4qLDE1BKQfrw/viewform?usp=sf_link

Also here is the link to join discord group:

https://discord.gg/B3kawGkqFQ

or try this https://discord.gg/2FZE72sT3P

Given two strings, return common letters

logic,

find short and long strings

shorter string characters can then be compared with longer string characters

if there is a match, add it inside a new string

repeat the steps, finally print new string.

  /*

      Greatest ascending difference

      Given integer array,  find the greatest difference between two elements:

      x & y, where y>x and y comes after x

      return -1 if there is no difference.

      [4,2,5,8,1] returns 6 because ascending difference is 2 - 8

      [6,5,4,3,2,1] returns -1 because there is no ascending difference

  */

in this solution, we are solving if given array is sorted. Return true otherwise false.

Note that if we change the index, we can see if the part of the array is sorted or not.

We will use stdin box in the onecompiler website to mimic what interviewers use to provide input for analysis. Such idea is key to getting started with coding task, and most importantly learn ways to filter input data such as using java 8 lambda operation. Lambda should not scare you because in this lesson, it will help you write much less code when there is already a lot of lines of code to partly minify the lines.

We will look into how to utilize Scanner and BufferReader classes to read from standard input known as stdin. This logic is an oldest and yet it is still in use in today's world.

I highly recommend to code hands on while you watch the video lesson. You will also have access to the code written in the lesson. See Resources tab that will include the external link to original code at onecompiler website.

Thank you for your hard work. Now you are one step closer being prepared in the interview.

Read values of Stdin using Buffered Reader class.

Note that we take the lesson 1 function and make changes in a new file.

convert the method into return type.

using ArrayList container.

pay attention to method signature, void is removed and Arralist<String> is added. Thus, we must return the list at the end of the method.

Now the method is stores stdin values in a list.

compare what we did with lesson 3 and see if you notice any differences.

made many mistakes and most of them were to pinpoint what parts you should remember the most. Some other mistakes were mainly because I was occupied with two or more tasks at the time of recording lead to some simple mistakes. At the end of the video, though, I was able to fix all mistakes for your reference.

Have you not joined the discord server? We are waiting for you to arrive! What are you waiting for? Download the discord app on your smart device or use web to join discord channel. See you there.

https://discord.gg/2FZE72sT3P

Analysis of how we can extract numbers from given list of items through stdin box. We will try lambda and regular expression solutions to see which one works for us. Check it out.

Please take a moment to take this survey: https://docs.google.com/forms/d/e/1FAIpQLSfk7bEgb11c3men0VRSpV4Euwx70dNqbL4DsL4qLDE1BKQfrw/viewform?usp=sf_link

Also here is the link to join discord group: https://discord.gg/2FZE72sT3P

In this video, you will work alongside to create a simple Machine class to prepare a plain java code. Legacy based, but still, you will learn how to write the functions and more importantly see how constructors were used in this example first hand. You may think this lesson as the first step into object oriented programming, a good refresher for some friends. Please use onecompiler or any similar online compiler to write code on these lessons.

https://onecompiler.com/

See the completed code below in Resources tab.

This is the part where we will add the functions/methods. Apply in your own program and compare results. Good luck.

For example, why don't you create another class other than Machine. Name your own program such as Cars, Animals or Shapes. and so on. Good luck.

See the completed code below in Resources tab.

See the shared link to view the completed code.

Character class contains methods such as isLetter or digit. We will begin utilizing isLetter in this lesson. Please apply and make your own code during or after watching the lessons. Repetition in writing code and improving your existing code are the keys to mastering a decent programming foundation. Good luck.

In the second part of the video, we continue looking at the data and separate the characters given the index.  At the end of the video or while you watch it, please apply the code and practice.

Check for understanding.

Trial and error is what keeps me going. It's the natural existence of learning hands on. On this lesson, I would like you to try out coding as you watch the video or begin trial after the lesson. It is also imperative to make your own variation of the code to cover more use cases. On this one, we looked at two main use cases: finding the middle value of odd and even numbers. Good luck with your practice. See you on the next lesson.

Check out the resources. Hope that helps.

Finding the count of each element in given lists.

While we get the sum of all numbers, there was a Math solution that only works for consecutive numbers. So that was the epic failure realized, you will see success nearing the end, duh, that was something :)

Find missing number has one requirement that should be mentioned. Numbers are either consecutive and it can also be between a low and a high numbers. For example 1-10, used in our lesson.

Check out the completed code for your reference. Hope that helps.

How to use ampersand to check for odd and even numbers.

As in binary case, take 0 as even and 1 as odd to utilize ampersand in the comparison.

Next, figure out how to convert numbers into binary format.

Apply how to use Math.max(var1, var2); // that returns higher value

Check out the Binary Gap Link in the external resources part.

create your own random object data that consists of letters, numbers, characters and be sure to include a few vowels for testing purposes.

create your countVowel( ) method and isVowel( )

create your toOnePiece( ) method, learn it then own it.

Once you are able to add all data values as a string type,

now you may utilize the charAt() function to check for isVowel( )

for example: add a for loop then inside the loop:

if( isVowel(onepiece.charAt(i))){   }

now you can increment the count by 1.

Finally print the count value.

Practice this code a few times and you will be mastering it. Make it better and make it your own.

you are given a text that has duplicated values; aabbccdd

create a new string object and set it to your new function: removeDuplicates()

create the function/method now:

removeDuplicates(String text){     }

inside the function above, do the following,

initialize a new string empty.

create a for loop and follow the video lesson to complete the logic.

Learn more about negating in if-then-else block. I highly recomment your own trial and error rather than searching for more resources. You will see one example in this lesson. See if you can make your own logic from it. Take it and own it. Good luck.

Step 1 and 2: Solve by one liner code.

Step 3 and 4: Solve by a while loop

Step 4: Solve by a for loop

Step 5: Reverse given text word by word.

You can see the final code here: https://onecompiler.com/java/3xn69dqas

Downloadable resource is the same as the link above. If it does not work, copy and paste the web address in a browser:

https://onecompiler.com/java/3xn69dqas

That should do the trick. Thank you for your hard work.

You may find the code link here: https://onecompiler.com/java/3xn69dqas

You may also find it in the External Resources.

See original codes for your reference.

Thanks for listening and watching.

Once you are done here,

Check out the next lesson about ArrayList reversal of random objects.

ArrayList reversal for multiple types via single method created for all object types. Although the method is compatible, note that it is not type safe for applications. You may only use this as a logic in your interview or if asked in your future company to perform such a trivial function for some reason /:

Thanks for doing your best. Check out bonus lessons as they may be added time to time.

Understand how to use a boolean flag to check for true or false of some conditions.

Given text that is passed as an argument compared to the other text set inside the code. Figure out how to compile java code and run after that. This code can run in other platforms that has java installed.