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CodeGym /Courses /Java Core /Bonus task | Lesson 11 | Level 8

Bonus task | Lesson 11 | Level 8

Java Core
Level 8 , Lesson 11
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"I've got awesome news for you. Here are some exercises to reinforce your skills. Do them every day and your skills will grow at an insane speed. They were created especially for IntelliJ IDEA."

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10
Task
Java Core, level 8, lesson 11
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ABCs
The first parameter of the main method is a file name. Count the letters in the file. Display the number of letters. Close the streams.
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10
Task
Java Core, level 8, lesson 11
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Spaces
The first parameter of the main method is a file name. Display the ratio of the number of spaces to the number of all characters. For example, 10.45. 1. Count all the characters (n1). 2. Count the spaces (n2). 3. Display n2/n1*100, rounding to 2 decimal places. 4. Close the streams.
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10
Task
Java Core, level 8, lesson 11
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Two in one
Read 3 file names from the console. Write the contents of the second file to the first file, and then append the contents of the third file to the first file. Close the streams.
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10
Task
Java Core, level 8, lesson 11
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Combining files
Read 2 file names from the console. Write the contents of the second file to the beginning of the first file so that the files are combined. Close the streams.
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20
Task
Java Core, level 8, lesson 11
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Rounding numbers
Read 2 file names from the console. The first file contains real (fractional) numbers, separated by spaces. For example, 3.1415. Round the numbers to integers and write them, separated by spaces, to the second file. Close the streams. The rounding should work like this: 3.49 => 3 3.50 => 4 3.51 => 4
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20
Task
Java Core, level 8, lesson 11
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Symbol frequency
The program is started with one argument: the name of a file that contains text. Calculate how often each symbol is encountered. Sort the results by increasing ASCII code (read about it online). Example: ','=44, 's'=115, 't'=116. Display the sorted results: [symbol1] frequency1 [symbol2] frequency2
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20
Task
Java Core, level 8, lesson 11
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Finding data inside a file
Read a file name from the console. Search the file for information related to the specified id. Display it in the format used in the file. The program is started with one argument: id (an int). Close the streams. The file data is separated by spaces and stored in the following order: id productName
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20
Task
Java Core, level 8, lesson 11
Locked
Threads and bytes
Read file names from the console until the word "exit" is entered. Pass the file name to the ReadThread thread. The ReadThread thread should find the byte that occurs most frequently in the file, and add it to resultMap, where the String parameter is the file name and the Integer parameter is the re
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10
Task
Java Core, level 8, lesson 11
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Files and exceptions
Read file names from the console. If the file does not exist (i.e. an invalid file name is given), then catch the FileNotFoundException, display the invalid file name, and exit the program. Close the streams. Don't use System.exit();
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20
Task
Java Core, level 8, lesson 11
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Building a file
Let's build a file from various pieces. Read file names from the console. Each file has a name: .partN. For example, Lion.avi.part1, Lion.avi.part2, ..., Lion.avi.part37. The file names are supplied in random order. The word "end" is used to stop reading in file names. In the folder where
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"Those previous exercises were for rookies. I've added some more advanced bonus exercises for the old-timers. Just for veterans."

10
Task
Java Core, level 8, lesson 11
Locked
Encryption
Come up with an encryption/decryption mechanism. The program runs with one of the following sets of arguments: -e fileName fileOutputName -d fileName fileOutputName where: fileName is the name of a file to be encrypted/decrypted. fileOutputName is the name of the file where you need to write the re
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20
Task
Java Core, level 8, lesson 11
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Prices
CrUD for a table inside a file. Read a file name for CrUD operations from the console. The program is started with the following arguments: -c productName price quantity Argument values: where id is 8 characters. productName is 30 characters. price is 8 characters. quantity is 4 characters. -c adds
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20
Task
Java Core, level 8, lesson 11
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Prices 2
CrUD for a table inside a file Read a file name for CrUD operations from the console The program runs with one of the following sets of arguments: -u id productName price quantity -d id Argument values: where id is 8 characters productName is 30 characters price is 8 characters quantity is 4 charact
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Comments (41)
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Rene Level 28, Netherlands
24 September 2024
The bonus tasks were sweet but certainly not simple for me. I learned a lot shall we say :) If you want some practice you should definitely try them. I sometimes struggle how to structure my program. What goes into main() and should i create a method for a particular piece of coding. I do get them validated in the end but whether they are good pieces of code....
Simphiwe Level 33, Johannesburg, South Africa
29 March 2023
How do you round down when the float is 2.50?
Mike S Level 28, Saint Louis, United States
14 February 2023
I completed 10 / 13 of these, but tried hard on every one of them. Conceptually, they all made sense. Hope I'm still on the generally right track...
Dawn( #11020889) Level 37, Toronto, Canada
11 December 2022
finally I solve the problems!
Aldo Luna Bueno Level 1, Peru
23 March 2022
Wow, not an easy one. Let's go!
Hoa Nguyen Level 15, Australia Expert
18 February 2022
I think CodeGym should allow checking solutions multiple times to facilitate learning from mistakes.
matemate123 Level 50, Kraków, Poland
26 January 2023
It would be fun, sometimes you're curious about different way to resolve task and you can't check it. So loss. I'm curious, why is that?
Hoa Nguyen Level 15, Australia Expert
18 February 2022
In task 1, what is the meaning of args[0] in new FileReader(args[0]))?
Hoa Nguyen Level 15, Australia Expert
18 February 2022
I got it. In case someone is confused like me, the question asks to pass the file name as the first argument, thus FileReader(args[0]) is to achieve that.
ジョーンズJ Level 47, United States
20 January 2022
私は最後のものに苦労しています...😞、それを確認しようとするたびに私はこれらを間違えます • When the program is started with the arguments "-u id productName price quantity", the product information in the file should be updated. • When the program is started with the arguments "-d id", the line for the product with the specified id should be removed from the file.
John Squirrels Level 40, San Francisco, Poland
2 February 2022
Which task are you referring to?
Jurij Thmsn Level 29, Flensburg, Germany
16 April 2021
Skyrocketing difficulty 🤯 I'd love to have an overview when to use which reader/writer. And which one does exactly what. I know and used FileInputStream, FileOutputStream, FileWriter, FileReader, ByteArrayInputStream, ByteArrayOutputStream, BufferedInputStream, BufferedReader, BufferedWriter, InputStreamReader (...) But I am really confused about the differences, return types and when to use which. before doing the exercises, I recommend to look further into String.format. e.g. here: https://www.youtube.com/watch?v=moQ3Kr8ouiU And how to use TreeSet and substring, too. And make sure not to write and read from the same file at the same time! Keep going!
Sansho Level 19, Bordeaux, France
5 July 2021
Hey Jurij, I don't know if you have the answer nowadays, but this is what I've found and understood: Basically, the streams are working with bytes, while the Writer/Reader with chars. And so, as BufferedStreams are faster than Streams, I guess that BufferedWriter/Reader are faster than Writer/Readers 🙂 So, that means: 1) If you are dealing with binary data (e.g. an image) use Streams. 2) If you are using non-ASCII Unicode characters, e.g. Chinese, use Readers/Writers. 3) If you are using ordinary ASCII text (the traditional 0-127 characters) you can (usually) use either. (thanks to this stackoverflow answer )
Gellert Varga Level 23, Szekesfehervar, Hungary
10 July 2021
Hi Jurij, Streams/Readers: I think once everybody should take the time to study this topic in the Oracle API, for example: https://docs.oracle.com/javase/8/docs/api/java/io/InputStream.html Based on this, I have drawn Stream family trees and Reader family trees for myself, and I made notes about the main classes by translating them into my own native language. I don't claim to understood everything... but you can certainly learn from it, it makes the picture clearer! There you can see exactly what each method returns, what the constructor expects, etc etc.
Chandan Thapa Level 22, Dubai, United Arab Emirates
5 January 2021
It was hard! But learned a lot by doing this! Feels so awesome after completing all!! You can do it!