The code is quite obvious and works ok.

Question about the task

Transactionality

Java Core, Level 7, Lesson 10

Resolved

The code is quite obvious and works ok. Why it does not pass?

Make the joinData method transactional, i.e. if it fails, then the data must not be changed.
1. Read 2 file names from the console.
2. Read from the files line by line. Read from the first file into allLines, from the second file — into linesForRemoval.
In the joinData method:
3. If the allLines list contains all the lines from linesForRemoval, then remove from the allLines list all the lines that are in linesForRemoval.
4. If the condition in Item 3 is not satisfied, then:
4.1. clear the data in allLines
4.2. throw a CorruptedDataException
The joinData method should be called in main. Handle all exceptions in the main method.
Don't forget to close the streams.

Requirements:

The Solution class must contain a public static List<String> field called allLines.
The Solution class must contain a public static List<String> field called linesForRemoval.
The Solution class must have a public void joinData() method that can throw a CorruptedDataException.
The program should read the names of two files from the console.
The program must read line by line from the first file into the allLines list.
The program must read line by line from the second file into the linesForRemoval list.
The joinData method must remove from the allLines list all lines in the linesForRemoval list if allLines contains all the lines in the linesForRemoval list.
The joinData method must clear the allLines list and throw a CorruptedDataException, if allLines does not contain all the lines in the linesForRemoval list.
The joinData method should be called in main.

package com.codegym.task.task17.task1721; import javax.imageio.IIOException; import java.io.File; import java.io.IOException; import java.nio.file.Path; import java.nio.file.Paths; import java.util.ArrayList; import java.util.List; import java.util.Scanner; /* Transactionality */ public class Solution { public static List<String> allLines = new ArrayList<>(); public static List<String> linesForRemoval = new ArrayList<>(); private static String fileName1; private static String fileName2; public static void main(String[] args) { Scanner sc = new Scanner(System.in); fileName1 = sc.nextLine(); fileName2 = sc.nextLine(); sc.close(); Solution solution = new Solution(); try { solution.joinData(); } catch (IOException e) { if (e instanceof CorruptedDataException) System.out.println("Not all lines present"); else e.printStackTrace(); } //System.out.println(allLines); } public void joinData() throws IOException { Scanner readFile = new Scanner(Paths.get(fileName1)); while (readFile.hasNextLine()) { allLines.add(readFile.nextLine()); } //System.out.println(allLines); readFile.close(); Scanner readFileForRemove = new Scanner(new File(fileName2)); while (readFileForRemove.hasNextLine()) linesForRemoval.add(readFileForRemove.nextLine()); readFileForRemove.close(); //System.out.println(linesForRemoval); if (allLines.containsAll(linesForRemoval)) allLines.removeAll(linesForRemoval); else { allLines.clear(); throw new CorruptedDataException(); } } }

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Nouser

Level 36 , Germany

9 January 2021, 13:54

solution

The requirements are not really easy to understand for non nativ English speakers. If you read point 2 again, then you'll see at its end: In the joinData method: 3. (point 3 requirement) So I'd say point 1 + 2 are not to code in the joinData method, while point 3 needs to be there

Dmitri

Level 22 , Seversk, Russia

9 January 2021, 14:12

Thank you))