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Transactionality

Java Core, Level 7, Lesson 10

Under discussion

I cannot see the problem here, it should work just fine

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 java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.Iterator; import java.util.List; /* Transakcyjność */ public class Solution { public static List<String> allLines = new ArrayList<>(); public static List<String> linesForRemoval = new ArrayList<>(); public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String file1 = reader.readLine(); String file2 = reader.readLine(); reader.close(); FileReader fr1 = new FileReader(file1); FileReader fr2 = new FileReader(file2); BufferedReader bfr1 = new BufferedReader(fr1); BufferedReader bfr2 = new BufferedReader(fr2); while (bfr1.ready()){ allLines.add(bfr1.readLine()); } while (bfr2.ready()){ linesForRemoval.add(bfr2.readLine()); } Solution s = new Solution(); s.joinData(); fr1.close(); fr2.close(); bfr1.close(); bfr2.close(); } boolean hasit = false; public void joinData() throws CorruptedDataException { if (allLines.containsAll(linesForRemoval)) allLines.removeAll(linesForRemoval); else allLines.clear(); throw new CorruptedDataException(); } }

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Jonas

Level 41 , Vilnius, Lithuania

8 June 2020, 10:39

You throw the exception if allLines contains allLines from removalLines, as Annemiek said, you should wrap your if else statements with curly brackets, so that in first brackets there is allLines.removeAll(linesForRemoval); and in else there are allLines.clear();throw new CorruptedDataException();

if (allLines.containsAll(linesForRemoval)){
        allLines.removeAll(linesForRemoval);
   } else{
        allLines.clear();
       throw new CorruptedDataException();
}
    }

AnnemiekFF

Level 41 , Breda, Netherlands

24 April 2020, 13:41

Please use { } in your if, else statements. For now you have written:

if( contains the line) = remove those lines.
otherwise remove everything.
After that throw a new exception no matter which step of the if else you took.