Super lost help

Question about the task

Under discussion

I understand that between ADDED and REMOVED you have to have a SAME line between them. What I don't understand is how exactly the content of the files are layered. One attempt I tried timed out and I thought it would work but time is a factor of course.

Read 2 file names from the console: file1 and file2.
Both files contain text, but file2 is an updated version of file1. Some of the lines are still the same.
You need to create a merged version of the lines by writing them to the lines list.
The ADDED and REMOVED labels can't be used consecutively—they must always separated by the SAME label.
The example includes empty lines for clarity.
Neither the original file nor the updated file have empty lines!

Example 1:
original updated merged file1: file2: Result: (lines) line1 line1 SAME line1 line2 REMOVED line2 line3 line3 SAME line3 line4 REMOVED line4 line5 line5 SAME line5 line0 ADDED line0 line1 line1 SAME line1 line2 REMOVED line2 line3 line3 SAME line3 line4 ADDED line4 line5 line5 SAME line5 line0 REMOVED line0

Example 2:
original updated merged file1: file2: Result: (lines) line1 line1 SAME line1 line0 ADDED line0

In the example, empty lines mean that the line is not in the specified file.

Requirements:

The Solution class must contain a LineItem class.
The Solution class must have an enum called Type.
The Solution class must have a public static List<LineItem> field called lines that is initialized immediately.
In the main(String[] args) method, the program must read file names from the console (use BufferedReader).
In the main(String[] args) method, the BufferedReader used for reading input from the console must be closed after use.
The program must read the contents of the first and second file (use FileReader).
The file input streams (FileReader) must be closed.
The lines list should contain the merged version of the lines from the files. Each line should start with the label ADDED, REMOVED, or SAME, depending on the action taken.

package com.codegym.task.task19.task1916; import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.List; /* Tracking changes */ public class Solution { public static List<LineItem> lines = new ArrayList<>(); public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String filenameA = br.readLine(); String filenameB = br.readLine(); br.close(); br = new BufferedReader(new FileReader(filenameA)); BufferedReader brFileB = new BufferedReader(new FileReader(filenameB)); while (br.ready() && brFileB.ready()) { String lineA = br.readLine(); String lineB = brFileB.readLine(); if (lineA == null && lineB == null) break; if (lineA.equals(lineB)) { lines.add(new LineItem(Type.SAME, lineA)); } else if (lineA.isEmpty() && !lineB.isEmpty()) { lines.add(new LineItem(Type.ADDED, lineB)); } else if (!lineA.isEmpty() && lineB.isEmpty()) { lines.add(new LineItem(Type.REMOVED, lineA)); } } br.close(); brFileB.close(); } public static enum Type { ADDED, // New line added REMOVED, // Line deleted SAME // No change } public static class LineItem { public Type type; public String line; public LineItem(Type type, String line) { this.type = type; this.line = line; } } }

Comments (8)

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Denis

Level 25 , Vancouver, Canada

19 May 2019, 07:41

Your first option was very close ! ArrayList it is not necessary ! I read two lines at the same time and passed.

BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String fileName1 = reader.readLine();
        String fileName2 = reader.readLine();
        reader.close();

        BufferedReader lineReader1 = new BufferedReader( new FileReader(fileName1));
        BufferedReader lineReader2 = new BufferedReader( new FileReader(fileName2));
        String line1 = lineReader1.readLine();
        String line2 = lineReader2.readLine();
        String line1Next = lineReader1.readLine();
        String line2Next = lineReader2.readLine();
        while(true) {

            if (line1Next == null && line2Next == null) {
                if ( line1 != null ) lines.add( new LineItem(Type.REMOVED, line1) );
                if ( line2 != null ) lines.add( new LineItem(Type.ADDED, line2) );
                break;
            }
            if ( line1.equals(line2) ) {
                lines.add( new LineItem(Type.SAME, line1) );
                line1 = line1Next;
                line2 = line2Next;
                line1Next = lineReader1.readLine();
                line2Next = lineReader2.readLine();
            } else if ( line1.equals(line2Next) ) {
                lines.add( new LineItem(Type.ADDED, line2) );
                line2 = line2Next;
                line2Next = lineReader2.readLine();
            } else if ( line1Next.equals(line2) ) {
                lines.add( new LineItem(Type.REMOVED, line1) );
                line1 = line1Next;
                line1Next = lineReader1.readLine();
            }
        }
        lineReader1.close();
        lineReader2.close();

+13

lordheraldor

Level 23 , Newark, United States

20 May 2019, 00:55

Honestly, I didn't think about it like that. I wish I'd thought about getting two lines at a time if I was that close haha.

Daniel Walbolt

Level 22 , Waterville, United States

2 August 2020, 22:16

Funny enough, this code does not work when the final two lines are the same. It will be ADDED AND REMOVED the same line. I tried making a program for like 2 hours straight to be able to discern every possible situation, but didn't think about making something just for what they were testing.

Павел Артеменко

Level 41 , Krasnodar, Russian Federation

27 April 2019, 09:23

useful

Simple diff algorithm

lordheraldor

Level 23 , Newark, United States

30 April 2019, 14:19

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String filenameA = br.readLine();
        String filenameB = br.readLine();

        br.close();

        br = new BufferedReader(new FileReader(filenameA));
        BufferedReader brFileB = new BufferedReader(new FileReader(filenameB));

        String lineA = br.readLine();
        String lineB = brFileB.readLine();
        //No empty lines
        while (br.ready() && brFileB.ready()) {
            if (lineA == null && lineB == null) break;

            if (lineA.equals(lineB)) {
                lines.add(new LineItem(Type.SAME, lineA));
                lineA = br.readLine();
                lineB = brFileB.readLine();
            } else {
                lineA = br.readLine();
                if (lineA.equals(lineB)) {
                    lines.add(new LineItem(Type.REMOVED, lineA));
                    lineB = brFileB.readLine();
                } else {
                    lines.add(new LineItem(Type.ADDED, lineB));
                    lineB = brFileB.readLine();
                }
            }
        }

        br.close();
        brFileB.close();/code>

The same problem unfortunately

Павел Артеменко

Level 41 , Krasnodar, Russian Federation

30 April 2019, 17:07

You need first to load both files in ListArrays, cause if lines are not equals you need to check where is nearest match in lines that follows: - if it is between current line in new file and some further line in old file - thats removal; - if it is between current line in old file and some further line in new file - thats addition;

lordheraldor

Level 23 , Newark, United States

4 May 2019, 18:20

String lineA = br.readLine();
        String lineB = brFileB.readLine();

        LinkedList<String> lineAList = new LinkedList<>();
        LinkedList<String> lineBList = new LinkedList<>();

        lineAList.add(lineA);
        lineBList.add(lineB);

        while (br.ready()) {
            lineA = br.readLine();
            lineAList.add(lineA);
        }

        br.close();

        while (brFileB.ready()) {
            lineB = brFileB.readLine();
            lineBList.add(lineB);
        }

        brFileB.close();

        for (int i = 0; i < lineAList.size(); i++) {
            if (lineAList.get(i).equals(lineBList.get(i))) {
                lines.add(new LineItem(Type.SAME, lineAList.get(i)));
            } else {
                for (int j = i; j < lineBList.size(); i++) {
                    if (lineAList.get(i).equals(lineBList.get(j))) {
                        lines.add(new LineItem(Type.ADDED, lineBList.get(j)));
                        break;
                    } else if (lineAList.get(j).equals(lineBList.get(i))) {
                        lines.add(new LineItem(Type.REMOVED, lineAList.get(i)));
                        break;
                    }
                }
            }
        }

Still no.

Павел Артеменко

Level 41 , Krasnodar, Russian Federation

4 May 2019, 19:31

PMed more evident advice.