讀入兩個文件並按元素比較每一行

Question

我想讀入兩個文件並比較兩個文件的每個元素。 文件的所有行都是這樣的： 17-995-364，Ruh，Konrad，Julia我有兩個類：

public class Student {
    public String name;
    public Student (String name) {
        this.name = name;
    }
    public static String[] toString(String name)
    {
        String s1 = ""; String s2 = ""; String s3 = ""; String s4 = "";
        int position = 0;
        for(int i = 0; name.charAt(i) != name.length(); i++)
        {
            if (name.charAt(i) == ',') {++position; continue;}
            if (position == 0) s1 += name.charAt(i);
            if (position == 1) s2 += name.charAt(i);
            if (position == 2) s3 += name.charAt(i);
            if (position == 3) s4 += name.charAt(i);
        }
        String[] s = new String[4];
        return s;
    }
}

和

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;

/**
 * This class reads-in a *.csv file.
 * -
 */
public class CSVReader {

    /**
     * This method reads-in a *.csv file and
     * saves each element as entry
     * of a bidimensional array.
     *
     * @param filename track to the file, z.b. ".Root/test/echo.csv"
     * @return {@code String[][] s}  where {@code s[i][j]} is the j-th value 
     * in the i-th line
     */
    public static String[][] readCSV(String filename) {
        ArrayList<String[]> result = new ArrayList<>();

        BufferedReader br = null;
        String line = "";
        String cvsSplitBy = ",";
        StringBuilder  stringBuilder = new StringBuilder();
        for (int i = 0; br != null; ++i)
        {
            for (int j = 0; j < 4;)
            {
                if (result.charAt(i) == ',') {++j; continue;}
                result[i][j] += name.charAt(i);
            }
        }
        try {
            br = new BufferedReader(new FileReader(filename));
            while ((line = br.readLine()) != null) {
                result.add(line.split(cvsSplitBy));
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return result.toArray(new String[result.size()][]);
    }
}

CSVReader的類尚未完成，主類也未完成：

/ ** * Java程序的主類。 * * /

公共班級主要{

public static void main(String[] args) {

    /**
     * Read in "./Root/files/echo.csv" und "./Root/files/file1.csv"
     * and output the respective warning on System.out
     */
    String[][] codeexpert = CSVReader.readCSV("./Root/files/file1.csv");
    String[][] echo = CSVReader.readCSV("./Root/files/echo.csv");
    for (int i = 0, i != file1.end ; ++i)
    {
        System.out.println(readCSV(file1(i));
    }
    System.out.println(codeexpert);
    System.out.print(echo);
}

}

我想做一個排序功能，但在此之前，主類中的輸出必須正確。 目前，我有編譯錯誤。 如果我得到想要的元素，排序功能對我來說不是問題。 另外，我應該使用Student類的toString函數。 我該如何解決主類中的編譯錯誤，並且readSCV這樣的方法正確嗎？ 編譯錯誤為：

編譯錯誤為：

./Root/src/Main.java:16: error: ';' expected
        for (int i = 0, i != file1.end ; ++i)

./Root/src/Main.java:16: error: illegal start of expression
        for (int i = 0, i != file1.end ; ++i)

./Root/src/Main.java:16: error: ';' expected
        for (int i = 0, i != file1.end ; ++i)

./Root/src/Main.java:16: error: illegal start of expression
        for (int i = 0, i != file1.end ; ++i)

./Root/src/Main.java:16: error: ')' expected
        for (int i = 0, i != file1.end ; ++i)

./Root/src/Main.java:16: error: ';' expected
        for (int i = 0, i != file1.end ; ++i)

./Root/src/Main.java:18: error: ')' expected
            System.out.println(readCSV(file1(i));

7個錯誤

我需要這樣：

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.util.Arrays;
import java.util.List;

import static org.junit.Assert.assertEquals;

/**
 * Helper functions for testing
 */
public class MatchingTest {

    /**
     *  Current Project Directory.
     */
    public final static String curDir = Paths.get("").toAbsolutePath().toString() + "/Root/";


     static ByteArrayOutputStream outContent = new ByteArrayOutputStream();
    static ByteArrayOutputStream errContent = new ByteArrayOutputStream();

    /**
     * Copies the test files to the files directory, overwriting existing files
     *
     * @param  dir Directory in which test files are stored
     * @param test_prefix E.g. "00", "01", etc
     */
    public static void copy_testfiles(String dir, String test_prefix) {

        try {


            // Paths to test files
            Path test_echo = Paths.get(curDir + dir + test_prefix + "_echo.csv");
            Path test_codeexpert = Paths.get(curDir + dir + test_prefix + "_codeexpert.csv");

            // Target path
            Path target_echo = Paths.get(curDir + "files/echo.csv");
            Path target_codeexpert = Paths.get(curDir + "files/codeexpert.csv");

            Files.copy(test_echo, target_echo, StandardCopyOption.REPLACE_EXISTING);
            Files.copy(test_codeexpert, target_codeexpert, StandardCopyOption.REPLACE_EXISTING);

        } catch (IOException e) {
            throw new RuntimeException("Could not copy test files", e);
        }
    }

    /**
     * Reads the file containing the expected output and returns it as a String
     * @param dir Directory in which test files are stored
     * @param test_number
     * @return Contents of  ./dir/[test_number]_output.txt
     */
    static String output(String dir, String test_number) {
        try {
            Path test_output = Paths.get(curDir + dir + test_number + "_output.txt");
            return new String(Files.readAllBytes(test_output));
        } catch (IOException e) {
            throw new RuntimeException("Could not open test solution file", e);
        }
    }

    /**
     * This method compares the output to the correct solution.
     * It should be able to differentiate between lines that don't match the formating,
     * lines that are misordered and lines that shouldn't be in the oputput at all
     *
     * @param expected Answer that we expect
     * @param actual   Submitted answer
     */
    static void compare(String expected, String actual) {
        // Split strings into lines and save in a collection
        List<String> expected_lines = Arrays.asList(expected.split("(\r\n|\r|\n)", -1));
        List<String> actual_lines = Arrays.asList(actual.split("(\r\n|\r|\n)", -1));


        String name = "[a-zA-Z'-]+( [a-zA-Z'-]+)?";
        String pattern1 = name + " is enrolled to " + name + " in Echo, but registered with "  + name +  " in CodeExpert.";
        String pattern2 = name + " is enrolled to " + name + " in CodeExpert, but registered with "  + name + " in Echo.";
        String pattern3 = name + " is in CodeExpert but not in Echo.";
        String pattern4 = name + " is in Echo but not in CodeExpert.";
        String pattern = "((" + pattern1 + ")|(" + pattern2 + ")|(" + pattern3 + ")|(" + pattern4 + "))";


        // Special case: A case with no misassigned students should produce no output
        if (expected.equals("")) {
            assertEquals("There should be no output if there are no misassigned students.", expected, actual);
        }

        // Check all lines
        for (int i = 0; i < actual_lines.size(); ++i) {

            if (expected_lines.get(i) != actual_lines.get(i)) {

                if (!actual_lines.get(i).matches(pattern)) {
                    // Line is malformed
                    assertEquals("Line " + i + " is malformed", expected_lines.get(i), actual_lines.get(i));
                }

                if (expected_lines.contains(actual_lines.get(i))) {
                    //Line is correct, but at wrong position
                    int expected_line = expected_lines.indexOf(actual_lines.get(i));
                    if (actual_lines.contains(expected_lines.get(i))) {
                        // Expected line for this position is there but at wrong position
                        assertEquals("Wrong order in output, " +
                                        "line " + i + " should be at position " + expected_line,
                                expected_lines.get(i), actual_lines.get(i));
                    } else {
                        // Expected line is missing
                        assertEquals("Missing output item on line " + i, expected_lines.get(i), actual_lines.get(i));
                    }
                } else {
                    // Line should not appear in output
                    assertEquals("Line " + i + " should not be part of output", expected_lines.get(i), actual_lines.get(i));
                }
            }

        }

    }

    /**
     * Verify that there was no output to System.err
     */
    static void checkErr() {
        assertEquals("There should be no output on err", "", errContent.toString());
    }

    /**
     * Redirect the output from the console to a Stream we can save
     */
    @Before
    public void setUpStreams() {
        outContent.reset();
        errContent.reset();
        System.setOut(new PrintStream(outContent));
        System.setErr(new PrintStream(errContent));
    }

    /**
     * Restore routing of output to the console
     */
    @After
    public void restoreStreams() {
        System.setOut(System.out);
        System.setErr(System.err);
    }

    /**
     * This test is simply here to workaround a Codeboard.io issue
     */
    @Test
    public void dummyTest() {
        // empty test passes
    }
}

Answer 1

這個file1.end來自哪里？

在您的main（）方法中：

據我了解，您想將一個文件的內容（逐行）與另一個文件進行比較。 您已經通過CSVReader類（ codeexpert [] []和echo [] [] ）將每個文件中的數據放入特定的2D字符串數組中。 現在，只需遍歷這些數組以查看它們是否不同（我假設您處理了CSV文件標題行，如果它們有一個的話）：

public static void main(String[] args) {
    /**
     * Read in "./Root/files/echo.csv" und "./Root/files/file1.csv"
     * and output the respective warning on System.out
     */
    String[][] codeexpert = CSVReader.readCSV("./Root/files/file1.csv");
    String[][] echo = CSVReader.readCSV("./Root/files/echo.csv");
    String msg = "The two files provided are not the same!";

    // See if the two arrays are of the same length.
    // This would be a dead give-away right from the start.
    if (codeexpert.length != echo.length) {
        System.err.println(msg);
        return;
    }

    // See if the lines in each file are the same. We check
    // the rows and columns of each 2D Array to do this.
    // Trap exceptions in case Array column indexing is different
    // on both 2D Arrays.
    try {
        // Get Row...
        for (int i = 0; i < codeexpert.length; i++) {
            // Get Coloumn...
            for (int j = 0; j < codeexpert[i].length; j++) {
                // Is the data in the columns of this particular row
                // the same in both arrays?
                if (!codeexpert[i][j].equals(echo[i][j])) {
                    // No it's not...  
                    System.err.println(msg);
                    return; 
                } 
            }
            System.out.println("File 1 - Line " + String.valueOf(i + 1) + ": " + Arrays.toString(codeexpert[i]));
            System.out.println("File 2 - Line " + String.valueOf(i + 1) + ": " + Arrays.toString(echo[i]));
        }
    } 
    catch (Exception ex) {
        // If the exception occurs then chances are the indexing
        // for columns is different on a particular row. 
        System.err.println(msg);
        return;
    }
    System.out.println("The two files are the same!");
}

編輯：Student.toString（）方法：

了解組件在每個文件行中的含義將很有幫助。 在創建toString（）方法或為Student類重載一個方法之前。

根據我從您的評論中收集到的信息，您正在嘗試將提供的逗號分隔文件行分隔為字符串數組，然后返回該數組。 我認為這是您應該做的（甜蜜和簡單）：

public static String[] toString(String inputString) {
    String[] s = inputString.split(",|,\\s+");
    return s;
}

這是您的學生班級怎么可能更適合：

public class Student {

    private String firstName;
    private String middleName;
    private String lastName;
    private String assignmentNumber;

    /**
     * The Student Class constructor that can optionally accept arguments. 
     * If a single argument is supplied and it consists of a comma (,) 
     * delimited CSV file line as a single string, that string will be 
     * split and the elements placed into the appropriate class fields.
     * If multiple arguments are supplied then it is assumed that those
     * string arguments represent the contents for our class field 
     * components which are assignmentNumber, lastName, middleName, and 
     * firstName (in that order). Of course if nothing is supplied this
     * is just an empty constructor.<br><br>
     * 
     * @param inputString (Optional - String) Read the above.
     */
    public Student (String... inputString) {
        String inString;
        if (inputString.length > 0) {
            // Single file line assumed...
            if (inputString.length == 1) {
                inString = inputString[0]; 
                if (!inString.equals("")) {
                    if (!inString.contains(",")) { 
                        throw new IllegalArgumentException("Student value can not be empty "
                                    + "OR Student value must be a comma delimited String!");
                    }
                    String[] values = inString.split(",|,\\s+");
                    if (values.length >= 1) { this.assignmentNumber = values[0]; }
                    else { this.assignmentNumber = ""; }
                    if (values.length >= 2) { this.lastName = values[1]; }
                    else { this.assignmentNumber = ""; }
                    if (values.length >= 3) { this.middleName = values[2]; }
                    else { this.middleName = ""; }
                    if (values.length >= 4) { this.firstName = values[3]; }
                    else { this.firstName = ""; }
                }
            }
            else {
                if (inputString.length >= 1) { this.assignmentNumber = inputString[0]; }
                if (inputString.length >= 2) { this.lastName = inputString[1]; }
                if (inputString.length >= 3) { this.middleName = inputString[2]; }
                if (inputString.length >= 4) { this.firstName = inputString[3]; }
            }
        }
    }

    /**
     * Overriden - Student.toString() method with no arguments to return a 
     * string like:  "17-995-364 Ruh Konrad Julia"
     * based from what is contained within the class fields.<br><br>
     * 
     * @return (String)
     */
    @Override
    public String toString() {
        String s = assignmentNumber + " " + lastName + " " + middleName + " " + firstName;
        return s;
    }


    /**
     * A static Student.toString() method that takes a string argument 
     * which is to be considered a single line of CSV file text. This
     * method will return a String Array containing elements which 
     * could look like this: [17-995-364, Ruh, Konrad, Julia]<br><br>
     * 
     * @param inputString (String) A single line of comma delimited CSV 
     * file text.<br>
     * 
     * @return (Single Dimensional String Array) 1D String Array containing 
     * specific elements from the supplied comma delimited CSV file line.
     */
    public static String[] toString(String inputString) {
        String[] s = inputString.split(",|,\\s+");
        return s;
    }

    /**
     * A Overloaded static Student.toString() method that takes a String Array
     * argument which is to be considered a single line of CSV file 
     * text that is split to create that array. This method will 
     * return a String containing which could look like this:<br><br> 
     * "17-995-364 Ruh Konrad Julia"<br><br>
     * 
     * @param inputArray (Single Dimensional String Array)<br>
     * 
     * @return (String) See Above...
     */
    public static String toString(String[] inputArray) {
        String s = "";
        for (String inputArray1 : inputArray) {
            s += s.equals("") ? inputArray1 : " " + inputArray1;
        }
        return s;
    }

    // Field Getters And Setters to enhance the class
    // for better usability.
    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getMiddleName() {
        return middleName;
    }

    public void setMiddleName(String middleName) {
        this.middleName = middleName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getAssignmentNumber() {
        return assignmentNumber;
    }

    public void setAssignmentNumber(String assignmentNumber) {
        this.assignmentNumber = assignmentNumber;
    }

}

當然，這一切都沒有經過真正的測試，我真的不知道您的項目的總體目標是什么，但總的來說，您可能會（或可能不會）從中受益。

Answer 2

我被告知，CSVreader應該是這樣的：

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;

/**
 * Diese Klasse liest eine *.csv Datei ein.
 * Wie das intern genau funktioniert ist fuer die Uebung nicht relevant
 */
public class CSVReader {

    /**
     * Diese Methode liest eine *.csv Datei ein und
     * speichert die einzelnen Eintraege als Elemente
     * eines zweidimensionalen Arrays.
     *
     * @param filename Pfad zur Datei, z.b. ".Root/test/echo.csv"
     * @return {@code String[][] s}  Wobei {@code s[i][j]} Der j-te Wert in der i-ten Zeile ist
     */
    public String[][] readCSV(String filename) {
        ArrayList<String[]> result = new ArrayList<>();

        BufferedReader br = null;
        String line = "";
        String cvsSplitBy = ",";

        try {
            br = new BufferedReader(new FileReader(filename));
            while ((line = br.readLine()) != null) {
                result.add(line.split(cvsSplitBy));
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return result.toArray(new String[result.size()][]);
    }
}

在主類中，我應該使用以下代碼：

String[][] dataEcho = new CSVReader().readCSV("./Root/files/echo.csv");<br>
String[][] dataCodeExpert = new CSVReader().readCSV("./Root/files/codeexpert.csv");