我想读入两个文件并比较两个文件的每个元素。文件的所有行都是这样的： 17-995-364，Ruh，Konrad，Julia 我有两个班：
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的类没有完成，主类也没有：
/ ** * Java程序的主类。 * * /
public class Main {
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);
}
}
我想做一个sort函数，但在此之前，主类中的输出必须正确。目前我有编译错误。如果我得到像我想要的元素，sort函数对我来说不是问题。另外我应该使用Student类的toString函数。如何解决主类中的编译错误，方法readSCV是否正确？ 编译错误是：
编译错误是：
./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个错误
我需要这个：
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
}
}
答案 0 :(得分：0)
file1.end 来自哪里？
在您的main（）方法中：
据我了解，您希望将一个文件的内容（逐行）与另一个文件进行比较。您已经通过 CSVReader 类（ codeexpert [] [] 和 echo [] [] ）。现在这是迭代这些数组以查看它们是否不同的问题（我假设您处理了CSV文件标题行，如果有的话）：
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!");
}
编辑：Student.toString（）方法：
了解组件在每个文件行中的含义会很有帮助。在创建 toString（）方法或为学生类重载一个方法之前。
根据我从您的评论中收集的内容，您尝试将提供的逗号分隔文件行分隔为字符串数组，然后返回该数组。以下是我认为你应该这样做的方式（甜蜜和简单）：
public static String[] toString(String inputString) {
String[] s = inputString.split(",|,\\s+");
return s;
}
以下是学生班级 MIGHT 更适合的方式：
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;
}
}
当然，这些都没有真正经过测试，我真的不知道你的项目的总体目标是什么，但从来没有那么少，你可能（或可能不会）从中受益。
答案 1 :(得分：0)
我被告知，CSVreader应该是这样的：
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()][]);
}
}
在主要课程中我应该使用它：
String[][] dataEcho = new CSVReader().readCSV("./Root/files/echo.csv");<br>
String[][] dataCodeExpert = new CSVReader().readCSV("./Root/files/codeexpert.csv");