Merge pull request #12456 from hkhan/JAVA-12757-update-opencsv-code

[JAVA-12757] Update code for OpenCSV article

libraries-data-io/src/main/java/com/baeldung/libraries/opencsv/Application.java

@@ -1,5 +1,6 @@
 package com.baeldung.libraries.opencsv;
 
+import com.baeldung.libraries.opencsv.beans.CsvBean;
 import com.baeldung.libraries.opencsv.beans.NamedColumnBean;
 import com.baeldung.libraries.opencsv.beans.SimplePositionBean;
 import com.baeldung.libraries.opencsv.examples.sync.BeanExamples;
@@ -7,102 +8,60 @@ import com.baeldung.libraries.opencsv.examples.sync.CsvReaderExamples;
 import com.baeldung.libraries.opencsv.examples.sync.CsvWriterExamples;
 import com.baeldung.libraries.opencsv.helpers.Helpers;
 
-import java.io.Reader;
-import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.List;
 
 public class Application {
 
-        /*
+    // CSV Reader Examples
-         *  Bean Examples.
+    public static List<String[]> readLineByLineSyncExample() throws Exception {
-         */
+        Path path = Helpers.twoColumnCsvPath();
-
+        return CsvReaderExamples.readLineByLine(path);
-    public static String simpleSyncPositionBeanExample() {
-        Path path = null;
-        try {
-            path = Helpers.twoColumnCsvPath();
-        } catch (Exception ex) {
-            Helpers.err(ex);
-        }
-        return BeanExamples.beanBuilderExample(path, SimplePositionBean.class).toString();
     }
 
-    public static String namedSyncColumnBeanExample() {
+    public static List<String[]> readAllLinesSyncExample() throws Exception {
-        Path path = null;
+        Path path = Helpers.twoColumnCsvPath();
-        try {
+        return CsvReaderExamples.readAllLines(path);
-            path = Helpers.namedColumnCsvPath();
-        } catch (Exception ex) {
-            Helpers.err(ex);
-        }
-        return BeanExamples.beanBuilderExample(path, NamedColumnBean.class).toString();
     }
 
-    public static String writeSyncCsvFromBeanExample() {
+    // CSV Writer Examples
-        Path path = null;
+    public static String writeLineByLineSyncExample() throws Exception {
-        try {
+        Path path = Helpers.fileOutOnePath();
-            path = Helpers.fileOutBeanPath();
+        return CsvWriterExamples.writeLineByLine(Helpers.fourColumnCsvString(), path);
-        } catch (Exception ex) {
-            Helpers.err(ex);
     }
+
+    public static String writeAllLinesSyncExample() throws Exception {
+        Path path = Helpers.fileOutAllPath();
+        return CsvWriterExamples.writeAllLines(Helpers.fourColumnCsvString(), path);
+    }
+
+    // Bean Examples
+    public static List<CsvBean> simpleSyncPositionBeanExample() throws Exception {
+        Path path = Helpers.twoColumnCsvPath();
+        return BeanExamples.beanBuilderExample(path, SimplePositionBean.class);
+    }
+
+    public static List<CsvBean> namedSyncColumnBeanExample() throws Exception {
+        Path path = Helpers.namedColumnCsvPath();
+        return BeanExamples.beanBuilderExample(path, NamedColumnBean.class);
+    }
+
+    public static String writeSyncCsvFromBeanExample() throws Exception {
+        Path path = Helpers.fileOutBeanPath();
         return BeanExamples.writeCsvFromBean(path);
     }
 
-        /*
-         *  CSV Reader Examples.
-         */
-
-    public static String oneByOneSyncExample() {
-        Reader reader = null;
-        try {
-            reader = Files.newBufferedReader(Helpers.twoColumnCsvPath());
-        } catch (Exception ex) {
-            Helpers.err(ex);
-        }
-        return CsvReaderExamples.oneByOne(reader).toString();
-    }
-
-    public static String readAllSyncExample() {
-        Reader reader = null;
-        try {
-            reader = Files.newBufferedReader(Helpers.twoColumnCsvPath());
-        } catch (Exception ex) {
-            Helpers.err(ex);
-        }
-        return CsvReaderExamples.readAll(reader).toString();
-    }
-
-         /*
-         *  CSV Writer Examples.
-         */
-
-
-    public static String csvWriterSyncOneByOne() {
-        Path path = null;
-        try {
-            path = Helpers.fileOutOnePath();
-        } catch (Exception ex) {
-            Helpers.err(ex);
-        }
-        return CsvWriterExamples.csvWriterOneByOne(Helpers.fourColumnCsvString(), path);
-    }
-
-    public static String csvWriterSyncAll() {
-        Path path = null;
-        try {
-            path = Helpers.fileOutAllPath();
-        } catch (Exception ex) {
-            Helpers.err(ex);
-        }
-        return CsvWriterExamples.csvWriterAll(Helpers.fourColumnCsvString(), path);
-    }
-
     public static void main(String[] args) {
+        try {
             simpleSyncPositionBeanExample();
             namedSyncColumnBeanExample();
             writeSyncCsvFromBeanExample();
-        oneByOneSyncExample();
+            readLineByLineSyncExample();
-        readAllSyncExample();
+            readAllLinesSyncExample();
-        csvWriterSyncOneByOne();
+            writeLineByLineSyncExample();
-        csvWriterSyncAll();
+            writeAllLinesSyncExample();
+        } catch (Exception e) {
+            throw new RuntimeException("Error during csv processing", e);
+        }
     }
 }

libraries-data-io/src/main/java/com/baeldung/libraries/opencsv/beans/NamedColumnBean.java

@@ -27,5 +27,10 @@ public class NamedColumnBean extends CsvBean {
         this.age = age;
     }
 
+    @Override
+    public String toString() {
+        return name + ',' + age;
+    }
+
 
 }

libraries-data-io/src/main/java/com/baeldung/libraries/opencsv/beans/SimplePositionBean.java

@@ -26,4 +26,8 @@ public class SimplePositionBean extends CsvBean {
         this.exampleColTwo = exampleColTwo;
     }
 
+    @Override
+    public String toString() {
+        return exampleColOne + ',' + exampleColTwo;
+    }
 }

libraries-data-io/src/main/java/com/baeldung/libraries/opencsv/beans/WriteExampleBean.java

@@ -37,4 +37,9 @@ public class WriteExampleBean extends CsvBean {
     public void setColC(String colC) {
         this.colC = colC;
     }
+
+    @Override
+    public String toString() {
+        return colA + ',' + colB + "," + colC;
+    }
 }

libraries-data-io/src/main/java/com/baeldung/libraries/opencsv/examples/sync/BeanExamples.java

@@ -4,60 +4,49 @@ import com.baeldung.libraries.opencsv.beans.CsvBean;
 import com.baeldung.libraries.opencsv.beans.WriteExampleBean;
 import com.baeldung.libraries.opencsv.helpers.Helpers;
 import com.baeldung.libraries.opencsv.pojos.CsvTransfer;
-import com.opencsv.CSVWriter;
+import com.opencsv.bean.CsvToBean;
-import com.opencsv.bean.*;
+import com.opencsv.bean.CsvToBeanBuilder;
+import com.opencsv.bean.StatefulBeanToCsv;
+import com.opencsv.bean.StatefulBeanToCsvBuilder;
 
 import java.io.FileWriter;
 import java.io.Reader;
 import java.io.Writer;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 public class BeanExamples {
 
-    public static List<CsvBean> beanBuilderExample(Path path, Class clazz) {
+    public static List<CsvBean> beanBuilderExample(Path path, Class<? extends CsvBean> clazz) throws Exception {
-        ColumnPositionMappingStrategy ms = new ColumnPositionMappingStrategy();
-        return beanBuilderExample(path, clazz, ms);
-    }
-
-    public static List<CsvBean> beanBuilderExample(Path path, Class clazz, MappingStrategy ms) {
         CsvTransfer csvTransfer = new CsvTransfer();
-        try {
+        try (Reader reader = Files.newBufferedReader(path)) {
-            ms.setType(clazz);
+            CsvToBean<CsvBean> cb = new CsvToBeanBuilder<CsvBean>(reader)
-
+              .withType(clazz)
-            Reader reader = Files.newBufferedReader(path);
-            CsvToBean cb = new CsvToBeanBuilder(reader).withType(clazz)
-                .withMappingStrategy(ms)
               .build();
 
             csvTransfer.setCsvList(cb.parse());
-            reader.close();
-
-        } catch (Exception ex) {
-            Helpers.err(ex);
         }
+
         return csvTransfer.getCsvList();
     }
 
-    public static String writeCsvFromBean(Path path) {
+    public static String writeCsvFromBean(Path path) throws Exception {
-        try {
-            Writer writer = new FileWriter(path.toString());
 
-            StatefulBeanToCsv sbc = new StatefulBeanToCsvBuilder(writer).withSeparator(CSVWriter.DEFAULT_SEPARATOR)
+        List<CsvBean> sampleData = Arrays.asList(
+            new WriteExampleBean("Test1", "sample", "data"),
+            new WriteExampleBean("Test2", "ipso", "facto")
+        );
+
+        try (Writer writer = new FileWriter(path.toString())) {
+            StatefulBeanToCsv<CsvBean> sbc = new StatefulBeanToCsvBuilder<CsvBean>(writer)
+              .withQuotechar('\'')
               .build();
 
-            List<CsvBean> list = new ArrayList<>();
+            sbc.write(sampleData);
-            list.add(new WriteExampleBean("Test1", "sfdsf", "fdfd"));
-            list.add(new WriteExampleBean("Test2", "ipso", "facto"));
-
-            sbc.write(list);
-            writer.close();
-
-        } catch (Exception ex) {
-            Helpers.err(ex);
         }
+
         return Helpers.readFile(path);
     }
 }

libraries-data-io/src/main/java/com/baeldung/libraries/opencsv/examples/sync/CsvReaderExamples.java

@@ -1,61 +1,58 @@
 package com.baeldung.libraries.opencsv.examples.sync;
 
-import com.baeldung.libraries.opencsv.helpers.Helpers;
 import com.opencsv.CSVParser;
 import com.opencsv.CSVParserBuilder;
 import com.opencsv.CSVReader;
 import com.opencsv.CSVReaderBuilder;
 
 import java.io.Reader;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
 
 public class CsvReaderExamples {
 
-    public static List<String[]> readAll(Reader reader) {
+    public static List<String[]> readAllLines(Path filePath) throws Exception {
 
         CSVParser parser = new CSVParserBuilder()
           .withSeparator(',')
           .withIgnoreQuotations(true)
           .build();
 
-        CSVReader csvReader = new CSVReaderBuilder(reader)
+        try (Reader reader = Files.newBufferedReader(filePath)) {
+            CSVReaderBuilder csvReaderBuilder = new CSVReaderBuilder(reader)
               .withSkipLines(0)
-                .withCSVParser(parser)
+              .withCSVParser(parser);
-                .build();
 
-        List<String[]> list = new ArrayList<>();
+            try (CSVReader csvReader = csvReaderBuilder.build()) {
-        try {
+                return csvReader.readAll();
-            list = csvReader.readAll();
-            reader.close();
-            csvReader.close();
-        } catch (Exception ex) {
-            Helpers.err(ex);
             }
-        return list;
         }
 
-    public static List<String[]> oneByOne(Reader reader) {
+    }
+
+    public static List<String[]> readLineByLine(Path filePath) throws Exception {
         List<String[]> list = new ArrayList<>();
-        try {
+
         CSVParser parser = new CSVParserBuilder()
           .withSeparator(',')
           .withIgnoreQuotations(true)
           .build();
 
-            CSVReader csvReader = new CSVReaderBuilder(reader)
+        try (Reader reader = Files.newBufferedReader(filePath)) {
-                    .withSkipLines(0)
-                    .withCSVParser(parser)
-                    .build();
 
+            CSVReaderBuilder csvReaderBuilder = new CSVReaderBuilder(reader)
+              .withSkipLines(0)
+              .withCSVParser(parser);
+
+            try (CSVReader csvReader = csvReaderBuilder.build()) {
                 String[] line;
                 while ((line = csvReader.readNext()) != null) {
                     list.add(line);
                 }
-            reader.close();
+            }
-            csvReader.close();
+
-        } catch (Exception ex) {
-            Helpers.err(ex);
         }
         return list;
     }

libraries-data-io/src/main/java/com/baeldung/libraries/opencsv/examples/sync/CsvWriterExamples.java

@@ -9,26 +9,21 @@ import java.util.List;
 
 public class CsvWriterExamples {
 
-    public static String csvWriterOneByOne(List<String[]> stringArray, Path path) {
+    public static String writeLineByLine(List<String[]> lines, Path path) throws Exception {
-        try {
+
-            CSVWriter writer = new CSVWriter(new FileWriter(path.toString()));
+        try (CSVWriter writer = new CSVWriter(new FileWriter(path.toString()))) {
-            for (String[] array : stringArray) {
+            for (String[] line : lines) {
-                writer.writeNext(array);
+                writer.writeNext(line);
             }
-            writer.close();
-        } catch (Exception ex) {
-            Helpers.err(ex);
         }
+
         return Helpers.readFile(path);
     }
 
-    public static String csvWriterAll(List<String[]> stringArray, Path path) {
+    public static String writeAllLines(List<String[]> lines, Path path) throws Exception {
-        try {
+
-            CSVWriter writer = new CSVWriter(new FileWriter(path.toString()));
+        try (CSVWriter writer = new CSVWriter(new FileWriter(path.toString()))) {
-            writer.writeAll(stringArray);
+            writer.writeAll(lines);
-            writer.close();
-        } catch (Exception ex) {
-            Helpers.err(ex);
         }
         return Helpers.readFile(path);
     }

libraries-data-io/src/main/java/com/baeldung/libraries/opencsv/helpers/Helpers.java

@@ -1,9 +1,9 @@
 package com.baeldung.libraries.opencsv.helpers;
 
 import com.baeldung.libraries.opencsv.Constants;
+import org.apache.commons.io.IOUtils;
 
-import java.io.BufferedReader;
+import java.io.IOException;
-import java.io.FileReader;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.file.Path;
@@ -13,9 +13,7 @@ import java.util.List;
 
 public class Helpers {
 
-    /**
+    // Write Files
-     * Write Files
-     */
 
     public static Path fileOutAllPath() throws URISyntaxException {
         URI uri = ClassLoader.getSystemResource(Constants.CSV_All).toURI();
@@ -32,9 +30,7 @@ public class Helpers {
         return Paths.get(uri);
     }
 
-    /**
+    // Read Files
-     * Read Files
-     */
 
     public static Path twoColumnCsvPath() throws URISyntaxException {
         URI uri = ClassLoader.getSystemResource(Constants.TWO_COLUMN_CSV).toURI();
@@ -51,33 +47,12 @@ public class Helpers {
         return Paths.get(uri);
     }
 
-    /**
+    public static String readFile(Path path) throws IOException {
-     * Simple File Reader
+        return IOUtils.toString(path.toUri());
-     */
-
-    public static String readFile(Path path) {
-        String response = "";
-        try {
-            FileReader fr = new FileReader(path.toString());
-            BufferedReader br = new BufferedReader(fr);
-            String strLine;
-            StringBuffer sb = new StringBuffer();
-            while ((strLine = br.readLine()) != null) {
-                sb.append(strLine);
-            }
-            response = sb.toString();
-            System.out.println(response);
-            fr.close();
-            br.close();
-        } catch (Exception ex) {
-            Helpers.err(ex);
-        }
-        return response;
     }
 
-    /**
+
-     * Dummy Data for Writing.
+    // Dummy Data for Writing
-     */
 
     public static List<String[]> twoColumnCsvString() {
         List<String[]> list = new ArrayList<>();
@@ -94,15 +69,4 @@ public class Helpers {
         return list;
     }
 
-    /**
-     * Message Helpers
-     */
-
-    public static void print(String msg) {
-        System.out.println(msg);
-    }
-
-    public static void err(Exception ex) {
-        System.out.println(Constants.GENERIC_EXCEPTION + " " + ex);
-    }
 }

libraries-data-io/src/main/resources/csv/twoColumn.csv

@@ -1,5 +1,5 @@
-colA, ColB
+colA,colB
-A, B
+A,B
-C, D
+C,D
-G, G
+G,G
-G, F
+G,F

libraries-data-io/src/test/java/com/baeldung/libraries/opencsv/OpenCsvIntegrationTest.java

@@ -1,66 +1,107 @@
 package com.baeldung.libraries.opencsv;
 
-import com.baeldung.libraries.opencsv.helpers.Helpers;
+import com.baeldung.libraries.opencsv.beans.CsvBean;
-import org.junit.After;
-import org.junit.Before;
 import org.junit.Test;
 
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
 public class OpenCsvIntegrationTest {
 
-    private Object testReadCsv(Object result) {
+    private static final String NEW_LINE = System.lineSeparator();
-        assert (result != null);
-        assert (result instanceof String);
-        assert (!((String) result).isEmpty());
-        System.out.println(result);
-        return result;
-    }
 
-    private Object testWriteCsv(Object result) {
+    @Test
-        assert (result instanceof String);
+    public void givenSampleData_whenReadUsingPosition_thenContentsRead() throws Exception {
-        assert (!((String) result).isEmpty());
+        List<CsvBean> values = Application.simpleSyncPositionBeanExample();
-        return result;
-    }
 
-    @Before
+        assertThat(values)
-    public void setup() {
+          .extracting(Object::toString)
+          .containsExactly(
+          "colA,colB",
+          "A,B",
+          "C,D",
+          "G,G",
+          "G,F"
+        );
     }
 
     @Test
-    public void positionExampleTest() {
+    public void givenSampleData_whenReadUsingNamedColumn_thenContentsRead() throws Exception {
-        testReadCsv(Application.simpleSyncPositionBeanExample());
+        List<CsvBean> values = Application.namedSyncColumnBeanExample();
+
+        assertThat(values)
+          .extracting(Object::toString)
+          .containsExactly(
+            "Joe,27",
+            "Jane,32",
+            "Bob,53"
+        );
     }
 
     @Test
-    public void namedColumnExampleTest() {
+    public void givenSampleData_whenReadLineByLine_thenContentsRead() throws Exception {
-        testReadCsv(Application.namedSyncColumnBeanExample());
+        List<String[]> lineByLineContents = Application.readLineByLineSyncExample();
+
+        assertThat(lineByLineContents)
+          .containsExactly(
+            new String[] {"colA", "colB"},
+            new String[] {"A", "B"},
+            new String[] {"C", "D"},
+            new String[] {"G", "G"},
+            new String[] {"G", "F"}
+          );
     }
 
     @Test
-    public void writeCsvUsingBeanBuilderTest() {
+    public void givenSampleData_whenReadAllLines_thenContentsRead() throws Exception {
-        testWriteCsv(Application.writeSyncCsvFromBeanExample());
+
+        List<String[]> contents = Application.readAllLinesSyncExample();
+
+        assertThat(contents)
+          .containsExactly(
+            new String[] {"colA", "colB"},
+            new String[] {"A", "B"},
+            new String[] {"C", "D"},
+            new String[] {"G", "G"},
+            new String[] {"G", "F"}
+          );
     }
 
     @Test
-    public void oneByOneExampleTest() {
+    public void givenSampleData_whenWriteCsvUsingBean_thenContentsWritten() throws Exception {
-        testReadCsv(Application.oneByOneSyncExample());
+        String contents = Application.writeSyncCsvFromBeanExample();
+
+        assertThat(contents.split(NEW_LINE))
+          .containsExactly(
+          "'colA','colB','colC'",
+          "'Test1','sample','data'",
+          "'Test2','ipso','facto'"
+        );
     }
 
     @Test
-    public void readAllExampleTest() {
+    public void givenSampleData_whenWriteCsvLineByLine_thenContentsWritten() throws Exception {
-        testReadCsv(Application.readAllSyncExample());
+        String contents = Application.writeLineByLineSyncExample();
+
+        assertThat(contents.split(NEW_LINE))
+          .containsExactly(
+            "\"ColA\",\"ColB\",\"ColC\",\"ColD\"",
+            "\"A\",\"B\",\"A\",\"B\"",
+            "\"BB\",\"AB\",\"AA\",\"B\""
+          );
     }
 
     @Test
-    public void csvWriterOneByOneTest() {
+    public void givenSampleData_whenWriteCsvAllLines_thenContentsWritten() throws Exception {
-        testWriteCsv(Application.csvWriterSyncOneByOne());
+        String contents = Application.writeAllLinesSyncExample();
+
+        assertThat(contents.split(NEW_LINE))
+          .containsExactly(
+            "\"ColA\",\"ColB\",\"ColC\",\"ColD\"",
+            "\"A\",\"B\",\"A\",\"B\"",
+            "\"BB\",\"AB\",\"AA\",\"B\""
+          );
     }
 
-    @Test
-    public void csvWriterAllTest() {
-        testWriteCsv(Application.csvWriterSyncAll());
-    }
-
-    @After
-    public void close() {
-    }
 }