BAEL-5822 printstream vs printwriter (#13199)

* BAEL-5822 pr with streams implementation, unit test and resource file for testing

* fix unit tests names

* swap arguments in assertion

Co-authored-by: Christian Jaimes <christian.jaimes@oracle>

core-java-modules/core-java-io-4/src/main/java/com/baeldung/iostreams/DataStream.java

@@ -0,0 +1,37 @@
+package com.baeldung.iostreams;
+
+import java.io.*;
+
+public class DataStream {
+    public static void textDataProcessingByteStream(String fileName, String content) throws IOException {
+        PrintStream out = new PrintStream(fileName);
+        out.print(content);
+        out.flush();
+    }
+
+    public static void textDataProcessingCharStream(String fileName, String content) throws IOException {
+        PrintWriter out = new PrintWriter(fileName);
+        out.print(content);
+        out.flush();
+    }
+
+    public static void nonTextDataProcessing(String fileName, String streamOutputFile, String writerOutputFile) throws IOException {
+        FileInputStream inputStream = new FileInputStream(fileName);
+        PrintStream printStream = new PrintStream(streamOutputFile);
+
+        int b;
+        while ((b = inputStream.read()) != -1) {
+            printStream.write(b);
+        }
+        printStream.close();
+
+        FileReader reader = new FileReader(fileName);
+        PrintWriter writer = new PrintWriter(writerOutputFile);
+
+        int c;
+        while ((c = reader.read()) != -1) {
+            writer.write(c);
+        }
+        writer.close();
+    }
+}

core-java-modules/core-java-io-4/src/test/java/com/baeldung/iostreams/DataStreamUnitTest.java

@@ -0,0 +1,66 @@
+package com.baeldung.iostreams;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class DataStreamUnitTest {
+
+    private static final String dataProcessingTextFile = "src/test/resources/iostreams/TestFile.txt";
+    private static final String dataProcessingImageFile = "src/test/resources/iostreams/image.png";
+    private static final String dataProcessingByteStreamFile = "src/test/resources/iostreams/ps.png";
+    private static final String dataProcessingCharStreamFile = "src/test/resources/iostreams/pw.png";
+
+    private static final String textFileContent = "Hello, world!";
+
+    @Test
+    public void whenUsingByteStream_thenWriteTextToFile() throws IOException {
+        DataStream dataStream = new DataStream();
+        dataStream.textDataProcessingByteStream(dataProcessingTextFile, textFileContent);
+
+        File file = new File(dataProcessingTextFile);
+        assertTrue(file.exists());
+        assertEquals(textFileContent, FileUtils.readFileToString(file, "utf-8"));
+
+        Files.delete(Paths.get(dataProcessingTextFile));
+    }
+
+    @Test
+    public void whenUsingCharStream_thenWriteTextToFile() throws IOException {
+        DataStream dataStream = new DataStream();
+        dataStream.textDataProcessingCharStream(dataProcessingTextFile, textFileContent);
+
+        File file = new File(dataProcessingTextFile);
+        assertTrue(file.exists());
+        assertEquals(textFileContent, FileUtils.readFileToString(file, "utf-8"));
+
+        Files.delete(Paths.get(dataProcessingTextFile));
+    }
+
+    @Test
+    public void whenUsingStreams_thenWriteNonTextData() throws IOException {
+        DataStream dataStream = new DataStream();
+        dataStream.nonTextDataProcessing(dataProcessingImageFile, dataProcessingByteStreamFile, dataProcessingCharStreamFile);
+
+        File file = new File(dataProcessingImageFile);
+        File byteStreamOutputFile = new File(dataProcessingByteStreamFile);
+        File charStreamOutputFile = new File(dataProcessingCharStreamFile);
+        assertTrue(file.exists());
+        assertTrue(byteStreamOutputFile.exists());
+        assertTrue(charStreamOutputFile.exists());
+
+        assertTrue(FileUtils.contentEquals(file, byteStreamOutputFile));
+        assertFalse(FileUtils.contentEquals(file, charStreamOutputFile));
+
+        Files.delete(Paths.get(dataProcessingByteStreamFile));
+        Files.delete(Paths.get(dataProcessingCharStreamFile));
+    }
+}