SequenceInputStream changes (#11590)

Co-authored-by: Seshu Thanneeru <seshukumar.thanneeru@thoughtdata.com>

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

@@ -0,0 +1,45 @@
+package com.baeldung.iostreams;
+
+import java.io.*;
+import java.util.List;
+import java.util.Vector;
+
+public class InputSequenceHandler {
+
+    private SequenceInputStream sequenceInputStream;
+
+    public InputSequenceHandler(Vector<InputStream> inputStreams) {
+        sequenceInputStream = new SequenceInputStream(inputStreams.elements());
+    }
+
+    public InputSequenceHandler(String file1, String file2) throws FileNotFoundException {
+        sequenceInputStream = new SequenceInputStream(new FileInputStream(file1), new FileInputStream(file2));
+    }
+
+    public InputSequenceHandler(List<String> fileNames) throws FileNotFoundException {
+        Vector<InputStream> inputStreams = new Vector<>();
+
+        for (String fileName: fileNames) {
+            inputStreams.add(new FileInputStream(fileName));
+        }
+        sequenceInputStream = new SequenceInputStream(inputStreams.elements());
+    }
+
+
+    public int read() throws IOException {
+        return sequenceInputStream.read();
+    }
+
+    public String readAsString() throws IOException {
+        StringBuilder stringBuilder = new StringBuilder();
+        int readByte;
+        while ((readByte = sequenceInputStream.read()) != -1) {
+            stringBuilder.append((char) readByte);
+        }
+        return stringBuilder.toString();
+    }
+
+    public void close() throws IOException {
+        sequenceInputStream.close();
+    }
+}

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

@@ -0,0 +1,77 @@
+package com.baeldung.iostreams;
+
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.SequenceInputStream;
+import java.net.URISyntaxException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Vector;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class InputSequenceUnitTest {
+
+    private static final String FILE1 = "iostreams/File1.txt";
+    private static final String FILE2 = "iostreams/File2.txt";
+    private static final String FILE3 = "iostreams/File3.txt";
+
+    private static final String FILE1_AND_FILE2_CONTENT = "InputSequenceUnitTest";
+    private static final String ALL_FILES_CONTENT = "InputSequenceUnitTest is Success";
+
+    @Test
+    public void givenTwoFiles_readAsString() throws URISyntaxException, IOException {
+        String file1 = Paths.get(ClassLoader.getSystemResource(FILE1).toURI()).toString();
+        String file2 = Paths.get(ClassLoader.getSystemResource(FILE2).toURI()).toString();
+        InputSequenceHandler inputSequenceHandler = new InputSequenceHandler(file1, file2);
+        String stringValue = inputSequenceHandler.readAsString();
+        inputSequenceHandler.close();
+        assertEquals(stringValue, FILE1_AND_FILE2_CONTENT);
+    }
+
+    @Test
+    public void givenFileList_readAsString() throws URISyntaxException, IOException {
+        List<String> filesList = new ArrayList<>();
+        filesList.add(Paths.get(ClassLoader.getSystemResource(FILE1).toURI()).toString());
+        filesList.add(Paths.get(ClassLoader.getSystemResource(FILE2).toURI()).toString());
+        filesList.add(Paths.get(ClassLoader.getSystemResource(FILE3).toURI()).toString());
+        InputSequenceHandler inputSequenceHandler = new InputSequenceHandler(filesList);
+        String stringValue = inputSequenceHandler.readAsString();
+        inputSequenceHandler.close();
+        assertEquals(stringValue, ALL_FILES_CONTENT);
+    }
+
+    @Test
+    public void givenVectorOfInputStreams_readAsString() throws IOException {
+        String[] strings = {"Testing", "Leads", "to", "failure",
+                "and", "failure", "leads", "to", "understanding"};
+        Vector<InputStream> inputStreamVector = new Vector<>();
+        StringBuilder stringBuilder = new StringBuilder();
+        for (String string: strings) {
+            inputStreamVector.add(new ByteArrayInputStream(string.getBytes(StandardCharsets.UTF_8)));
+            stringBuilder.append(string);
+        }
+        InputSequenceHandler inputSequenceHandler = new InputSequenceHandler(inputStreamVector);
+        String combinedString = inputSequenceHandler.readAsString();
+        inputSequenceHandler.close();
+        assertEquals(stringBuilder.toString(), combinedString);
+    }
+
+    @Test
+    public void givenTwoStrings_readCombinedValue() throws IOException {
+        InputStream first = new ByteArrayInputStream("One".getBytes());
+        InputStream second = new ByteArrayInputStream("Magic".getBytes());
+        SequenceInputStream sequenceInputStream = new SequenceInputStream(first, second);
+        StringBuilder stringBuilder = new StringBuilder();
+        int byteValue;
+        while ((byteValue = sequenceInputStream.read()) != -1) {
+            stringBuilder.append((char) byteValue);
+        }
+        assertEquals("OneMagic", stringBuilder.toString());
+    }
+}

core-java-modules/core-java-io-4/src/test/resources/iostreams/File1.txt

@@ -0,0 +1 @@
+InputSequence

core-java-modules/core-java-io-4/src/test/resources/iostreams/File2.txt

@@ -0,0 +1 @@
+UnitTest

core-java-modules/core-java-io-4/src/test/resources/iostreams/File3.txt

@@ -0,0 +1 @@
+ is Success