This commit is related to BAEL-6873 (#15579)

This commit aims to add a class "ReadInputCharByChar" that provides several approaches to read input char by char.

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/readinputcharbychar/ReadInputCharByCharUnitTest.java

@@ -0,0 +1,59 @@
+package com.baeldung.readinputcharbychar;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.*;
+import java.util.Scanner;
+
+import static org.junit.Assert.assertArrayEquals;
+
+public class ReadInputCharByCharUnitTest {
+
+    @Test
+    public void givenInputFromConsole_whenUsingBufferedStream_thenReadCharByChar() throws IOException {
+        ByteArrayInputStream inputStream = new ByteArrayInputStream("TestInput".getBytes());
+        System.setIn(inputStream);
+
+        try (BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in))) {
+            char[] result = new char[9];
+            int index = 0;
+            int c;
+            while ((c = buffer.read()) != -1) {
+                result[index++] = (char) c;
+            }
+
+            assertArrayEquals("TestInput".toCharArray(), result);
+        }
+    }
+
+    @Test
+    public void givenInputFromFile_whenUsingFileReader_thenReadCharByChar() throws IOException {
+        File tempFile = File.createTempFile("tempTestFile", ".txt");
+        FileWriter fileWriter = new FileWriter(tempFile);
+        fileWriter.write("TestFileContent");
+        fileWriter.close();
+
+        try (FileReader fileReader = new FileReader(tempFile.getAbsolutePath())) {
+            char[] result = new char[15]; // Adjust the size based on your input
+            int index = 0;
+            int charCode;
+            while ((charCode = fileReader.read()) != -1) {
+                result[index++] = (char) charCode;
+            }
+
+            assertArrayEquals("TestFileContent".toCharArray(), result);
+        }
+    }
+
+    @Test
+    public void givenInputFromConsole_whenUsingScanner_thenReadCharByChar() {
+        ByteArrayInputStream inputStream = new ByteArrayInputStream("TestInput".getBytes());
+        System.setIn(inputStream);
+
+        try (Scanner scanner = new Scanner(System.in)) {
+            char[] result = scanner.next().toCharArray();
+
+            assertArrayEquals("TestInput".toCharArray(), result);
+        }
+    }
+}