Merge pull request #15809 from anujgaud/system-in-read

[BAEL-7405] Add support for System read methods

core-java-modules/core-java-console/src/main/java/com/baeldung/systemin/SystemInRead.java

@@ -0,0 +1,45 @@
+package com.baeldung.systemin;
+
+import java.io.IOException;
+
+class SystemInRead {
+    static void readSingleCharacter() {
+        System.out.println("Enter a character:");
+        try {
+            int input = System.in.read();
+            System.out.println((char) input);
+        }
+        catch (IOException e) {
+            System.err.println("Error reading input: " + e.getMessage());
+        }
+    }
+    static void readMultipleCharacters() {
+        System.out.println("Enter characters (Press 'Enter' to quit):");
+        try {
+            int input;
+            while ((input = System.in.read()) != '\n') {
+                System.out.print((char) input);
+            }
+        } catch (IOException e) {
+            System.err.println("Error reading input: " + e.getMessage());
+        }
+    }
+
+    static void readWithParameters() {
+        try {
+            byte[] byteArray = new byte[5];
+            int bytesRead;
+            int totalBytesRead = 0;
+
+            while ((bytesRead = System.in.read(byteArray, 0, byteArray.length)) != -1) {
+                System.out.print("Data read: " + new String(byteArray, 0, bytesRead));
+                totalBytesRead += bytesRead;
+            }
+
+            System.out.println("\nBytes Read: " + totalBytesRead);
+
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}

core-java-modules/core-java-console/src/test/java/com/baeldung/systemin/SystemInReadUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.systemin;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+
+import org.junit.jupiter.api.Test;
+
+public class SystemInReadUnitTest {
+    @Test
+    void givenUserInput_whenUsingReadMultipleCharacters_thenRead() {
+        System.setIn(new ByteArrayInputStream("Hello\n".getBytes()));
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        System.setOut(new PrintStream(outputStream));
+        SystemInRead.readMultipleCharacters();
+
+        assertEquals("Enter characters (Press 'Enter' to quit):\n" + "Hello", outputStream.toString().trim());
+    }
+
+    @Test
+    void givenUserInput_whenUsingReadSingleCharacter_thenRead() {
+        System.setIn(new ByteArrayInputStream("A".getBytes()));
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        System.setOut(new PrintStream(outputStream));
+        SystemInRead.readSingleCharacter();
+
+        assertEquals("Enter a character:\nA", outputStream.toString().trim());
+    }
+
+    @Test
+    void givenUserInput_whenUsingReadWithParameters_thenRead() {
+        System.setIn(new ByteArrayInputStream("ABC".getBytes()));
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        System.setOut(new PrintStream(outputStream));
+        SystemInRead.readWithParameters();
+
+        assertEquals("Data read: ABC\n" + "Bytes Read: 3", outputStream.toString().trim());
+    }
+}