read user input (#11946)

* read user input

* rename the unittest class

core-java-modules/core-java-io-4/src/main/java/com/baeldung/userinput/UserInputHandler.java

@@ -0,0 +1,27 @@
+package com.baeldung.userinput;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class UserInputHandler {
+
+    public static List<String> readUserInput() {
+        List<String> userData = new ArrayList<>();
+        System.out.println("Please enter your data below: (send 'bye' to exit) ");
+        Scanner input = new Scanner(System.in);
+        while (true) {
+            String line = input.nextLine();
+            if ("bye".equalsIgnoreCase(line)) {
+                break;
+            }
+            userData.add(line);
+        }
+        return userData;
+    }
+
+    public static void main(String[] args) {
+        List<String> userData = readUserInput();
+        System.out.printf("User Input Data:\n%s", String.join("\n", userData));
+    }
+}

core-java-modules/core-java-io-4/src/test/java/com/baeldung/userinput/UserInputHandlerUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.userinput;
+
+
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class UserInputHandlerUnitTest {
+
+    @Test
+    public void givenDataInSystemIn_whenCallingReadUserInputMethod_thenHaveUserInputData() {
+        String[] inputLines = new String[]{
+            "The first line.",
+            "The second line.",
+            "The last line.",
+            "bye",
+            "anything after 'bye' will be ignored"
+        };
+        String[] expectedLines = Arrays.copyOf(inputLines, inputLines.length - 2);
+        List<String> expected = Arrays.stream(expectedLines).collect(Collectors.toList());
+        InputStream stdin = System.in;
+        try {
+            System.setIn(new ByteArrayInputStream(String.join("\n", inputLines).getBytes()));
+            List<String> actual = UserInputHandler.readUserInput();
+            assertThat(actual).isEqualTo(expected);
+        } finally {
+            System.setIn(stdin);
+        }
+    }
+}