Add 'Counting the Number of Characters' solution

Non-GUI version

Author: durimkryeziu

characters-count/build.gradle

@@ -0,0 +1,17 @@
+plugins {
+    id 'java'
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation(libs.assertj.core)
+    testImplementation(libs.junit.jupiter)
+    testRuntimeOnly(libs.junit.platform.launcher)
+}
+
+tasks.named('test') {
+    useJUnitPlatform()
+}

characters-count/src/main/java/com/craftsmanshipinsoftware/count/CharactersCounter.java

@@ -0,0 +1,40 @@
+package com.craftsmanshipinsoftware.count;
+
+import java.io.InputStream;
+import java.io.PrintStream;
+import java.util.Objects;
+import java.util.Scanner;
+
+public class CharactersCounter {
+
+  private final InputStream inputStream;
+  private final PrintStream printStream;
+
+  public CharactersCounter(InputStream inputStream, PrintStream printStream) {
+    Objects.requireNonNull(inputStream, "inputStream must not be null");
+    Objects.requireNonNull(printStream, "printStream must not be null");
+    this.inputStream = inputStream;
+    this.printStream = printStream;
+  }
+
+  public void displayCharactersCount() {
+    askForInput();
+    String input = readInput();
+    if (input == null || input.isBlank()) {
+      this.printStream.println("Please enter something as input!");
+      return;
+    }
+    this.printStream.printf("%s has %d characters.%n", input, input.length());
+  }
+
+  private void askForInput() {
+    System.out.print("What is the input string? ");
+  }
+
+  private String readInput() {
+    try (Scanner scanner = new Scanner(this.inputStream)) {
+      return scanner.hasNext() ? scanner.nextLine() : null;
+    }
+  }
+
+}

characters-count/src/main/java/com/craftsmanshipinsoftware/count/Main.java

@@ -0,0 +1,9 @@
+package com.craftsmanshipinsoftware.count;
+
+public class Main {
+
+  public static void main(String[] args) {
+    CharactersCounter charactersCounter = new CharactersCounter(System.in, System.out);
+    charactersCounter.displayCharactersCount();
+  }
+}

characters-count/src/test/java/com/craftsmanshipinsoftware/count/CharactersCounterTests.java

@@ -0,0 +1,32 @@
+package com.craftsmanshipinsoftware.count;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import org.junit.jupiter.api.Test;
+
+class CharactersCounterTests {
+
+  @Test
+  void displayCharactersCount_GivenNoInput_ShouldAskToInputSomething() {
+    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+    CharactersCounter charactersCounter = new CharactersCounter(new ByteArrayInputStream(new byte[]{}), new PrintStream(outputStream));
+
+    charactersCounter.displayCharactersCount();
+
+    assertThat(outputStream).hasToString("Please enter something as input!" + System.lineSeparator());
+  }
+
+  @Test
+  void displayCharactersCount_GivenValidInput_ShouldDisplayCharactersCount() {
+    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+    CharactersCounter charactersCounter = new CharactersCounter(new ByteArrayInputStream("Durim".getBytes()), new PrintStream(outputStream));
+
+    charactersCounter.displayCharactersCount();
+
+    assertThat(outputStream).hasToString("Durim has 5 characters." + System.lineSeparator());
+  }
+
+}

settings.gradle

@@ -1,2 +1,2 @@
 rootProject.name = 'exercises-for-programmers-java'
-include('saying-hello')
+include('saying-hello', 'characters-count')