brew install gradle

==> Downloading https://services.gradle.org/distributions/gradle-4.10.2-all.zip
==> Downloading from https://downloads.gradle.org/distributions/gradle-4.10.2-all.zip
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🍺  /usr/local/Cellar/gradle/4.10.2: 203 files, 83.7MB, built in 3 minutes 51 seconds

------------------------------------------------------------
Gradle 4.10.2
------------------------------------------------------------

Build time:   2018-09-19 18:10:15 UTC
Revision:     b4d8d5d170bb4ba516e88d7fe5647e2323d791dd

Kotlin DSL:   1.0-rc-6
Kotlin:       1.2.61
Groovy:       2.4.15
Ant:          Apache Ant(TM) version 1.9.11 compiled on March 23 2018
JVM:          1.8.0-adoptopenjdk (Oracle Corporation 25.71-b00)
OS:           Mac OS X 10.11.3 x86_64

gradle init --type java-application

Starting a Gradle Daemon, 10 busy Daemons could not be reused, use --status for details

BUILD SUCCESSFUL in 1s
2 actionable tasks: 2 executed

.
.
├── build.gradle
├── gradle
│   └── wrapper
│       ├── gradle-wrapper.jar
│       └── gradle-wrapper.properties
├── gradlew
├── gradlew.bat
├── settings.gradle
└── src
    ├── main
    │   └── java
    │       └── App.java
    └── test
        └── java
            └── AppTest.java

./gradlew build

BUILD SUCCESSFUL in 52s
4 actionable tasks: 4 executed

./gradlew run

/*
 * This Java source file was generated by the Gradle 'init' task.
 */

public class App {
    public String getGreeting() {
        return "Hello world.";
    }

    public static void main(String[] args) {
        System.out.println(new App().getGreeting());
    }
}

> Task :run
Hello world.

BUILD SUCCESSFUL in 1s
2 actionable tasks: 1 executed, 1 up-to-date

/*
 * This Java source file was generated by the Gradle 'init' task.
 */
import org.junit.Test;
import static org.junit.Assert.*;

public class AppTest {
    @Test public void testAppHasAGreeting() {
        App classUnderTest = new App();
        assertNotNull("app should have a greeting", classUnderTest.getGreeting());// Nullを返せばNGになりそう
    }
}

/*
 * This Java source file was generated by the Gradle 'init' task.
 */
public class App {
    public String getGreeting() {
        //return "Hello world.";
        return null;
    }

    public static void main(String[] args) {
        System.out.println(new App().getGreeting());
    }
}

> Task :test FAILED

AppTest > testAppHasAGreeting FAILED
    java.lang.AssertionError at AppTest.java:10

1 test completed, 1 failed

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':test'.
> There were failing tests. See the report at: file:///Users/blogenist/tmp/work/java/gradleSample/build/reports/tests/test/index.html

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s
7 actionable tasks: 5 executed, 2 up-to-date

dependencies {
    // This dependency is found on compile classpath of this component and consumers.
    compile 'com.google.guava:guava:23.0'
    compile "com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.9.7" // 追加

    // Use JUnit test framework
    testCompile 'junit:junit:4.12'
}

/*
 * This Java source file was generated by the Gradle 'init' task.
 */
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.core.JsonProcessingException;

public class App {
    public String getGreeting() {
        return "Hello world.";
    }

    public static void main(String[] args) throws JsonProcessingException {
      ObjectMapper objectMapper = new ObjectMapper();;

      Person taro = new Person("taro", 25);

      String jsonString = objectMapper.writeValueAsString(taro);
      System.out.println(jsonString);
    }

    public static class Person{
      private String name;
      private int age;

      public Person(String name, int age){
        this.name = name;
        this.age = age;
      }
      public String getName(){
        return name;
      }

      public int getAge(){
        return age;
      }
    }
}

./gradlew run

> Task :run
{"name":"taro","age":25}

BUILD SUCCESSFUL in 1s
2 actionable tasks: 2 executed