97 Things Every Java Programmer Should Know

Chapter 49. Kotlin Is a Thing

Mike Dunn

Java is maybe the most mature and vetted language still in common use, and that is unlikely to change dramatically in the foreseeable future. To facilitate modern notions of what a programming language should do, some smart folks decided to write a new language that did all the Java Things, plus some cool new Things that would be fairly painless to learn and be largely interoperable. Someone like me, who’s been working on the same huge Android app for years, can decide to write a single class in Kotlin without committing to a complete migration.

Kotlin is meant to let you write shorter, cleaner, more modern code. While modern and preview versions of Java do address a lot of the issues Kotlin manages, Kotlin can be especially useful for Android developers, who are stuck somewhere between Java 7 and Java 8.

Let’s look at a few examples, like Kotlin’s property constructor pattern for models, starting with a simple example of what a Java model may look like:

public class Person {
  private String name;
  private Integer age;
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public Integer getAge() {
    return age;
  }
  public void setAge(int age) {
    this.age = age;
  }
}

We could create a special constructor to take some initial values:

 public class Person { public Person(String name, Integer age) { this.name ...