[Kotlin] Using Kotlin from Java

Create a Kotlin class:

package com.rsk.kotlin

class Meeting(val title: String) {
    // in Java, you can use getLocation and setLocation
    var location = ""
    // you cannnot directly use m.description = 'xxx' or System.out.println(m.description)
    // you have to add @JvmField, so that in Java we can access as a property
    @JvmField
    var description = ""

    //  This class might throw exception
    @Throws(MeetingException::class)
    fun addAttendee(attendee: String) {
        if (attendee.isNullOrEmpty()) throw MeetingException("Attendee must have a name")
    }

    companion object {
        // by marking @JvmField & @JvmStatic, we can make it easy to use in java
        @JvmField
        val APP_VERION = 1

        @JvmStatic
        fun getAppVersion(): Int {
            return APP_VERION
        }
    }
}

class MeetingException(message: String): Exception(message) {

}

 

Create a Java class to use Kotlin:

package com.rsk.java;

import com.rsk.kotlin.Meeting;
import com.rsk.kotlin.MeetingException;

public class Program {
    public static void main(String[] args) {
        Meeting board = new Meeting("Board Meeting");
        board.setLocation("London");
        System.out.println(board.getLocation());

        board.description = "React meeting";
        System.out.println(board.description);

        System.out.println(Meeting.APP_VERION);
        System.out.println(Meeting.getAppVersion());

        try {
            board.addAttendee("");
        } catch(MeetingException me) {
            me.printStackTrace();
        }

    }
}