Coexistence of Kotlin and Java, calling kotlin code in -Java

Call of kotlin data class

kotlin Code:

package com.tianfu.kotlin

/**
 * age Member annotations cannot have get and set methods. They can only assign values directly and cannot declare private
 */
data class Person(var name:String,@JvmField var age:Int)

java code

import com.tianfu.kotlin.Person;

public class PersonMain {
    public static void main(String[] args) {
        Person person=new Person("Andy",27);
        System.out.println(person.getName()+" is "+person.age);//There are no get and set methods for age here
        person.setName("Boby");
        person.age=37;
        System.out.println(person.getName()+" is "+person.age);
//        person.setName(null); you can't leave it empty here. An error will be reported when running
    }
}

result:

Call of object simple profit mode class in Kotlin

kotlin Code:

package com.tianfu.kotlin

object Singleton {
    fun syhello(){
        println("The Ming moon in Qin Dynasty")
    }
}

java code

import com.tianfu.kotlin.Singleton;

public class AccessToObject {
    public static void main(String[] args) {
        Singleton.INSTANCE.syhello();
    }
}

Calling file class in Kotlin

kotlin code

package com.tianfu.kotlin

/**
 * kotlinFile The File will be compiled into the corresponding class
 */
fun printHello(){
    println("Only by crossing the sea can we show the true qualities of a hero")
}

fun main(args: Array<String>) {
    printHello()
}

Calling Java code

import com.tianfu.kotlin.PackageKt;

public class CallPackageMethod {
    public static void main(String[] args) {
        PackageKt.printHello();//Compile the kotlinfile of package into class, then adjust the method.
    }
}

Call of jvm annotation, flexible transfer of parameters

kotlin annotation code

package com.tianfu.kotlin

class OverLoads {
    @JvmOverloads//If you add this annotation, the method parameters will have default values. Otherwise, all three parameters will be passed in java
    fun overloaded(a:Int,b:Int=0,c:Int=1){
        println("$a,$b,$c")
    }
}

Java call code

import com.tianfu.kotlin.OverLoads;

public class AccessToOverLoads {
    public static void main(String[] args) {
        OverLoads overLoads=new OverLoads();
        overLoads.overloaded(10,11,12);//Methods with three parameters
        overLoads.overloaded(13);//b. C use the default value
        overLoads.overloaded(12,13);//c use the default value
    }
}

String string null call

kotlin code

package com.tianfu.kotlin

fun String.notEmpty():Boolean{//There are no parameters
    return this !=""
}

Java code to achieve null, direct transfer parameters

import com.tianfu.kotlin.ExtensionMethodKt;

public class CallExtensionMethod {
    public static void main(String[] args) {
        System.out.println(ExtensionMethodKt.notEmpty("Blue sky and misty rain"));
    }
//    Results: true
}

Tags: Java jvm

Posted on Wed, 08 Jul 2020 12:02:49 -0400 by gareh