- Java
System.out.print("Dhimant Desai"); System.out.println("Dhimant Desai");- Kotlin
print("Dhimant Desai") println("Dhimant Desai")- Java
String name = "Dhimant Desai"; final String name = "Dhimant Desai";- Kotlin
var name = "Dhimant Desai"- Java
String otherName; otherName = null;- Kotlin
var otherName : String? otherName = null- Java
if (text != null) { int length = text.length(); }- Kotlin
text?.let { val length = text.length } // or simple val length = text?.length- Java
String firstName = "Dhimant"; String lastName = "Desai"; String message = "My name is: " + firstName + " " + lastName;- Kotlin
val firstName = "Dhimant" val lastName = "Desai" val message = "My name is: $firstName $lastName"- Java
String text = "First Line\n" + "Second Line\n" + "Third Line";- Kotlin
val text = """ |First Line |Second Line |Third Line """.trimMargin()- Java
String text = x > 5 ? "x > 5" : "x <= 5";- Kotlin
val text = if (x > 5) "x > 5" else "x <= 5"- java
final int andResult = a & b; final int orResult = a | b; final int xorResult = a ^ b; final int rightShift = a >> 2; final int leftShift = a << 2;- Kotlin
val andResult = a and b val orResult = a or b val xorResult = a xor b val rightShift = a shr 2 val leftShift = a shl 2- Java
if (object instanceof Car) { } Car car = (Car) object;- Kotlin
if (object is Car) { } var car = object as Car- Java
if (object instanceof Car) { Car car = (Car) object; }- Kotlin
if (object is Car) { var car = object // smart casting }- Java
if (score >= 0 && score <= 300) { }- Kotlin
if (score in 0..300) { }- Java
int score = // some score; String grade; switch (score) { case 10: case 9: grade = "Excellent"; break; case 8: case 7: case 6: grade = "Good"; break; case 5: case 4: grade = "Ok"; break; case 3: case 2: case 1: grade = "Fail"; break; default: grade = "Fail"; }- Kotlin
var score = // some score var grade = when (score) { 9, 10 -> "Excellent" in 6..8 -> "Good" 4, 5 -> "Ok" in 1..3 -> "Fail" else -> "Fail" }- Java
for (int i = 1; i <= 10 ; i++) { } for (int i = 1; i < 10 ; i++) { } for (int i = 10; i >= 0 ; i--) { } for (int i = 1; i <= 10 ; i+=2) { } for (int i = 10; i >= 0 ; i-=2) { } for (String item : collection) { } for (Map.Entry<String, String> entry: map.entrySet()) { }- Kotlin
for (i in 1..10) { } for (i in 1 until 10) { } for (i in 10 downTo 0) { } for (i in 1..10 step 2) { } for (i in 10 downTo 1 step 2) { } for (item in collection) { } for ((key, value) in map) { }- Java
final List<Integer> listOfNumber = Arrays.asList(1, 2, 3, 4); final Map<Integer, String> keyValue = new HashMap<Integer, String>(); map.put(1, "Dhimant"); map.put(2, "Desai"); map.put(3, "Dhims"); // Java 9 final List<Integer> listOfNumber = List.of(1, 2, 3, 4); final Map<Integer, String> keyValue = Map.of(1, "Dhimant", 2, "Desai", 3, "Dhims");- Kotlin
val listOfNumber = listOf(1, 2, 3, 4) val keyValue = mapOf(1 to "Dhimant", 2 to "Desai", 3 to "Dhims")- Java
// Java 7 and below for (Car car : cars) { System.out.println(car.speed); } // Java 8+ cars.forEach(car -> System.out.println(car.speed)); // Java 7 and below for (Car car : cars) { if (car.speed > 100) { System.out.println(car.speed); } } // Java 8+ cars.stream().filter(car -> car.speed > 100).forEach(car -> System.out.println(car.speed));- Kotlin
cars.forEach { println(it.speed) } cars.filter { it.speed > 100 } .forEach { println(it.speed)}- Java
void doSomething() { // logic here } void doSomething(int... numbers) { // logic here }- Kotlin
fun doSomething() { // logic here } fun doSomething(vararg numbers: Int) { // logic here }- Java
int getScore() { // logic here return score; }- Kotlin
fun getScore(): Int { // logic here return score } // as a single-expression function fun getScore(): Int = score- Java
int getScore(int value) { // logic here return 2 * value; }- Kotlin
fun getScore(value: Int): Int { // logic here return 2 * value } // as a single-expression function fun getScore(value: Int): Int = 2 * value- Java
public class Utils { private Utils() { // This utility class is not publicly instantiable } public static int getScore(int value) { return 2 * value; } }- Kotlin
class Utils private constructor() { companion object { fun getScore(value: Int): Int { return 2 * value } } } // other way is also there object Utils { fun getScore(value: Int): Int { return 2 * value } }- Java
public class Developer { private String name; private int age; public Developer(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Developer developer = (Developer) o; if (age != developer.age) return false; return name != null ? name.equals(developer.name) : developer.name == null; } @Override public int hashCode() { int result = name != null ? name.hashCode() : 0; result = 31 * result + age; return result; } @Override public String toString() { return "Developer{" + "name='" + name + '\'' + ", age=" + age + '}'; } }- Kotlin
data class Developer(val name: String, val age: Int) - Java
public class Utils { private Utils() { // This utility class is not publicly instantiable } public static int triple(int value) { return 3 * value; } } int result = Utils.triple(3);- Kotlin
fun Int.triple(): Int { return this * 3 } var result = 3.triple()