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IntToDoubleFunction is a functional interface from java.util.function package. This functional interface accepts an int-valued argument and produces a double-valued result. IntToDoubleFunction can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: applyAsDouble().Syntax@FunctionalInterface interface IntToDoubleFunction { double applyAsDouble(int value); }Example of Lambda Expressionimport java.util.function.IntToDoubleFunction;; public class IntToDoubleLambdaTest { public static void main(String[] args) { IntToDoubleFunction getDouble = intVal -> { // lambda expression double doubleVal = intVal; return doubleVal; }; int input ... Read More
DoubleToIntFunction is a functional interface defined in java.util.function package introduced in Java 8 version. This functional interface accepts a double-valued argument and produces an int-valued result. DoubleToIntFunction interface can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: applyAsInt().Syntax@FunctionalInterface interface DoubleToIntFunction { int applyAsInt(double value) }Exampleimport java.util.function.DoubleToIntFunction; public class DoubleToIntFunctionTest { public static void main(String args[]) { DoubleToIntFunction test = doubleVal -> { // lambda expression int intVal = (int) doubleVal; return intVal; }; ... Read More
DoubleToLongFunction is a built-in functional interface from java.util.function package introduced in Java 8. This functional interface accepts a double-valued parameter and produces a long-valued result. DoubleToLongFunction interface can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: applyAsLong().Syntax@FunctionalInterface public interface DoubleToLongFunction { long applyAsLong(double value) }Exampleimport java.util.function.DoubleToLongFunction; public class DoubleToLongFunctionTest { public static void main(String args[]) { double dbl = 30.1212; DoubleToLongFunction castToLong = (dblValue) -> (long) dblValue; // lambda expression System.out.println(castToLong.applyAsLong(dbl)); dbl = 77.9212; DoubleToLongFunction roundToLong = Math::round; ... Read More
A lambda expression is a function that expects and accepts input parameters and produces output results. It is an instance of a functional interface and also known as a single abstract method interface (SAM interface) like Runnable, Comparator, Callable and etc. We can declare a variable as a final string[] array and able to access that array index within a lambda expression.Exampleimport java.util.*; public class LambdaTest { public static void main(String args[]) { final String[] country = {null}; List cities = new ArrayList(); cities.add("Hyderabad"); cities.add("Ireland"); cities.add("Texas"); ... Read More
ToLongBiFunction is a in-built functional interface from java.util.function package. This functional interface accepts two reference type parameters as input and produces a long-valued result. ToLongBiFunction interface can be used as an assignment target for a lambda expression or method reference and contains only one abstract method: applyAsLong().Syntax@FunctionalInterface interface ToLongBiFunction { long applyAsLong(T t, U u); }Exampleimport java.util.*; import java.util.function.ToLongBiFunction; public class ToLongBiFunctionTest { public static void main(String[] args) { ToLongBiFunction getMobileNum = (map, value) -> { // lambda if(map != null && !map.isEmpty()) { if(map.containsKey(value)) { ... Read More
ToLongFunction is a functional interface defined in java.util.function package. This functional interface accepts a reference type as input and produces a long-valued result. ToLongFunction interface can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: applyAsLong().Syntax@FunctionalInterface interface ToLongFunction { long applyAsLong(T value); }Exampleimport java.util.*; import java.util.function.ToLongFunction; public class ToLongFunctionTest { public static void main(String args[]) { List list = new ArrayList(); list.add("11"); list.add("22"); list.add("33"); list.add("44"); list.add("55"); ToLongFunction function = (String item) -> Long.valueOf(item); // ... Read More
ToIntBiFunction is a built-in functional interface from java.util.function package. This interface accepts two parameters as input and produces an int-valued result. ToIntBiFunction interface can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: applyAsInt() and doesn't contain any default or static methods.Syntax@FunctionalInterface interface ToIntBiFunction { int applyAsInt(T t, U u); }Exampleimport java.util.function.ToIntBiFunction; public class ToIntBiFunctionTest { public static void main(String args[]) { ToIntBiFunction test = (t, u) -> t * u; System.out.println("The multiplication of t and u is: " + test.applyAsInt(10, 7)); System.out.println("The multiplication of t and u is: " ... Read More
ToDoubleBiFunction is a functional interface defined in java.util.function package. This functional interface accepts two parameters as input and produces a double-valued result. ToDoubleBiFunction interface can be used as an assignment target for a lambda expression or method reference. This interface contains only one abstract method: applyAsDouble() and doesn't contain any default or static methods.Syntax@FunctionalInterface interface ToDoubleBiFunction { double applyAsDouble(T t, U u); }Exampleimport java.util.function.ToDoubleBiFunction; public class ToDoubleBiFunctionTest { public static void main(String args[]) { ToDoubleBiFunction test = (t, u) -> t / u; // lambda expression System.out.println("The division of t and u is: " + test.applyAsDouble(50, ... Read More
A Map interface implements the Collection interface that provides the functionality of the map data structure. A Map doesn't contain any duplicate keys and each key is associated with a single value. We can able to access and modify values using the keys associated with them.In the below two examples, we can able to sort a Map by both key and value with the help of lambda expression.Example for sorting of Map using Keyimport java.util.*; import java.util.stream.*; public class MapSortUsingKeyTest { public static void main(String args[]) { // Sort a Map by their key Map map = new HashMap(); ... Read More
LongUnaryOperator is a functional interface from java.util.function package. This functional interface accepts a single long-valued operand and produces a long-valued result. LongUnaryOperator interface can be used as an assignment target for lambda expression and method reference. It contains one abstract method: applyAsLong(), one static method: identity() and two default methods: andThen() and compose().Syntax@FunctionalInterface public interface LongUnaryOperator long applyAsLong(long operand); }Exampleimport java.util.function.LongUnaryOperator; public class LongUnaryOperatorTest { public static void main(String args[]) { LongUnaryOperator getSquare = longValue -> { // lambda long result = longValue * longValue; System.out.println("Getting square: " + result); ... Read More