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Java Articles
Page 281 of 450
How to implement LongPredicate using lambda and method reference in Java?
LongPredicate is a functional interface defined in java.util.function package. This interface can be used mainly for evaluating an input of type long and returns an output of type boolean. LongPredicate can be used as an assignment target for a lambda expression or method reference. It contains one abstract method: test() and three default methods: and(), negate() and or().Syntax@FunctionalInterface interface LongPredicate { boolean test(long value); }Example of Lambda Expressionimport java.util.function.LongPredicate; public class LongPredicateLambdaTest { public static void main(String args[]) { LongPredicate longPredicate = (long input) -> { ...
Read MoreHow to implement IntBinaryOperator using lambda expression in Java?
IntBinaryOperator is a functional interface in Java 8 from java.util.function package. This interface expects two parameters of type int as input and produces an int type result. IntBinaryOperator can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: applyAsInt().Syntax@FunctionalInterface public interface IntBinaryOperator { int applyAsInt(int left, int right) }Exampleimport java.util.function.*; public class IntBinaryOperatorTest { public static void main(String[] args) { IntBinaryOperator test1 = (a, b) -> a + b; // lambda expression System.out.println("Addition of ...
Read MoreHow to implement Function interface with lambda expression in Java?
Function interface is a functional interface from java.util.function package. This interface expects one argument as input and produces a result. Function interface can be used as an assignment target for a lambda expression or method reference. It contains one abstract method: apply(), two default methods: andThen() and compose() and one static method: identity().Syntax@FunctionalInterface public interface Function { R apply(T t); }Exampleimport java.util.function.Function; public class FunctionTest { public static void main(String[] args) { Function f1 = i -> i*4; // lambda System.out.println(f1.apply(3)); ...
Read MoreHow to implement DoubleSupplier using lambda and method reference in Java?
DoubleSupplier interface is a built-in functional interface defined in java.util.function package. This functional interface doesn’t expect any input but produces a double-valued output. DoubleSupplier interface can be used as an assignment target for lambda expression and method reference. This interface contains only one abstract method: getAsDouble().Syntax@FunctionalInterface public interface DoubleSupplier { double getAsDouble(); }Example of Lambda Expressionimport java.util.concurrent.ThreadLocalRandom; import java.util.function.DoubleSupplier; public class DoubleSupplierLambdaTest { public static void main(String args[]) { DoubleSupplier getRandomDouble = () -> { // lambda expression ...
Read MoreHow to create our own/custom functional interface in Java?
The functional interface is a simple interface with only one abstract method. A lambda expression can be used through a functional interface in Java 8. We can declare our own/custom functional interface by defining the Single Abstract Method (SAM) in an interface.Syntaxinterface CustomInterface { // abtstact method }Example@FunctionalInterface interface CustomFunctionalInterface { void display(); } public class FunctionInterfaceLambdaTest { public static void main(String args[]) { // Using Anonymous inner class CustomFunctionalInterface test1 = new CustomFunctionalInterface() { ...
Read MoreHow to implement ObjLongConsumer interface using lambda expression in Java?
ObjLongConsumer is a functional interface from java.util.function package. This interface accepts an object-valued and long-valued argument as input but doesn't produce any output. ObjLongConsumer can be used as an assignment target for lambda expression and method reference and contains only one abstract method: accept().Syntax@FunctionalInterface public interface ObjLongConsumer { void accept(T t, long value) }Exampleimport java.util.function.ObjLongConsumer; public class ObjLongConsumerTest { public static void main(String[] args) { ObjLongConsumer olc = (employee, number) -> { // lambda expression if(employee != null) { System.out.println("Employee Name: " + employee.getEmpName()); ...
Read MoreHow to implement LongFunction using lambda and method reference in Java?
LongFunction is an in-built functional interface defined in java.util.function package. This functional interface expects a long-valued parameter as input and produces a result. LongFunction interface can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: apply().Syntax@FunctionalInterface public interface LongFunction { R apply(long value) }Exampleimport java.util.function.LongFunction; public class LongFunctionTest { public static void main(String[] args) { LongFunction function1 = (long i) -> { // lambda expression return i + i; ...
Read MoreHow to implement LongBinaryOperator using lambda and method reference in Java?
LongBinaryOperator is a part of the functional interface from java.util.function package. This functional interface expects two parameters of type long as the input and produces a long type result. LongBinaryOperator 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 LongBinaryOperator { long applyAsLong(long left, long right) }Example of Lambda Expressionimport java.util.function.LongBinaryOperator; public class LongBinaryOperatorTest1 { public static void main(String[] args) { LongBinaryOperator multiply = (a, b) -> { // lambda expression return a*b; }; long a = ...
Read MoreHow to implement IntConsumer using lambda and method reference in Java?
IntConsumer interface is a functional interface from java.util.function package in Java 8. This interface accepts a single int-valued argument as input but doesn't produce any output. Since it is a functional interface, it can be used as an assignment target for a lambda expression or method reference. It contains one abstract method: accept() and one default method: andThen().Syntax@FunctionalInterface public interface IntConsumer { void accept(int value); }Example of Lambda Expressionimport java.util.function.IntConsumer; public class IntConsumerTest1 { public static void main(String[] args) { IntConsumer displayNextInt = i -> System.out.println("Next Int ...
Read MorePreconditions - Java
Precondition to check if the list passed as parameter is empty or not. Let us see an example −Examplepublic void my_fun(List myList){ if (myList == null){ throw new IllegalArgumentException("List is null"); } if (myList.isEmpty()){ throw new IllegalArgumentException("List is empty"); } my_fun(myList); }A void function named ‘my_fun’ is defined that takes a list of objects as its parameters. If the list is null, it prints the relevant message. If the list has no elements in it, a specific message is displayed. The function is called by passing the list as ...
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