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How to implement LongToDoubleFunction using lambda and method reference in Java?
LongToDoubleFunction is a built-in functional interface and part of java.util.function package. This functional interface accepts a long-valued parameter as input and produces a double-valued result. LongToDoubleFunction can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: applyAsDouble().
Syntax
@FunctionalInterface
interface LongToDoubleFunction {
double applyAsDouble(long value);
}Example of Lambda Example
import java.util.function.LongToDoubleFunction;
public class LongToDoubleLambdaTest {
public static void main(String args[]) {
LongToDoubleFunction getDouble = longVal -> { // lambda expression
double doubleVal = longVal;
return doubleVal;
};
long input = 565758L;
System.out.println("The input is: " + input);
double result = getDouble.applyAsDouble(input);
System.out.println("The result is: " + result);
}
}Output
The input is: 565758 The result is: 565758.0
Example of Method Reference
import java.util.function.LongToDoubleFunction;
public class LongToDoubleMethodRefTest {
public static void main(String args[]) {
LongToDoubleFunction result = LongToDoubleMethodRefTest::convertLongToDouble; // method reference
System.out.println(result.applyAsDouble(75));
System.out.println(result.applyAsDouble(60));
}
static Double convertLongToDouble(long value) {
return (double)value / 5;
}
}Output
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Updated on: 15-Jul-2020
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