STATIC METHODS
Java 8 allows static methods in interfaces.
/**
* Static methods are allowed in interfaces (Java 8)
* It's always better to put related methods in the same place
*/
package com.minte9.lambdas.static_methods;
import java.util.function.BinaryOperator;
import java.util.stream.Stream;
import static org.junit.Assert.assertEquals;
public class StaticMethod {
public static void main(String[] args) {
int a = MyStream.of(1, 2, 3)
.reduce(0, (acc, x) -> acc + x) // addition
;
int b = MyStream.of(1, 2, 3)
.reduce(0, (acc, x) -> acc - x) // substraction
;
assertEquals(a, 6);
assertEquals(b, -6);
System.out.println("Tests passed");
}
}
abstract interface MyStream<T> extends Stream<T> {
@SafeVarargs
@SuppressWarnings("varargs")
static <T> Stream<T> of(T... values) { // Look Here
return Stream.of(values);
}
abstract T reduce(T arg0, BinaryOperator<T> arg1);
}
Method Reference
The syntax when lambdas call methods on its parameter is named method reference.
/**
* Method reference
*
* Use a lambdas that call methods on its parameter
* Standard form of method reference is ClassName::methodName
* The code is not only more shorter, also a lot easier to read
*/
package com.minte9.lambdas.static_methods;
import java.util.Arrays;
import java.util.List;
public class MethodReference {
public static void main(String[] args) {
List<String> myList = Arrays.asList("a", "b", "c");
myList.stream()
.map(x -> x + x)
.map(String::toUpperCase)
.forEach(System.out::println); // AA BB CC
}
}
Last update: 595 days ago
