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What kind of variables/methods defined in an interface in Java 9?
Since Java 9, we able to add private methods and private static methods in an interface. The advantage of using private methods in an interface is to reduce code duplication among default and static methods. For instance, if two or more default methods needed to share some code, a private method can be created for the same and called from each of the default methods.
In Java 9, the following variables/methods have defined in an interface.
- Constant
- Abstract method
- Default method
- Static method
- Private method
- Private Static method
Example
import java.util.*;
import java.util.stream.*;
interface InterfaceTest {
static void printEvenNumbers() {
getDataStream().filter(i -> i%2==0).forEach(System.out::println);
}
static void printLOddNumbers() {
getDataStream().filter(i -> i%2!=0).forEach(System.out::println);
}
private static Stream<Integer> getDataStream() { // private static method
List<Integer> list = Arrays.asList(10, 13, 5, 15, 12, 20, 11, 25, 16);
return list.stream();
}
}
public class InterfacePrivateMethodTest implements InterfaceTest {
public static void main(String args[]) {
System.out.println("The even numbers: ");
InterfaceTest.printEvenNumbers();
System.out.println("The odd numbers: ");
InterfaceTest.printLOddNumbers();
}
}Output
The even numbers: 10 12 20 16 The odd numbers: 13 5 15 11 25
Updated on: 24-Feb-2020
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