Interface in Java 8

1.Default Methods in Interfaces
Java 8 introduced a new keyword default. Now you’re allowed to write a default implementation of a method in the interface. Such a method won’t be considered abstract anymore, and you won’t be forced to implement it in your class.

2.Static Methods in Interfaces
Starting from Java 8, interfaces are also allowed to include static methods, which are not specific to any instance and can be used only internally by other methods of the interface.

public interface testInter{
    public void test1(int i);
    public default void test2(int i){
        System.out.println("Default Method!");

        if(isJUNE()){System.out.println("There is a Static Method.");} 
    };

   //Static Method,which are not specific to any instance
   //and can be used only internally by other methods of the interface.
    static boolean isJUNE(){
        Month month = LocalDate.now().getMonth();
        if (month == Month.JUNE){
            return true;
        } else{
            return false;
        }
    } 
}

3.Java 8 introduced a special way of implementing functional interfaces using lambda expressions

public interface test1ForLambdaInter {
    public String test(String s);
}

public class MainTest{
  public static void main(String[] args) {

   test1ForLambdaInter  t= (arg) -> {
         return  "The arg is " + args;
     }; 

    String name="demo";    
    t(name); 
  }
}

System.out.println("JVM has a default character set:"
+Charset.defaultCharset());
The Java classes FileReader and FileWriter from the package java.io,
they work only with default character encoding. 

SortedMap map = Charset.availableCharsets();
  String[] charSets = new String[map.size()];
  int i = 0;
  for (Iterator iter = map.keySet().iterator(); iter.hasNext(); i++) {
    charSets[i] = (String)iter.next();
  } 

https://www.infoq.com/articles/Java9-New-HTTP-2-and-REPL

https://adopt-openjdk.ci.cloudbees.com/view/OpenJDK/job/langtools-1.9-linux-x86_64-kulla-dev/

http://hg.openjdk.java.net/kulla/dev