SampleConsumer.java

interface Consumer<T> {
  void accept(T value);
}


// create Consumer by defining a class explicitly
class HelloWorldPrinter implements Consumer<String> {
  public void accept(String name) {
    System.out.println("Hello World! " + name); 
  }
}
HelloWorldPrinter printer1 = new HelloWorldPrinter();
printer1.accept("SJ");  // prints out "Hello World! SJ"

// method reference from existing ones
Consumer<String> reference = printer1::accept;
reference.accept("SJ");  // also prints out "Hello World! SJ"


// create Consumer with anonymous class
Consumer<String> printer2 = new Consumer<>() {
  @Override
  public void accept(String name) {
    System.out.println("Hello World! " + name);
  }
};
printer2.accept("SJ");  // also prints out "Hello World! SJ"


// create Consumer with lambda expression
Consumer<String> printer3 = (name) -> {
  System.out.println("Hello World! " + name);
};
printer3.accept("SJ");  // also prints out "Hello World! SJ"