List<Contact> contacts = new ArrayList<>();
contactList.forEach(new Consumer<String>() {
 @Override
 public void accept(String s) {
  Contact contact = new Contact();
  contact.setName(s);
  contacts.add(contact);
 }
});

List<Contact> validContacts = new ArrayList<>();
contacts.forEach(new Consumer<Contact>() {
 @Override
 public void accept(Contact c) {
  if (c.call())
   validContacts.add(c);
 }
});
System.out.println(validContacts.size());

public interface Stream<T> extends BaseStream<T, Stream<T>> {}

Stream<Contact> contactStream = contactList.stream().map(s -> new Contact().setName(s));

Stream<String> stringStream = contactList.stream();
Stream<Contact> contactStream1 = stringStream.map(s -> new Contact().setName(s));

long validContactCounter = 
 contactList.stream()
  .map(s -> new Contact().setName(s))
  .filter(c -> c.call())
  .count();

import java.util.Random;
public class Contact {
 private String name;
 private long number;
 private Random random;
 public Contact() {
  random = new Random();
 }
 public String getName() {
  return name;
 }
 public Contact setName(String name) {
  this.name = name;
  return this;
 }
 public long getNumber() {
  return number;
 }
 public Contact setNumber(long number) {
  this.number = number;
  return this;
 }
 public boolean call() {
  return random.nextBoolean();
 }
}
（运行用）

List<Contact> contacts = new ArrayList<>();
contactList.forEach(new Consumer<String>() {
 @Override
 public void accept(String s) {
  Contact contact = new Contact();
  contact.setName(s);
  contacts.add(contact);
 }
});
List<Contact> validContacts = new ArrayList<>();
contacts.forEach(new Consumer<Contact>() {
 @Override
 public void accept(Contact contact) {
  if (contact.call())
   validContacts.add(contact);
 }
});
System.out.println(validContacts.size());
//--- Stream is coming ---//
Stream<Contact> contactStream = contactList.stream().map(s -> new Contact().setName(s));
//--- Break this code ---//
Stream<String> stringStream = contactList.stream();
Stream<Contact> contactStream1 = stringStream.map(s -> new Contact().setName(s));
//--- All in one ---//
long validContactCounter = 
 contactList.stream()
  .map(s -> new Contact().setName(s))
  .filter(c -> c.call())
  .count();
System.out.println(validContactCounter);