用默认方法创建一个接口，任何实现该接口的类都可以使用该方法。
import java.util.List; interface TeamType { /*来 自 NowJava.com - 时代Java*/ List<Player> getPlayers(); void setPlayers(List<Player> players); void setName(String name); void setCity(String city); String getFullName(); /* 来自 时 代 J a v a 公 众 号*/ default void listPlayers() { getPlayers().stream().forEach((player) -> { System.out.println(player.getFirstName() + " " + player.getLastName()); }); } } class Player { private String firstName; private String lastName; private String position; private int status = -1; public Player(){ } public Player(String position, int status){ this.position = position; this.status = status; } public String playerString(){ return getFirstName() + " " + getLastName() + " - " + getPosition(); } /** * @return the firstName */ public String getFirstName() { return firstName; } /** * @param firstName the firstName to set */ public void setFirstName(String firstName) { this.firstName = firstName; } /** * @return the lastName */ public String getLastName() { return lastName; } /** * @param lastName the lastName to set */ public void setLastName(String lastName) { this.lastName = lastName; } /** * @return the position */ public String getPosition() { return position; } /** * @param position the position to set */ public void setPosition(String position) {