球员类：

public class Players {

private static int count = 0; //创建一个对象，count会加1

private static int num = 11; //最多创建11个对象

private String name;

private int age;

private String sex;

private Players() {

count++;

}

private Players(String name, int age, String sex) {

this.name = name;

this.age = age;

this.sex = sex;

count++;

}

public static Players createNewPlayer() {

//count

if (count < num) {

return new Players();

} else {

return null;

}

}

public static Players createNewPlayer(String name, int age, String sex) {

//count

if(count < num) {

return new Players(name, age, sex);

} else {

return null;

}

}

public static int getCount() {

return count;

}

public static void setCount(int count) {

Players.count = count;

}

public static int getNum() {

return num;

}

public static void setNum(int num) {

Players.num = num;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

public String getSex() {

return sex;

}

public void setSex(String sex) {

this.sex = sex;

}

}

测试类：

public class Test {

public static void main(String[] args) {

while (true) {

Players player = Players.createNewPlayer();

if(player == null) {

System.out.println("对不起，已经创建了" + Players.getNum() + "个球员对象");

break;

} else {

System.out.println("创建了第" + Players.getCount() + "个球员对象！");

}

}

}

}

运行结果：