为什么输出大儿子和二儿子的名字一样。

Question

public class FamilyPerson {static String surname;String name;public static void setSurname(String s){surname = s;}public void setName(String s){name = s;}} public class MainClass {public static void main(String args[]){FamilyPerson.surname="李";FamilyPerson father,sonOne,sonTwo;father = new FamilyPerson();sonOne = new FamilyPerson();sonTwo = new FamilyPerson();father.setName("向阳");sonOne.setName("抗日");sonTwo.setName("抗战");System.out.println("父亲："+father.surname+father.name);System.out.println("大儿子："+sonOne.surname+sonOne.name);System.out.println("二儿子："+sonTwo.surname+sonOne.name);father.surname="张";System.out.println("父亲："+father.surname+father.name);System.out.println("大儿子："+sonOne.surname+sonOne.name);System.out.println("二儿子："+sonTwo.surname+sonOne.name);}}