我有一个Person类，它有几个变量。 City类具有Person对象列表作为其唯一变量。类State将城市对象列表作为唯一变量。
在测试类中，我创建了一个包含City对象的arraylist。如何对列表中的City对象进行排序？即，如何对包含一种对象的arraylist进行排序，其中每个对象中都有另一个列表。
人类
public class Person {
private String name;
private Integer age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public static Comparator<Person> personComparator = new Comparator<Person>() {
@Override
public int compare(Person o1, Person o2) {
int returnResult = o1.getName().compareTo(o2.getName());
if (returnResult == 0) {
return o1.getAge().compareTo(o2.getAge());
}
return returnResult;
}
};
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((age == null) ? 0 : age.hashCode());
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof Person))
return false;
Person other = (Person) obj;
if (age == null) {
if (other.age != null)
return false;
} else if (!age.equals(other.age))
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
}
城市课程：
public class City {
private List<Person> personList;
public List<Person> getPersonList() {
if (personList == null) {
personList = new ArrayList<Person>();
}
return personList;
}
public void setPersonList(List<Person> personList) {
this.personList = personList;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result
+ ((personList == null) ? 0 : personList.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof City))
return false;
City other = (City) obj;
if (personList == null) {
if (other.personList != null)
return false;
} else if (!personList.equals(other.personList))
return false;
return true;
}
}
州级：
public class State {
private List<City> cityList;
public List<City> getCityList() {
if (cityList == null) {
cityList = new ArrayList<City>();
}
return cityList;
}
public void setCityList(List<City> cityList) {
this.cityList = cityList;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result
+ ((cityList == null) ? 0 : cityList.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof State))
return false;
State other = (State) obj;
if (cityList == null) {
if (other.cityList != null)
return false;
} else if (!cityList.equals(other.cityList))
return false;
return true;
}
}
public class TestClass {
public static void main(String[] args) {
Person p1 = new Person();
p1.setName("John");
p1.setAge(40);
Person p2 = new Person();
p2.setName("Antony");
p2.setAge(50);
Person p3 = new Person();
p3.setName("Bob");
p3.setAge(24);
Person p4 = new Person();
p4.setName("Mark");
p4.setAge(35);
City city1 = new City();
city1.getPersonList().add(p1);
city1.getPersonList().add(p2);
City city2 = new City();
city2.getPersonList().add(p3);
city2.getPersonList().add(p4);
State state1 = new State();
state1.getCityList().add(city1);
state1.getCityList().add(city2);
//How to sort the citylist in the state object?
}
}