在Java中使用equals方法查找相等对象

我有一个对象列表，该对象具有名称，地址第1行，地址第2行，城市，listOfPeopleMatched属性。我正在通过覆盖equals和hashcode方法找到基于地址line1，地址line2和城市（而非名称）的相等性。现在，我想获取对象匹配的人员的姓名，并将其存储在listOfPeopleMatched中。例如：[[“ Val”，“ Ashish”]，[“ Steve”，“ Alex”]]。仅用equals方法怎么做到？

public class Person {

private String name;
private String addressLine1;
private String addressLine2;
private String city;
private List<List<String>> listOfPeopleMatched = 
                             new ArrayList<List<String>>();

public String getName() {
    return name;
}

public List<List<String>> getListOfPeopleMatched() {
    return listOfPeopleMatched;
}

public void setListOfPeopleMatched(List<List<String>> listOfPeopleMatched) {
    this.listOfPeopleMatched = listOfPeopleMatched;
}

public void setName(String name) {
    this.name = name;
}

public String getAddressLine1() {
    return addressLine1;
}

public void setAddressLine1(String addressLine1) {
    this.addressLine1 = addressLine1;
}

public String getAddressLine2() {
    return addressLine2;
}

public void setAddressLine2(String addressLine2) {
    this.addressLine2 = addressLine2;
}

public String getCity() {
    return city;
}

public void setCity(String city) {
    this.city = city;
}

public Person(String name, String addressLine1, 
        String addressLine2, String city) {
    super();
    this.name = name;
    this.addressLine1 = addressLine1;
    this.addressLine2 = addressLine2;
    this.city = city;
}

@Override
public String toString() {
    return "Person [name=" + name + 
                    ", addressLine1=" + 
                    addressLine1 + ", addressLine2=" + 
                    addressLine2 + ", city="
            + city + "]";
}

@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((addressLine1 == null) ? 
            0 : addressLine1.hashCode());
    result = prime * result + ((addressLine2 == null) ? 
            0 : addressLine2.hashCode());
    result = prime * result + ((city == null) ? 
            0 : city.hashCode());
    return result;
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Person other = (Person) obj;
    if (addressLine1 == null) {
        if (other.addressLine1 != null)
            return false;
    } else if (!addressLine1.equals(other.addressLine1))
        return false;
    if (addressLine2 == null) {
        if (other.addressLine2 != null)
            return false;
    } else if (!addressLine2.equals(other.addressLine2))
        return false;
    if (city == null) {
        if (other.city != null)
            return false;
    } else if (!city.equals(other.city))
        return false;
    return true;
}

} Person person1 = new Person("Val", "ABC", "Shivaji Nagar", "Pune"); Person person2 = new Person("Ashish", "ABC", "Shivaji Nagar", "Pune"); Person person3 = new Person("Steve", "MNO", "Shivaji Nagar", "Pune"); Person person4 = new Person("Alex", "MNO", "Shivaji Nagar", "Pune");

Set uniquePeople = new HashSet<>(); uniquePeople.add(person1); uniquePeople.add(person2); uniquePeople.add(person3); uniquePeople.add(person4);

System.out.println(uniquePeople);

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小六码奴 2019-10-16 18:14:50 10683 0

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苍霞学子

下一站是幸福

public static void main(String[] args) {


    // what we're searching for
    Address address = new Address("123 N 3rd st", "east ohg", "this-city");

    // init
    List<Person> persons = new ArrayList<>();
    persons.add(new Person("Jim", "123 N 56 st", "east ohg", "this-city"));
    persons.add(new Person("Kyle", "145 N 67th st", "east ohg", "this-city"));
    persons.add(new Person("Sam", "12 beach av", "east ohg", "this-city"));
    persons.add(new Person("Tracy", "123 N 3rd st", "east ohg", "this-city"));
    persons.add(new Person("Ashley", "123 N 3rd st", "east ohg", "this-city"));


    // search
    List<Person> people = persons.stream().filter(person -> person.address.equals(address)).collect(Collectors.toList());

    people.forEach(System.out::println);


}

String name;
Address address;

public Person(String name,
              String addressLine1,
              String addressLine2,
              String city) {
    this.name = name;
    this.address = new Address(addressLine1,
                               addressLine2,
                               city);
}

private static final class Address {
    String addressLine1;
    String addressLine2;
    String city;


    public Address(String addressLine1, String addressLine2, String city) {
        this.addressLine1 = addressLine1;
        this.addressLine2 = addressLine2;
        this.city = city;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Address address = (Address) o;
        return Objects.equals(addressLine1, address.addressLine1) &&
               Objects.equals(addressLine2, address.addressLine2) &&
               Objects.equals(city, address.city);
    }

    @Override
    public int hashCode() {
        return Objects.hash(addressLine1, addressLine2, city);
    }


    @Override
    public String toString() {
        return "Address{" +
               "addressLine1='" + addressLine1 + '\'' +
               ", addressLine2='" + addressLine2 + '\'' +
               ", city='" + city + '\'' +
               '}';
    }
}


@Override
public String toString() {
    return "Person{" +
           "name='" + name + '\'' +
           ", address=" + address +
           '}';
}

2020-04-27 23:16:47

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一码平川MACHEL

想将地址数据封装在一个对象中。这样，“Person”不等于其地址，你可以进行更精细的搜索。另外，你可以通过这种方式分离问题。

我在这里写了一个示例：

import java.util.ArrayList; import java.util.List; import java.util.Objects; import java.util.stream.Collectors;

public class Person {

public static void main(String[] args) {


    // what we're searching for
    Address address = new Address("123 N 3rd st", "east ohg", "this-city");

    // init
    List<Person> persons = new ArrayList<>();
    persons.add(new Person("Jim", "123 N 56 st", "east ohg", "this-city"));
    persons.add(new Person("Kyle", "145 N 67th st", "east ohg", "this-city"));
    persons.add(new Person("Sam", "12 beach av", "east ohg", "this-city"));
    persons.add(new Person("Tracy", "123 N 3rd st", "east ohg", "this-city"));
    persons.add(new Person("Ashley", "123 N 3rd st", "east ohg", "this-city"));


    // search
    List<Person> people = persons.stream().filter(person -> person.address.equals(address)).collect(Collectors.toList());

    people.forEach(System.out::println);


}

String name;
Address address;

public Person(String name,
              String addressLine1,
              String addressLine2,
              String city) {
    this.name = name;
    this.address = new Address(addressLine1,
                               addressLine2,
                               city);
}

private static final class Address {
    String addressLine1;
    String addressLine2;
    String city;


    public Address(String addressLine1, String addressLine2, String city) {
        this.addressLine1 = addressLine1;
        this.addressLine2 = addressLine2;
        this.city = city;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Address address = (Address) o;
        return Objects.equals(addressLine1, address.addressLine1) &&
               Objects.equals(addressLine2, address.addressLine2) &&
               Objects.equals(city, address.city);
    }

    @Override
    public int hashCode() {
        return Objects.hash(addressLine1, addressLine2, city);
    }


    @Override
    public String toString() {
        return "Address{" +
               "addressLine1='" + addressLine1 + '\'' +
               ", addressLine2='" + addressLine2 + '\'' +
               ", city='" + city + '\'' +
               '}';
    }
}


@Override
public String toString() {
    return "Person{" +
           "name='" + name + '\'' +
           ", address=" + address +
           '}';
}

}

2019-10-16 18:35:13

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