在 Java 16 之前构建此类需 40 行代码，如下：

package com.davidemarino;

import java.util.Objects;

public final class PersonClass {
  private final String firstName;
  private final String lastName;

  public PersonClass(String firstName, String lastName) {
      this.firstName = firstName;
      this.lastName = lastName;
  }

  public String getFirstName() {
      return firstName;
  }

  public String getLastName() {
      return lastName;
  }

  @Override
  public boolean equals(Object o) {
      if (o == null || getClass()!= o.getClass()) return false;
      PersonClass that = (PersonClass) o;
      return Objects.equals(firstName, that.firstName) && Objects.equals(lastName, that.lastName);
  }

  @Override
  public int hashCode() {
      return Objects.hash(firstName, lastName);
  }

  @Override
  public String toString() {
      return "PersonClass{" +
              "firstName='" + firstName + '\'' +
              ", lastName='" + lastName + '\'' +
              '}';
  }
}

可按如下使用：

package com.davidemarino;

public class Main {
  public static void main(String[] args) {
      PersonClass personClass = new PersonClass("John", "Doe");
      System.out.println("First name: " + personClass.getFirstName());
      System.out.println("Last name: " + personClass.getLastName());
      System.out.println(personClass);
  }
}

Java 16 后可使用record关键字定义此类类，如下：

package com.davidemarino;

public record PersonRecord(String firstName, String lastName) { }

使用方式如下：

package com.davidemarino;

public class Main {
  public static void main(String[] args) {
      PersonClass personClass = new PersonClass("John", "Doe");
      System.out.println("First name: " + personClass.getFirstName());
      System.out.println("Last name: " + personClass.getLastName());
      System.out.println(personClass);

      PersonRecord personRecord = new PersonRecord("John", "Doe");
      System.out.println("First name: " + personRecord.firstName());
      System.out.println("Last name: " + personRecord.lastName());
      System.out.println(personRecord);
  }
}

区别在于获取方法的命名约定不同，传统方式为getFirstName()和getLastName()，record方式为firstName()和lastName()。

若有可变对象字段，如在PersonClass中添加List<String> preferences字段，传统方式需在构造函数和获取方法中创建字段副本，如下：

package com.davidemarino;

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

public class PersonClass {
  private final String firstName;
  private final String lastName;
  private final List<String> preferences;
  
  public PersonClass(String firstName, String lastName, List<String> preferences) {
      this.firstName = firstName;
      this.lastName = lastName;
      this.preferences = new ArrayList<>(preferences);
  }

  public String getFirstName() {
      return firstName;
  }

  public String getLastName() {
      return lastName;
  }

  public List<String> getPreferences() {
      return new ArrayList<>(preferences);
  }

  @Override
  public boolean equals(Object o) {
      if (o == null || getClass()!= o.getClass()) return false;
      PersonClass that = (PersonClass) o;
      return Objects.equals(firstName, that.firstName) && Objects.equals(lastName, that.lastName) && Objects.equals(preferences, that.preferences);
  }

  @Override
  public int hashCode() {
      return Objects.hash(firstName, lastName, preferences);
  }

  @Override
  public String toString() {
      return "PersonClass{" +
              "firstName='" + firstName + '\'' +
              ", lastName='" + lastName + '\'' +
              ", preferences=" + preferences +
              '}';
  }
}

使用record方式如下：

package com.davidemarino;

import java.util.ArrayList;
import java.util.List;

public record PersonRecord(String firstName, String lastName, List<String> preferences) {
  public PersonRecord {
      preferences = new ArrayList<>(preferences);
  }

  public List<String> preferences() {
      return new ArrayList<>(preferences);
}

此部分代码称为紧凑规范构造函数，相当于以下标准构造函数：

  public PersonRecord(String firstName, String lastName, List<String> preferences) {
      preferences = new ArrayList<>(preferences);
      this.firstName = firstName;
      this.lastName = lastName;
      this.preferences = preferences;
  }