避免对象中的参数参数具有相同的值

4回答

吃鸡游戏

您可以通过添加串联的姓名、性别来创建静态字符串哈希集。class YourClass {   public static Set<String> studentSet = new HashSet<>();   public static void addStudent(String name, String gender) {     YourClass.studentSet.add(name + "," + gender);   }   public static Boolean studentExists(String name, String gender) {     return YourClass.studentSet.constains(name + "," + gender);}因此，您的 HashSet 中的数据将类似于 Tom,male 、Tom,female、John,male 。class Student {...public Student(String name, String gender) {    this.name = name;    this.gender = gender;    YourClass.addStudent(name, gender);  }}在创建 Student 实例时，您可以检查 HashSet 中是否没有 Name、Gender，然后实例化和对象。if(!YourClass.studentExists(name, gender)) {    Student student = new Student(name, gender);}我希望这能解决你的问题

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暮色呼如

您可以创建一个类来控制对象的创建 - 基本上使用享元模式。步骤 1. 将 Student 包的构造函数设置为私有public class Student {    Student(String name, String gender) {    ...步骤2.在Student中实现equals方法   public boolean equals (Object other) {       if (!(other instanceof Student)) return false;       Student otherStudent = (Student) other;       return Objects.equals(otherStudent.getName(), this.getName()) && Objects.equals(otherStudent.getGender(), this.getGender());   }步骤 3. 在同一包中实现 Student 对象池public class StudentPool {    private List<Student> students = new ArrayList<>();    public Student getOrCreate(String name, String gender) {        Student student = new Student(name, gender);        return students.stream()                .filter(s -> Objects.equals(s, student))                .findFirst()                .orElseGet(() -> {                    students.add(student);                    return student;                });    }    public List<Student> get(String name) {        return students.stream()                .filter(student -> Objects.equals(student.getName(), name))                .collect(Collectors.toList());    }}

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婷婷同学_

假设您所说的“值”指的是学生的姓名，我建议您编写一个小函数，如果该姓名已被占用，该函数将返回 true。为此，您可以将所有“学生”存储在 ArrayList 中：ArrayList<Student> students = new ArrayList<Student>();现在您可以将学生添加到此 ArrayList 中，如下所示：private boolean nameIsAlreadyTaken(ArrayList<Student> students, String newName){    for (int i = 0; i < student.size(); i++){        if(students.get(i).getName().equals(newName)){            return true;        }    }    return false;}（您需要在学生类中定义一个 getName() 函数才能使其工作。）那么你可以这样做：字符串 newName = "迈克尔"; String newGender = "男";if (!nameIsAlreadyTaken(students, newName)){students.add(new Student(newName, newGender));} else{    //something you want to to if the name is already taken}您可以在不将 Students-ArrayList 传递给函数的情况下执行此操作，但这取决于您。

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偶然的你

我想说你需要重写Student和equals方法hashCode，然后检查构造函数是否存在这样的学生。关于这一点的好答案：链接。import java.util.*;public class Student {    private static final Set<Student> REGISTERED_STUDENTS = new HashSet<>();    private String name;    private String gender;    public static Collection<Student> getRegisteredStudents() {        return Collections.unmodifiableCollection(REGISTERED_STUDENTS);    }    public Student(final String name, final String gender) {        this.name = name;        this.gender = gender;        if (REGISTERED_STUDENTS.contains(this))            throw DuplicateStudentException();        REGISTERED_STUDENTS.add(this);    }    @Override    public int hashCode() {        return Objects.hash(name, gender);    }    @Override    public boolean equals(final Object o) {        if (this == o) return true;        if (!(o instanceof Student)) return false;        final Student student = (Student) o;        return Objects.equals(name, student.name) && Objects.equals(gender, student.gender);    }}请注意，这个示例不是线程安全的，并且使用了在构造函数中抛出异常的有争议的解决方案。您可能需要一个工厂方法和ConcurrentSkipListSet/或另一个线程安全集合，如下所示：class Student {    private static final Set<Student> REGISTERED_STUDENTS = new ConcurrentSkipListSet<>(Comparator.comparing(Student::getName).thenComparing(Student::getGender));    private String name;    private String gender;    public static Set<Student> getRegisteredStudents() {        return Collections.unmodifiableSet(REGISTERED_STUDENTS);    }    public static void addStudent(final String name, final String gender) {        Student probablyExists = new Student(name, gender);        REGISTERED_STUDENTS.add(probablyExists);    }    private Student(final String name, final String gender) {        this.name = name;        this.gender = gender;    }    public String getName() {        return name;    }    public String getGender() {        return gender;    }    @Override    public int hashCode() {        return Objects.hash(name, gender);    }    @Override    public boolean equals(final Object o) {        if (this == o) return true;        if (!(o instanceof Student)) return false;        final Student student = (Student) o;        return Objects.equals(name, student.name) && Objects.equals(gender, student.gender);    }}

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