代码之家 › 专栏 › 技术社区 › Dawid

java构造函数中的许多参数[重复]

constructor java

Dawid · 技术社区 · 7 年前

嗨,我是java的初学者。

像在我的BookLibrary程序中那样,用许多参数创建构造函数是一种好方法吗?

public class Book implements Serializable {

private String title;
private String directorName;
private String directorSurname;
private String type;
private int issueYear;
private List<String> actorNames;
private List<String> actorSurnames;
private Tuple<String, String> directorFullName;


public Book(String title, String directorName, String directorSurname, String type, int issueYear,
            List<String> actorNames, List<String> actorSurnames, Tuple<String, String> directorFullName){
    this.title = title;
    this.directorName = directorName;
    this.directorSurname = directorSurname;
    this.type = type;
    this.issueYear = issueYear;
    this.actorNames = actorNames;
    this.actorSurnames = actorSurnames;
    this.directorFullName = directorFullName;
}

或者有没有更好的想法来创建这样一个构造函数?

2 回复 | 直到 7 年前

Ralf Kleberhoff 7 年前

正如其他人在评论中所说,使用Builder模式将是一种选择。但如果操作不当,则会带来创建不完整对象的风险。

但是有更多的方法可以改进您的设计。E、 g.你传递名字和姓氏(如果是导演,则传递全名-为什么只有在那里?)作为单独的字符串。我会创建一个 PersonName 类,该类封装了这些不同的命名元素,因此您的构造函数成为:

public Book(String title, 
            PersonName directorName, 
            String type, 
            int issueYear,
            List<PersonName> actors) {
    ...
}

外观更好,命名问题更一致。

当然,将该类重命名为 Movie 而不是 Book 。

Abzelhan 7 年前

创建具有3个以上参数的构造函数不是最佳做法。因为您需要知道每个参数的顺序。我可以建议您以这种方式使用getter和setter(对于标题类别字段):

public String getTitle() {
    return title;
}

public Book setTitle(String title) {
    this.title = title;
    return this;
}

通过此结构,您可以在创建新实例的同时创建非常漂亮的构造:

Book book = new Book()
            .setTitle("Book")
            .setType("Comedy")
            .setActorNames(Arrays.asList("Abzal"));

类的完整重构版本:

public class Book implements Serializable {
private String title;
private String directorName;
private String directorSurname;
private String type;
private int issueYear;
private List<String> actorNames;
private List<String> actorSurnames;
private Tuple<String, String> directorFullName;

public Book() {
}


public String getTitle() {
    return title;
}

public Book setTitle(String title) {
    this.title = title;
    return this;
}

public String getDirectorName() {
    return directorName;
}

public Book setDirectorName(String directorName) {
    this.directorName = directorName;
    return this;
}

public String getDirectorSurname() {
    return directorSurname;
}

public Book setDirectorSurname(String directorSurname) {
    this.directorSurname = directorSurname;
    return this;
}

public String getType() {
    return type;
}

public Book setType(String type) {
    this.type = type;
    return this;
}

public int getIssueYear() {
    return issueYear;
}

public Book setIssueYear(int issueYear) {
    this.issueYear = issueYear;
    return this;
}

public List<String> getActorNames() {
    return actorNames;
}

public Book setActorNames(List<String> actorNames) {
    this.actorNames = actorNames;
    return this;
}

public List<String> getActorSurnames() {
    return actorSurnames;
}

public Book setActorSurnames(List<String> actorSurnames) {
    this.actorSurnames = actorSurnames;
    return this;
}

public Tuple<String, String> getDirectorFullName() {
    return directorFullName;
}

public Book setDirectorFullName(Tuple<String, String> directorFullName) {
    this.directorFullName = directorFullName;
    return this;
}

}

有一个好的编码!