java - 在Java中: How do I create a class that can be initialized and call its methods in one statement?

Question

这个问题已经有答案了:

How to achieve method chaining in Java? (4 个回答)

已关闭 7 年前。

在使用 Google 服务库时，我在 Android 编程中经常看到一种编码风格，它们在初始化类的实例后使用点来调用方法。

例如，假设我有一个 Person 类:

public class Person {
    private String firstName;
    private String lastName;    
    private String occupation;
    private String primarySkill;
    private String secondarySkill;

/* ******************
 *   CONSTRUCTOR
 * ******************/
    public Person(String firstName, String lastName) {
        setFirstName(firstName);
        setLastName(lastName);
    }

/* ******************
 *     MUTATORS
 * ******************/
    // firstName Setter:
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    // lastName Setter:
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    // occupation Adder:
    public void addOccupation(String occupation) {
        this.occupation = occupation;
    }

    // primarySkill Adder:
    public void addPrimarySkill(String primarySkill) {
        this.primarySkill = primarySkill;
    }

    // secondarySkill Adder:
    public void addSecondarySkill(String secondarySkill) {
        this.secondarySkill = secondarySkill;
    }   
}

现在，当我创建此类的实例时，我希望能够执行以下操作:

Person bob = new Person("Bob", "Anderson")
            .addOccupation("Student")
            .addPrimarySkill("Java")
            .addSecondarySkill("SQL");

但是这给了我语法错误。我怎样才能构建一个可以让我做到这一点的类？

Answer 1

您正在寻找的称为方法链。修改您的 setter 以返回 this:

// occupation Adder:
public Person addOccupation(String occupation) {
    this.occupation = occupation;
    return this;
}