java - 你把这个称作什么？

Question

是否有此技术的名称(方法调用返回对象，在同一行上对其进行另一个方法调用)？

String pAID = commonAssets.getApplicationServerSettings().getSetting("plivoAuthID");

代替

ApplicationServerSettings applicationServerSettings = commonAssets.getApplicationServerSettings();
String pAID = applicationServerSettings.getSetting("plivoAuthID");

此外，当我执行第一个时，Eclipse 不会提示我导入类 ApplicationServerSettings，但如果我使用第二个代码样式，它会提示。

另外，这两种风格仅仅是偏好吗？

Answer 1

该技术称为 method chaining .

String pAID = commonAssets.getApplicationServerSettings().getSetting("plivoAuthID");

来自维基的定义:

Method chaining, also known as named parameter idiom, is a common syntax for invoking multiple method calls in object-oriented programming languages. Each method returns an object, allowing the calls to be chained together in a single statement without requiring variables to store the intermediate results.[1] Local variable declarations are syntactic sugar because of the difficulty humans have with deeply nested method calls.[2][3] A method chain is also known as a train wreck due to the increase in the number of methods that come one after another in the same line that occurs as more methods are chained together[4] even though line breaks are often added between methods.

你的第二个问题:

此外，当我执行第一个时，Eclipse 不会提示我导入类 ApplicationServerSettings，但如果我使用第二个代码样式，它会提示。

• 再次从定义“每个方法返回一个对象，允许调用在一个语句中链接在一起，而不需要变量来存储中间结果。”这就是它不提示你的原因导入类 ApplicationServerSettings。

另一个看起来更简单的例子(除了你介绍的want):

看看维基示例:

class Person {
    private String name;
    private int age;

    // In addition to having the side-effect of setting the attributes in question,
    // the setters return "this" (the current Person object) to allow for further chained method calls.

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

    public Person setAge(int age) {
        this.age = age;
        return this;
    }

    public void introduce() {
        System.out.println("Hello, my name is " + name + " and I am " + age + " years old.");
    }

    // Usage:
    public static void main(String[] args) {
        Person person = new Person();
        // Output: Hello, my name is Peter and I am 21 years old.
        person.setName("Peter").setAge(21).introduce();
    }
}