Java中的客户端方法是什么？

Question

I'm relatively new to Java and trying to learn more about the terminology. As I was reading, I came across the term client methods in a discussion about public, private and static variables.

Here are a two questions that I have regarding this term:

• Are client methods simply all methods that are not declared within a specific file? Say I have two files, one called File1.java and the other File2.java . If File2.java contained a method called printText , would that be considered a client method from the perspective of File1 ?
• Why are they called " client " methods, what exactly defines a client? Are there client variables too?

Edit: As a reference, I saw this term in the current latest edition of the Barron's AP Computer Science A book , here is a direct quote:

The variable OVERDRAWN_PENALTY is an example in the BankAccount class. Since the variable is public, it can be used in any client method. [...] A client method would refer to the variable as BankAccount.OVERDRAWN_PENALTY. In its own class it is referred to as simply OVERDRAWN_PENALTY.

Re-Edit , this part was included a bit before the quote above:

Similarly public methods are accessible to all client programs. Clients, however, are not privy to the class implementation and may not access the private instance variables and private methods of the class.

Answer 1

好的，根据您的评论，本书的这一部分似乎将术语“ client methods用作“使用该类的方法/不在此类/程序包/库中的client methods ”的缩写。

Answer 2

I think it just means "exposed to a client". Think about an API, it can contain any number of methods of various visibility modifiers, but the only ones you can directly use as a "client" are those that are public .

After reading that a few times, though, it does seem to say a method not within the same class that accesses the current class is considered a "client method".

Answer 3

The word "client" is typically used to connote "a user of some other system or service."

When one speaks of a client process , for example, this is meant to indicate a process that accesses, uses, or consumes services that are provided by some corresponding server program or process .

This language has carried over, more generally, into discussions of APIs. A "client" of an API is a program (often written by a different programmer) that accesses the services that are defined by the contract of that API. As an aside, in Java an API is formed by all the members of the classes and interfaces which can be accessed by classes in different packages (ie the exported members define the API).

In the paragraph provided:

The variable OVERDRAWN_PENALTY is an example in the BankAccount class. Since the variable is public, it can be used in any client method. [...] A client method would refer to the variable as BankAccount.OVERDRAWN_PENALTY. In its own class it is referred to as simply OVERDRAWN_PENALTY.

The client method refers to a method (probably written by someone else) that accesses the services of the BankAccount class, in this case the public variable in the class.

Answer 4

The term "client" for users of an API (eg a method) is quite common to me. So if it's a method that uses another method the first one is a client to the latter.

It's completely unrelated to "network clients" in this context.

One – rather authoritative – source for this is the book "Effective Java" by Joshua Bloch.

Let me quote two examples:

The normal way for a class to allow a client to obtain an instance of itself is to provide a public constructor.

and:

In short, the telescoping constructor pattern works, but it is hard to write client code when there are many parameters, and harder still to read it.

You may easily come up with "client method" then I think.