メソッドシグネチャ

語彙

English	意味
method/ˈmeθəd/	メソッド
signature/ˈsɪɡnɪtʃə/	シグネチャ
parameter/pəˈræmɪtə/	引数（形式）
argument/ˈɑːɡjuːmənt/	実引数
overloading/ˌəʊvəˈləʊdɪŋ/	オーバーロード

English

A method's name tag

A method 方法 is a named block of code you can call to do a job.
Its signature 方法签名 is the part that identifies it: the name plus the parameter list.
Example signature: max(int a, int b) — name max, two int parameters.
The signature is how Java knows which method you mean when you call one.

English

Parameters and arguments

A parameter 形参 is a variable in the method's definition: int a in max(int a, int b).
An argument 实参 is the actual value you pass when calling: max(5, 9) passes 5 and 9.
Arguments are matched to parameters by position, left to right.
Inside the method, the parameters hold copies of the arguments.

English

The return type

A method's return type says what kind of value it hands back.
public int max(int a, int b) returns an int; a void method returns nothing.
Use return value; to send a result back to the caller.
The return type is part of the header but not part of the signature.

English

Overloading: same name, different signature

Java allows overloading 重载: several methods with the same name but different parameter lists.
print(int x) and print(String s) are distinct — the argument types tell them apart.
The compiler picks the version whose signature matches your arguments.
Overloading only works when the signatures differ (return type alone is not enough).

English

Watch out

The signature is name + parameter list — the return type is NOT part of it. That's why you can't overload two methods that differ only by return type. Parameters live in the definition; arguments are the values you pass, matched by position. Passing the wrong number or type of arguments is a compile error.

English

Example

Calling max:

Definition: public int max(int a, int b) { return a > b ? a : b; }
Call: int m = max(5, 9); → argument 5 → parameter a, 9 → b.
The method returns 9, stored in m.

English

Key idea

A method signature is its name plus parameter list (the return type is not part of it). Parameters are the definition's variables; arguments are the values passed at a call, matched by position. Overloading allows the same name with different parameter lists, distinguished by the arguments.

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