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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.

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.

The parts of a method signature and a call that matches it

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.

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).