ENUM存储（内存等）

Question

I was just asking myself a little question, and I'm not sure if I can find the right answer to this:

If I use an ENUM in Java, with an own constructor (and many, many, maaaaany parameters) - are those stored in Memory every time the program gets executed, or are they only 'loaded' in Memory, if they get used?

What I mean is, if I have an ENUM with 400 entries, and only use one of the entries - are all others still present in Memory?

some pseudocode:

public enum Type {
    ENTRY_A(val1, val2, val3, val4, new Object(val5, val6, val7, ...)),
    ENTRY_B(val1, val2, val3, val4, new Object(val5, val6, val7, ...)),
    ENTRY_C(val1, val2, val3, val4, new Object(val5, val6, val7, ...)),
    ...
}

If I only use ENTRY_A, and dont touch ENTRY_B, ENTRY_C, etc - how will Java handle that exactly?

Thanks for the Answer - and yes, this is mainly curiousity

Answer 1

Yes everything will be loaded to memory even though you use only one ENUM constant.

Enum is special type of class and all fields are constants, so when you load the ENUM, then itself it loads everything to memory.

Answer 2

第一次使用枚举时，将触发类初始化，所有值都将被创建并存储在内存中，就像任何其他类一样。

Answer 3

You could always try it by yourself. Just put for example System.println("test") in the constructor of your enum and empirically embrace the results.