Constants in Java SE 038 programs and when to use constants

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Constants in Java SE 038 programs and when to use constants

1. Constants in the program and in what occasions to use constants

(1) The naming rules for constants in java: the letters of all words are capitalized, if there are multiple words, use underscores to connect them.

例如：public static final int AGE_OF_PERSON = 20;

(2) Why are static and final often used together?

Reason: If static is not added, then this value is only final, and every object has this value. The value in each object cannot be changed. If static is added, no matter how many objects are generated, there is only one constant value, and it cannot be changed. Shared by multiple objects, that is, read it together. For 10 objects, one is to generate 10 constants, and the other is to generate 1 constant. Which is better? One is definitely better. Therefore, static is usually added to the constant to modify it.

(3) What is the role of constants?

(4) The static keyword is usually added when declaring final constants in Java, so that each instance of the object will access a unique constant value.

In this way, each instance of the object will access a unique constant value.