final keyword meanings:
Surface meaning: can not change the final.
Like const keyword in C language, it refers to the amount can not be changed.
But there is a difference of static variables, static variables refers to only one storage space, the value can change.
The final effect:
1. Modified class: the final modified class can not be inherited;
2. modification methods: final modified method can not be rewritten;
3. modified variables: the final modified variable must be initialized, and can not be re-assigned after the initial value;
Why modified final variables?
In fact, if a data is fixed, then use this data directly in the program on it,
But this reading is poor, so they give a name to the data.
And the value of this variable name can not be changed, so plus final fixed.