Variables that final can modify in Java

Here we only discuss the variables that final can modify, not methods and classes.

1. Final can modify variables: class variables, member variables, and local variables.

2. It should be noted that:

(1) Differences: modify class variables and member variables: initial values must be assigned when declaring variables;

Modified local variable: it does not need to be assigned an initial value. Because you must assign a value to a local variable before using it, it is illegal to directly call an unassigned local variable, so the local variable modified by final can be declared without assignment.

(2) Same point: variables modified by final can only be assigned once.

3. Example code:

错误提示:变量a1可能没有被初始化
    //final static int a2;//错误提示:变量a2可能没有被初始化
    final int a3=1;
    final static int a4=2;
    private void testFinal(){
        final int a5;
        a5=1;
        //a5=2;//错误提示:变量a5可能已经被赋值.
    }
}