在分配了最终变量之后，是否可以更改最终变量？

Question

import java.util.Scanner;

public class OnlineShop {

  public static void main (String[]args) {

    final double subAmmount;

    subAmmount = subAmmount + Array[i];
}

错误：

The final local variable subAmmount may have already been assigned

Answer 1

因为subAmount未声明为static，所以必须在声明时将其初始化。所以你应该有这样的东西

import java.util.Scanner;

public class OnlineShop {

  public static void main (String[]args) {

    final double subAmmount = Array[i]; // Assuming Array[i] is defined somewhere
}

如果要在初始化后进行声明，则可以：

import java.util.Scanner;

public class OnlineShop {

  static final double subAmmount;

  public static void main (String[]args) {

    subAmmount = subAmmount + Array[i]; // Assuming Array[i] is defined somewhere
}

检查此link以获得final关键字的更多细微差别

Answer 2

“ subAmmount”尚未初始化/设置，因此您不能向其自身添加subAmmount，因为它不等于任何值。