Java - 最终和有效最终之间的区别

... 从JavaSE8开始，局部类可以访问封闭块的局部变量和参数，这些变量和参数是final或实际上是final.A variable or parameter whose value is never changed after it is initialized is effectively final.

例如，假设变量numberLength未声明为final，并在PhoneNumber构造函数中添加标记的赋值语句:

public class OutterClass {  

  int numberLength; // <== not *final*

  class PhoneNumber {

    PhoneNumber(String phoneNumber) {
        numberLength = 7;   // <== assignment to numberLength
        String currentNumber = phoneNumber.replaceAll(
            regularExpression, "");
        if (currentNumber.length() == numberLength)
            formattedPhoneNumber = currentNumber;
        else
            formattedPhoneNumber = null;
     }

  ...

  }

...

}

由于这个赋值语句，变量numberLength实际上不再是最终的.As a result, the Java compiler generates an error message similar to "local variables referenced from an inner class must be final or effectively final"，其中内部类PhoneNumbertry 访问numberLength变量:

http://codeinventions.blogspot.in/2014/07/difference-between-final-and.html

http://docs.oracle.com/javase/tutorial/java/javaOO/localclasses.html