Lecture 12

Fall 2018

Narges Norouzi

Summary of mid-quarter survey

Summary

• More in-class coding demos
• More practice problems
• Bonus programming questions
• Going slower in the lecture

final

Final

• Methods, classes, and variables can be defined as final.

• Let’s look at what it means in each scenario

Final method

• You cannot override final methods in subclasses

• Private methods are implicitly final

• Static methods are implicitly final

   

Final variable

• The value of final variable will remain constant

• You cannot change the value of final variables

• You should immediately assign a value to final variables

• Different types of final variables

  • Final parameter

  • Final local variable

  • Final instance variable

  • Final static variable

Key notes about final variables

• An uninitialized final field of a class must be definitely assigned in every constructor of the class

• An uninitialized final static variable must be definitely assigned in a static initializer of the class in which it is declared

Final classes

• You cannot inherit from final classes

  • No class can extend final classes

Review (1)

• Final data:

  • Constant

  • Local variables or instance variables

  • Primitives —> constant values

  • Objects —> constant references

• A compile-time constant that won’t ever change
• A value initialized at run time that you don’t want changed

Review (2)

• Final Methods

  • No override

• Final Class
  • No subclass

Zybooks chapters we covered

• Section 2.9: final variables (but we covered more)