Lecture 6: Design, Debugging, Interfaces

A good program

• Correct / no errors
• Easy to understand
• Easy to modify / extend
• Good performance(speed)
• writing code with a consistent way makes it easier to write and understand

Good Naming

● variables: Nouns, lowercase first letter, capitals separating words ● Methods: Verbs, then same with variavles ● Classed: Nouns, uppercase first letter.

Good Class Design

● Make fields and methods private by default ● Only make methods public if you need to ● If you need access to a field, create a method; 将field字段private是之前没有考虑的 public int getBar(){return bar;}

Debugging

Design: Pseudocode（伪代码）

• A high-level, understandable description of what a program is supposed to do
• Don't worry about the details, worry about the structure.

这里提到了一种方法叫作区间测试Interval Testing，其用于检查程序在特定输入区间内的行为。

在设计程序的时候，可以为对象或者程序工作流程进行视觉上的一些设计，不要特别关注特定的符号表示是怎么样的，只需要对你合理即可。这里我理解的意思就像slides中展示的这副图片一样，进行可视化的一些设计就会清晰很多：

可以考虑重要的输入和边界值等来进行一些测试，尽早发现程序的问题。

Assertions是一种很好用的工具/语法，以前我自己写程序倒是很少用到过，以后会逐渐尝试这种工具。

Interfaces

介绍了使用methods的好处，比如封装和复用性，还可以隐藏具体实现只对外暴露接口，使用的人也无需知道具体实现

Java Interface

• Manipulate objects, without knowing how they work
• Useful when you have similar but not identical objects
• Useful when you want to use code written by others
• Set of classes that share methods
• declare an interface with the common methods
• Interface only have methods, only definition (called signatures) without codes
• A class can implement any number of interface