I tried to make an Android application with MVC now (Java)

Introduction

This is the Android version (Java) of this.

My Android experience is at a level where I can make something that works. I made iOS, so why not Android !!

I don't know much about Android, so I made it with MVC for the time being. I did a quick search for MVC on Android, but I wasn't sure, so I've put it on iOS quite a bit.

I made it with the feeling that it is probably like this, so I would appreciate it if you could point out if it was wrong.

The iOS guy I made earlier

• I made an iOS app with MVC now (Objective-C)
• I made an iOS app with MVC now (Swift)

environment

macOS High Sierra version 10.13.2

Android Studio 3.2.1

What to make

If there are too few functions, it will be difficult to understand the difference even if you make it with various designs, so this time I will make the following application.

App requirements

An application that displays the weather of each prefecture using livedoor weather Web API (not available for commercial use).

The target is Android 5.0 or later.

function

Lists 47 prefectures and displays the weather for the selected prefectures today, tomorrow, and the day after tomorrow.

• The display of the prefecture list can be narrowed down by each region.
• You can register your prefecture's favorites (memorize on your device)
• You can narrow down the list of prefectures by favorite.

screen structure

Two screens, a prefecture list screen and a detail screen. (3 screens including splash)

Ignore the splash screen. (Because it is not separated by MVC)

Prefecture list screen

• List 47 prefectures
• Acquire weather information by communication by selecting a prefecture and transition to the details screen (does not transition when an error occurs)
• Tap the star mark to delete your favorites
• Show only favorites Check the checkbox to show only favorites
• Display a pop like the image below with the refine button in the region

• The list display is narrowed down by switching the check.

Details screen

• Display the selected prefecture name
• Display the weather for the selected prefecture today, tomorrow, and the day after tomorrow.
• The displayed contents display 5 items: date, icon, weather, maximum temperature, and minimum temperature.
• Re-acquire weather information by communication with the reload button on the upper right

Glossary

I think that one of the reasons why there are differences in recognition among individuals such as MVC is that the meaning of katakana is ambiguous.

I'm researching MVC and I'm not sure about business logic after all, so I'll write about the meaning of Katakana in this article. (It may be different from the actual meaning ...)

What is business logic?

In the explanation of here, it is "the part of the system that performs system-specific processing".

The following applies to this app

• Narrowing down in each region
• Favorite registration
• Narrow down your favorites
• Get weather information

What is a layout?

The following applies to this app

• Placement of parts such as View
• Displaying a list of prefectures
• Display of weather information

What is a user action?

The following applies to this app

• Button tap
• Cell tap

Each design

I gave what I made to here.

What I made this time is Okhttp3 for communication and JSONExport for creating a class that handles JSON data. I used.

I will write my perception of each design, the number of files, the number of lines of Activity, and the impression I made.

Almost Activity

For the time being, I made it with Activity without thinking about anything this

number of files

• java file: 18
• xml file: 21

Number of lines of Activity (including comments)

• Prefecture list screen: 325 lines
• Details screen: 287 lines

Impressions made

The number of files is small and the development speed is fast. Each class has about 300 lines, so I think this is also possible for this scale. Since the process is written in the Adapter, I feel that the number of lines of Activity has decreased.

MVC

The project is this

recognition

Model (Applicable: Object)

• Data retention
• Business logic
• Notify Controller of data change

View (Applicable: Fragment, View, xml)

• Screen layout
• Notify Controller of user action

Controller (Applicable: Activity)

• Mediation between Model and View
• Update model data by receiving user action notification from View
• Update View display by receiving data update notification from Model

number of files

• java file: 23
• xml file: 25

Number of lines of Activity (including comments)

• Prefecture list screen: 175 lines
• Details screen: 144 lines

Impressions made

For the time being, I made Fragment as View. Getting the button event and passing the List to the Adapter is a bit annoying, but it's slimmer. Creating a Model makes it easier to save with onSaveInstanceState. The display process of PopupWindow has increased the number of lines of Activity considerably, so if you can divide it a little more, you may be able to make it a little slimmer. For screens with many parts, `` `findViewById``` can be grouped into Fragment, so Activity is quite refreshing, so I think it's quite easy to use.

Other

Other points that deviate from the main point but were worrisome

• Should strings.xml be created for each screen?
• Should styles.xml be created for each screen?
• Should colors.xml be created for each screen?
• Should the default character display of TextView in layout xml be described in strings.xml? (Characters to be displayed for the time being to see the layout)
• Is it old to prefix m to member variables?

at the end

There were quite a lot of parts that I wasn't used to when I made it like iOS. When I used Activity with the same feeling as ViewController, it was a bug. Activity and Fragment die so often. It feels unpleasant to have a List in the Adapter as well, but I feel that this can't be helped.

I wrote this article because I wanted someone to give me an opinion, so I would appreciate it if you could give me an opinion. If you think "this is the strongest design!", Please try to make an app with the above specifications.

If you feel like it, I'll try making it in Kotlin. I feel that Kotlin is the mainstream these days ...