CS442 Solution

CS 442 Mobile Applications
Development (Android Section)

CS 442: Mobile Applications Development
Assignment 5 – News Aggregator (400 pts)
Uses: Drawer Layout, ViewPager2, Adapters, Internet, APIs, Dynamic Menus, Implied Intents App Highlights:
• This app displays current news articles from a wide variety of news sources covering a range of news categories.
• NewsAPI.org will be used to acquire the news sources and news articles.
• Selecting a news source (i.e., CNN, Time, etc.) will display up to 10 top stories from that news source.
• Selecting a news topic will limit the news source choices to only those offering that topic of news.
• News articles are viewed by swiping right to read the next article, and left to go back to the previous article
• You will not need to develop separate landscape layouts.
• The user can go to the complete extended article on the news source’s website by clicking on the article title, text, or image content.
• You must add a professional looking launcher icon to your app.





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CS 442 Mobile Applications
Development (Android Section)


Menu Behavior Examples:
• Filter News Sources by Topic (technology) – then view the news from source “Engadget”:





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CS 442 Mobile Applications
Development (Android Section)

• Filter News Sources by Topic (business) – then view the news from source “Handelsblatt”:





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CS 442 Mobile Applications
Development (Android Section)

A) News Data:
Acquiring news source and news article data will be done via the NewsAPI.org news aggregation service. This service allows you to download news sources and news articles (by news source)
NOTE: You MUST sign up get an API key in order to access the NewsAPI.org services. Your API KEY must be supplied with NewsAPI.org queries. You can do this by registering at:
https://newsapi.org/register
Register with an email and a new password and agree to the terms and click Submit to register and get your API key (the key is displayed to you right after you click the Submit button).
The API:
The NewsAPI.org service offers 2 API calls – one to get news sources (organizations offering news – CNN, Time, etc.) and one to get top news articles from a selected news source.
1) News Sources Query Format (to be used in our assignment):
To get all sources: https://newsapi.org/v2/sources?apiKey=________ For example, if your API Key was “ABC123xyz”, the URL would be: https://newsapi.org/v2/sources?apiKey=ABC123xyz
The News Source Query response is sent in JSON format (described in the next section).
2) News Article Query Format (to be used in our assignment):
To get top articles for a News Source: https://newsapi.org/v2/top-headlines?sources=______&apiKey=______ For example, if your API Key was “ABC123xyz” and you wanted “cnn” news, the URL would be:
https://newsapi.org/v2/top-headlines?sources=cnn&apiKey= ABC123xyz The News Article Query response is sent in JSON format (described in the next section).
NOTE: This API requires the “User-Agent” request property be provided with your
JsonObjectRequest objects. The value this property is set to does not matter, but it must be set. See the example below (red/bold is new):
JsonObjectRequest jsonObjectRequest =
new JsonObjectRequest(Request.Method.GET, url.toString(), null, listener, error) {
@Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> headers = new HashMap<>(); headers.put("User-Agent", ""); return headers;
}
};


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CS 442 Mobile Applications
Development (Android Section)

NewsAPI.org Sources Query Results Example:
https://newsapi.org/v2/sources?apiKey=ABC123xyz
The results come in the form of a JSON Object that contains a JSON Array of source entries as shown below. Each entry represents an individual news source (note that the “category” field is referred to as Topic in this application). Example:
{
"status": "ok", "sources": [
{
"id": "abc-news",
"name": "ABC News",
"description": "Your trusted source for breaking news, analysis, exclusive interviews, headlines, and videos at ABCNews.com.",
"url": "https://abcnews.go.com",
"category": "general",
"language": "en",
"country": "us"
}, {
"id": "aftenposten",
"name": "Aftenposten",
"description": "Norges ledende nettavis med alltid oppdaterte nyheter innenfor innenriks, utenriks, sport og kultur.",
"url": "https://www.aftenposten.no",
"category": "general",
"language": "no",
"country": "no"
}, {
"id": "argaam",
"name": "Argaam",
- ارقا م موقع متخصص في متابعة سوق الأسهم السعودي تداول"description": " تاسي - مع تغطيه معمقة لشركات واسعار ومنتجات البتروكيماويات
," تقارير مالية الاكتتابات الجديده ,
"url": "http://www.argaam.com",
"category": "business",
"language": "ar",
"country": "sa"
}, {
. . .
. . .
. . .
}]
}


© Christopher Hield

CS 442 Mobile Applications
Development (Android Section)

NewsAPI.org Articles Query Results Example:
https://newsapi.org/v2/top-headlines?sources=cnn&apiKey= ABC123xyz
The results come in the form of a JSON Object that contains a JSON Array of article entries as shown below. Each entry represents an individual news article. Example:
{
"status": "ok",
"totalResults": 10,
"articles": [{
"source": {
"id": "cnn",
"name" "CNN"
},
"author": "Kaitlan Collins, CNN",
"title": "Joe Biden: Sen. Joni Ernst just proved our point about Trump - CNN Video",
"description": "Democratic candidate Joe Biden says Sen. Joni Ernst's (R-IA) comments about the impeachment testimony impacting Biden's chances in the state proves the real motivation behind Trump's attack on the former vice president and his son.",
"urlToImage": "https://cdn.cnn.com/cnnnext/dam/assets/200128022738-joe-biden-joniernst-split-super-tease.jpg",
"content": "Chat with us in Facebook Messenger. Find out what's happening in the world as it unfolds."
Note that any of the JSON fields can be skipped or specified as null in the JSON. Skipped or null fields should be removed from the display.
Missing or invalid image links should result in a default image displaying.
}, { . . .
. . .
. . .
}
}]
}
NOTE: This API requires the “User-Agent” request property be provided with your
JsonObjectRequest objects. The value this property is set to does not matter, but it must be set. See the example below (red/bold is new):
JsonObjectRequest jsonObjectRequest =
new JsonObjectRequest(Request.Method.GET, url.toString(), null, listener, error) {
@Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> headers = new HashMap<>(); headers.put("User-Agent", ""); return headers;
}
};


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CS 442 Mobile Applications
Development (Android Section)


B) Application Behavior Diagrams:
1) Startup Topics can be selected using the options menu. The content displayed in this menu is dynamic – based upon the data retrieved



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CS 442 Mobile Applications
Development (Android Section)

2) Selecting a Topic


Note that the content found in the options-menu is not Selecting a Topic will reduce the content of hard-coded. The content comes from the data retrieved the News Sources drawer-list by eliminating from the news sources. those that do not match the specified Topic.

For example, the unique list of all news topics from all sources in this example is business, entertainment, general, health, science, sports, and technology. Those topics are used to populate the “Topics” submenu (with the default “all” also added to the submenu). Note that the unique set of topics changes over time and should NOT be hard-coded.


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CS 442 Mobile Applications
Development (Android Section)

3) Selecting a News Source

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CS 442 Mobile Applications
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4) Swipe Right (or Left) to scroll through articles from the selected new source:

5) Click on article title, image, or text to go to extended article on the news source web site


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CS 442 Mobile Applications
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C) News Source Data Representation
The full news source list should always be stored as-is from the API, unchanged (nothing removed). Another
“current” list of sources should be used to hold the “current” sources to be displayed in the drawer. This “current” list of sources will change based upon the Topic selections (is any). The list of current sources should contain all sources at startup (as no topic has been selected).
When a criteria selection is made (i.e., the “business” topic), the “current” source list should be updated to contain only the sources that have “business” as the topic. This is shown below:
Full List
Current List
Source 1
Source 1
Source 2
Source 2
Source 3
Source 3
Source 4
Source 4

Source 100
Source 48

D) Provided Resources (3 images, 2 JSON files)
Image Error Loading Placeholder No Image (i.e., null)

E) Extra Credit:
2) Up to 20 points of extra credit will be awarded if you save and restore the app state when transitioning between portrait and landscape layouts to ensure a smooth user experience. Without this, the app reverts to the start state upon rotation. If this is done properly, the current topic selection, the current source list (in the drawer), and the displayed articles will be maintained upon device orientation change.
3) Up to 25 points of extra credit will be awarded if you display the news topics in the options menu different colors, and then color the news sources in the drawer according to their topic:





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CS 442 Mobile Applications
Development (Android Section)


Assignment Assistance


Submissions & Grading
1) Submissions must consist of your zipped project folder (please execute Build =>Clean Project before generating the zip file).
2) Submissions should reflect the concepts and practices we cover in class, and the requirements specified in this document.
4) Grading will be based upon the presence and proper functionality of all features and behaviors described in this document. NOTE: All descriptions and images constitute the requirements for this assignment.
5) Grading will be performed with the following SDK details:
o Project Compile & Target SDK Version: 30 o Project Minimum SDK Version: 25

6) Grading will be performed on emulator devices with the following characteristics:
Resolution Details Example Emulators
1080 x 1920 With Playstore Pixel, Pixel 2, Nexus 5, Nexus 5X
1080 x 2220 or 2280 With Playstore Pixel 3a, Pixel 4


If you do not understand anything in this handout, please ask.

Otherwise the assumption is that you understand the content.

Unsure? Ask!



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