Developing an Android library

Slides from my barcamp talk at Droidcon Vienna 2016.

Transcript

1. Developing an Android library DINO KOVAČ
2. 01 WHY?
3. WHY A LIBRARY? • DRY - don’t repeat yourself • easier than copy/pasting classes
4. WHY AN OPEN SOURCE LIBRARY? • saving others time • useful contributions from community • eternal fame!
5. 02 WHAT?
6. DOES IT MAKES SENSE TO BUILD IT? • is there a real need? • any existing libraries?
7. PICK A GOOD NAME • one that doesn’t already exist • should make sense • bonus points if it’s amusing • example: • HTTParty - Makes http fun again!
8. 03 HOW?
9. MIND THE API • primary way users interact with your lib • make it easy to use • make it robust (avoid footguns!)
11. HTTPURLCONNECTION HttpURLConnection urlConnection = null;
 try {
 URL url = new URL("https://api.github.com/markdown/raw");
 connection = (HttpURLConnection) url.openConnection();
 connection.setDoOutput(true);
 connection.setChunkedStreamingMode(0);
 
 OutputStream out = new BufferedOutputStream(connection.getOutputStream());
 writeStream(out);
 
 InputStream in = new BufferedInputStream(connection.getInputStream());
 readStream(in);
 } catch (IOException e) {
 // handle this
 } finally {
 if (connection != null) {
 connection.disconnect();
 }
 }
12. HTTPURLCONNECTION
13. OKHTTP Request request = new Request.Builder()
 .url("https://api.github.com/markdown/raw")
 .post(RequestBody.create(MediaType.parse("text/plain"), "post body"))
 .build();
 
 try {
 Response response = client.newCall(request).execute();
 } catch (IOException e) {
 // handle this
 }
14. FAIL FAST • as much validation as reasonably possible • fail as fast as possible
15. FAIL FAST public Builder post(RequestBody body) {
 return method("POST", body);
 }
 
 public Builder method(String method, RequestBody body) {
 if (method == null || method.length() == 0) {
 throw new IllegalArgumentException("method == null || method.length() == 0");
 }
 if (body != null && !HttpMethod.permitsRequestBody(method)) {
 throw new IllegalArgumentException("method " + method + " must not have a request body.");
 }
 if (body == null && HttpMethod.requiresRequestBody(method)) {
 throw new IllegalArgumentException("method " + method + " must have a request body.");
 }
 this.method = method;
 this.body = body;
 return this;
 }
16. DON’T EXPOSE THE INTERNALS • package-protected classes • private or protected methods
17. APP RESOURCES LIBRARY RESOURCES MERGED RESOURCES
18. APP RESOURCES LIBRARY RESOURCES MERGED RESOURCES @string/app_name @string/app_name @string/app_name
19. APP RESOURCES LIBRARY RESOURCES MERGED RESOURCES @string/app_name (en) @string/app_name (fr) @string/app_name (de) @string/app_name (en) @string/app_name (fr) @string/app_name (de) @string/app_name
20. ANDROID SPECIFICS • build.gradle • resourcePrefix 'dbinspector_'
21. WRITE THE DOCS • what does it do? • how do I use it? • maybe an example app?
22. DISTRIBUTE • don’t use maven central, use jcenter • automate deployment
23. SHAMELESS SELF-PROMOTION • https://github.com/infinum/android_dbinspector • https://github.com/reisub/HttPizza
24. Any questions? DINO@INFINUM.CO @DINO_BLACKSMITH Visit infinum.co or find us on social networks: infinum.co infinumco infinumco infinum