Retrolambda+bolts
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This document discusses using Bolts and RetroLambda to refactor asynchronous code in Android. It describes how Bolts can be used to serialize asynchronous tasks and callbacks into single tasks. RetroLambda allows using Java 8 lambda expressions in older versions of Java. The document provides an example of refactoring asynchronous dialog code using Bolts and RetroLambda to simplify callbacks into a single continueWith call.
Retrolambda+bolts
- 2. • Bolts-Android • Design API Based On Bolts • Retrolabmda • Refactor
- 3. Why use ? • spec.
- 4. member func() { Serialize Asynchronous Tasks callback { callback { callback{ } then { then { then { } } } } member func() { } } }
- 5. • Bolts-Android • Design API Based On Bolts • Retrolabmda • Refactor
- 6. Example show dialog press “YES” button Cancel Do something NO YES
- 7. Example 1/4 public class RunnableCB implements Runnable { public void run() { this.run(); } }
- 8. private AlertDialog simpleAlertDialog(String message, final RunnableCB cb) { if (cb == null) { final RunnableCB emptyCallback= new RunnableCB() { public void run() { } }; return buildDialog(message, "OK", emptyCallback); } else { return buildDialog(message, "OK", cb); } } Example 2/4
- 9. private AlertDialog buildDialog(String message, String cb1Option, final RunnableCB cb1) { AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setMessage(message); builder.setPositiveButton(cb1Option, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); cb1.run(); } }); return builder.create(); } Example 3/4
- 10. final RunnableCB cbSwitchOff = new RunnableCB() { public void run() { ((CompoundButton) bleSwitch).setChecked(false); } }; String str = getResources().getString(R.string.no_ble_device_available); simpleAlertDialog(str, cbSwitchOff).show(); Example 4/4
- 11. Refactor with Bolts public class Dialog { static Task<Integer> dlg(String msg, String opt1, String opt2) { final Task<Integer>.TaskCompletionSource tcs = Task.create(); AlertDialog.Builder builder = new AlertDialog.Builder(mContext); builder.setMessage(msg); if (opt1 != null && !opt1.isEmpty()) { builder.setPositiveButton(opt1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { tcs.setResult(0); } }); } if (opt2 != null && !opt2.isEmpty()) { builder.setPositiveButton(opt2, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { tcs.setResult(1); } }); } AlertDialog d = builder.create(); d.show(); return tcs.getTask(); } }
- 12. String str = getResources().getString(R.string.no_ble_device_available); mDialog.show(str, "OK", null).continueWith(new Continuation<Integer, Void>() { @Override public Void then(Task<Integer> task) throws Exception { ((CompoundButton) bleSwitch).setChecked(false); return null; } }); Calling API we made RunnableCB
- 13. , they !! ( Java)
- 14. • Bolts-Android • Design API Based On Bolts • Retrolabmda • Refactor
- 15. What’s Retrolambda • Back port Java8 to Java 7, 6, 5 • Syntax Sugar ( ) • Good introduction : Ingram Chen http:// ingramchen.io/blog/2014/10/retromlambda.html
- 16. Retrolambda Limitation • Does not back port Java 8 APIs https://docs.oracle.com/javase/8/docs/api/java/ util/function/package-summary.html
- 18. // defined in the SDK interface OnClickListener { public void onClick(View v); } // your code mButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // do something here } }); syntax sugar 1/2
- 19. mButton.setOnClickListener((View v) -> { // do something here }); syntax sugar 2/2
- 20. • Bolts-Android • Design API Based On Bolts • Code Example • Retrolabmda • Refactor
- 21. public class Dialog { static Task<Integer> dlg(String msg, String opt1, String opt2) { final Task<Integer>.TaskCompletionSource tcs = Task.create(); AlertDialog.Builder builder = new AlertDialog.Builder(mContext); builder.setMessage(msg); if (opt1 != null && !opt1.isEmpty()) { builder.setPositiveButton(opt1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { tcs.setResult(0); } }); } if (opt2 != null && !opt2.isEmpty()) { builder.setPositiveButton(opt2, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { tcs.setResult(1); } }); } AlertDialog d = builder.create(); d.show(); return tcs.getTask(); } } -> ->
- 22. String str = getResources().getString(R.string.no_ble_device_available); mDialog.show(str, "OK", null).continueWith(new Continuation<Integer, Void>() { @Override public Void then(Task<Integer> task) throws Exception { ((CompoundButton) bleSwitch).setChecked(false); return null; } }); ->
- 23. public Task<Integer> show(String msg, String opt1, String opt2) { final Task.TaskCompletionSource tcs = Task.create(); final AlertDialog.Builder builder = new AlertDialog.Builder(mContext); builder.setMessage(msg); if (opt1 != null && !opt1.isEmpty()) { builder.setPositiveButton(opt1, (DialogInterface dialog, int which) -> { tcs.setResult(0); }); } if (opt2 != null && !opt2.isEmpty()) { builder.setNegativeButton(opt2, (DialogInterface dialog, int which) -> { tcs.setResult(1); }); } AlertDialog d = builder.create(); d.show(); return tcs.getTask(); } Result 1/2
- 24. mDialog.show1(R.string.no_ble_device_available).continueWith(task -> { ((CompoundButton) bleSwitch).setChecked(false); gotoScanPage(); return null; }); Result 2/2