Java Parameters (pt-pt)
RegExTool – The Android App in town
RegExTool
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Wrap Class – Refactor Legacy Pattern
Wrap Class
When using a wrap method, we want to add a new behavior that can be added around the method, such as before or after the existing code.
However, there are times when we need to add behavior in more than one method, like logging before or after some, or all public methods.
Description and how to apply
There are at least 2 ways of doing it:
1. Using the Decorator Pattern
When using the **Decorator Pattern**, we want to make sure both classes implement the same interface or inherit from the same base class, because we want the subclass to have the same “public” interface. This is because a Decorator class can be used interchangeably between the other Decorators. For instance, having a logging decorator or a performance decorator should be as easy as just pass one instance or the other in a class constructor, and its use should be transparent.
2. Aggregating the current class
If you think you want to be more specific about the class being refactored,
then a Wrap Class just wrapping the existing one should be enough. In this case, you don’t need to *extract interface* since the class is passed in the constructor parameters and used in the method. In this approach, you can do a “method rename”, for instance, if the original method was called *process*, the new exposed method could be *processWithLogging*. Another advantage is that in the constructor, you can pass other information useful for the new behavior, something that in the Decorator Pattern can “violate” the Decorator Pattern principle.
Which one?
From the examples below you can observe the Aggregating solution is more specific than the Decorator. Both will work, but if you need help choosing, choose the Decorator if you think that other changes will happen in the future that can be added creating more Decorators, and/or the updates are just adding new behavior, and probably you expect changes in multiple methods, like logging every public method. Use the Aggregating solution if the change is very specific, just in a few places and you don’t expect great changes in the future for these methods.
Examples
Imagine the following business existing code:
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// // Existing code // public interface PaymentProcessor { void pay(); } public class CustomerPaymentProcessor implements PaymentProcessor { public void pay() { System.out.println("Pay it forward!"); } } |
Using the Decorator Pattern
You just have to replace the calls to CustomerPaymentProcessor with the Decorator, sice both implement the same interface.
Probably when refactoring you will need to *Extract Interface* or create an *Abstract Class* to implement this pattern.
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// // Now the decorator (from the code is easy to observe how easy is to create any decorator) // public class LogPaymentDecorator implements PaymentProcessor { private PaymentProcessor paymentProcessor; public LogPaymentDecorator(PaymentProcessor paymentProcessor) { this.paymentProcessor = paymentProcessor; } public void pay() { System.out.println("You are starting to pay"); paymentProcessor.pay(); System.out.println("Ok, now we are even ;)"); } } |
Using a Wrapper Class
Here, the solution is specific to the code refactoring being done, it cannot be reused.
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// // The Warp Class // - You can observe this solution as more specific to the target class than the Decorator // public class LoggingCustomerPaymentProcessor private CustomerPaymentProcessor customerPaymentProcessor; public LoggingCustomerPaymentProcessor(CustomerPaymentProcessor cpp) { CustomerPaymentProcessor = cpp; } // You can give the name you want to the method public void loggedPayWithStars() { System.out.println("You are starting to pay"); customerPaymentProcessor.pay(); System.out.println("Ok, now we are even ;)"); } } |
Android Adventures – Development Tips – Part 5
How to add the back button on the Activity Action Bar
If the character space stops working with EditBox when using Listeners
Probably it is the google keyboard trying to impose words instead of characters
The one solution that worked for me was to disable the text suggestions
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android:inputType="textMultiLine|textNoSuggestions" |
Android Adventures-Development Tips-Part 4
| How to remove the divider in a ListView? | ||||
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| What if my text doesn’t fit in a TextView? | ||||
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| How to return values from to the caller Activity? | ||||
Main Activity:
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| Highlight an item in a ListView | ||||
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Android Adventures–Development Tips-Parte 3
| How to shrink activity layout when virtual keyboard is displayed and hides some of the views? | ||
| There are several different solutions, one of them is:
– In the AndroidManifest.xml, for the target activity android:windowSoftInputMode=”adjustResize” |
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| If you use Database Room framework for SQLite management and Kotlin: | ||
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| If you are using Kotlin don’t create a new method, you can have compilation errors on the generated class | ||
| java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long period of time. | ||
| Solution 1: add allowMainThreadQueries
MyApp.database = Room.databaseBuilder(this, AppDatabase::class.java, “MyDatabase”).allowMainThreadQueries().build() Solution 2: Use another thread Solution 3: If you use Kotlin 1.3+ you can use coroutines |
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| How to explore a database in Android Emulator? | ||
| – You can copy the db files from the device to your computer and use a sqlite browser
– I use: Android Debug Database: https://github.com/amitshekhariitbhu/Android-Debug-Database |
Android Adventures – Development Tips – Parte 2
| How to add an icon to a button? | ||
| android:drawableLeft=”@android:drawable/ic_menu_search” | ||
| How to push a button in a LinearLayout to the right? | ||
| The trick in is the empty view
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| How to have an ImageButton transparent? | ||
| android:background=”@null” | ||
| How to clear all the Spannable styles in an EditText? | ||
| val currentPositionsInputText = contentTextEditBox.selectionStart contentTextEditBox.setText(contentTextEditBox.text.toString()) |
Android Adventures – Development Tips
| How to prevent an EditBox from expanding?
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| How to add a Scrollbar to an EditBox? |
| android:scrollbars=”vertical” |
| How to write the text on top left of the EditBox? |
| android:gravity=”top|left” |
| How to avoid the overlap of the Toolbar with the included layout? |
| How to Highlight blocks of text in an EditBox? |
| Spannable spannable=new SpannableString(string); // You can add other styles here, like bold, underline, other// if you are using a loop, put the Spannable construction outside the loop or sometimes only the last one will be used spannable.setSpan(new ForegroundColorSpan(Color.BLUE), start, end, 0); |
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