RegExTool – The Android App i...

RegExTool A new Android App was deployed to the Android Play Store. This application is very useful for developers or people from operations wh...

Wrap Class – Refactor Legacy ...

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. How...

Android Adventures – Developm...

How to add the back button on the Activity Action Bar [kotlin] // in the OnCreate.... supportActionBar!!.setDisplayHomeAsUpEnabled(true) // an...

Android Adventures-Development Tips...

How to remove the divider in a ListView? [crayon-5cbd7a4b1c024989503701/] What if my text doesn’t fit in a TextView? [cra...

RegExTool – The Android App in town

Jan. 04 Others no comments

RegExTool

A new Android App was deployed to the Android Play Store.

This application is very useful for developers or people from operations who need to use regular expressions. Just try it!

Write and visualize the matchs in real time!

Wrap Class – Refactor Legacy Pattern

Jan. 04 Architecture & Developing, Projects no comments

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:

//
// Existing code
//
public interface PaymentProcessor {
    void pay();
}

public class CustomerPaymentProcessor implements PaymentProcessor {

    public void pay() {
        System.out.println("Pay it forward!");
    }

}

// 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.

//
// 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 ;)");

    }

}

// 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.

//
// 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 ;)");
    }
}

// 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

Jan. 02 Architecture & Developing no comments

How to add the back button on the Activity Action Bar

// in the OnCreate....
supportActionBar!!.setDisplayHomeAsUpEnabled(true)

// and override
override fun onSupportNavigateUp(): Boolean {
finish()
return true
}

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

android:inputType="textMultiLine|textNoSuggestions"

1	android:inputType="textMultiLine\|textNoSuggestions"

Android Adventures-Development Tips-Part 4

Dec. 28 Apps and Tools no comments

How to remove the divider in a ListView?

android:divider="@null"

1	android:divider="@null"

What if my text doesn’t fit in a TextView?

android:ellipsize="marquee" -– it will scroll horizontally
android:ellipsize="end" – it will display “…”

1 2	android:ellipsize="marquee" -– it will scroll horizontally android:ellipsize="end" – it will display “…”

How to return values from to the caller Activity?

Main Activity:

{
    val intent = Intent(this, SecondActivity::class.java)
    intent.putExtra("someparametertosendkey", true)

    // call the activity like this
    startActivityForResult(intent, "akeytoidentifytheresult")
}

// This method is called when the second activity finishes
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
    super.onActivityResult(requestCode, resultCode, data)

// Check that it is the SecondActivity with an OK result
    if (requestCode != USE_REGEX_RESULT_KEY) return

   if (resultCode == Activity.RESULT_OK) {

    // Get String data from Intent
    someview1.setText(data.getStringExtra("aresultfromsecondactivity1"))
    someview2.setText(data.getStringExtra("aresultfromsecondactivity2"))
    }
}
...
//
// Second Activity:
//

    // return the result
    val intent = Intent()
    intent.putExtra("aresultfromsecondactivity1", selectedItem.expression)
    intent.putExtra("aresultfromsecondactivity2", selectedItem.example)
    setResult(Activity.RESULT_OK, intent)
    finish()

{

val intent = Intent(this, SecondActivity::class.java)

intent.putExtra("someparametertosendkey", true)

// call the activity like this

startActivityForResult(intent, "akeytoidentifytheresult")

}

// This method is called when the second activity finishes

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {

super.onActivityResult(requestCode, resultCode, data)

// Check that it is the SecondActivity with an OK result

if (requestCode != USE_REGEX_RESULT_KEY) return

if (resultCode == Activity.RESULT_OK) {

// Get String data from Intent

someview1.setText(data.getStringExtra("aresultfromsecondactivity1"))

someview2.setText(data.getStringExtra("aresultfromsecondactivity2"))

}

...

// Second Activity:

// return the result

val intent = Intent()

intent.putExtra("aresultfromsecondactivity1", selectedItem.expression)

intent.putExtra("aresultfromsecondactivity2", selectedItem.example)

setResult(Activity.RESULT_OK, intent)

finish()

Highlight an item in a ListView

&lt;ListView
         android:id="@+id/regExListView"
         android:layout_width="match_parent"
         android:choiceMode="singleChoice" // choose 1 item only
         android:dividerHeight="3dp" // the space between items
         android:layout_height="wrap_content"&gt;

<ListView

android:id="@+id/regExListView"

android:layout_width="match_parent"

android:choiceMode="singleChoice" // choose 1 item only

android:dividerHeight="3dp" // the space between items

android:layout_height="wrap_content">

// and in the code if you want to only change the background
for (a in 0 until parent.childCount) {
    val item = parent.getChildAt(a)
    item.setBackgroundColor(Color.TRANSPARENT)
}

view.setBackgroundColor(resources.getColor(R.color.colorPrimaryUltraLight))

// and in the code if you want to only change the background

for (a in 0 until parent.childCount) {

val item = parent.getChildAt(a)

item.setBackgroundColor(Color.TRANSPARENT)

}

view.setBackgroundColor(resources.getColor(R.color.colorPrimaryUltraLight))

Android Adventures–Development Tips-Parte 3

Dec. 28 Architecture & Developing no comments

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”

If you use Database Room framework for SQLite management and Kotlin:

plugins {
id "org.jetbrains.kotlin.kapt" version "1.3.11"
}

buildscript {
  repositories {
    maven {
      url "<a href="https://plugins.gradle.org/m2/">https://plugins.gradle.org/m2/"</a>
    }
  }

  dependencies {
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.11"
  }
}

apply plugin: "org.jetbrains.kotlin.kapt"
kapt "android.arch.lifecycle:compiler:1.1.1"
// instead of
annotationProcessor "..."

plugins {

id "org.jetbrains.kotlin.kapt" version "1.3.11"

}

buildscript {

repositories {

maven {

url "<a href="https://plugins.gradle.org/m2/">https://plugins.gradle.org/m2/"</a>

}

dependencies {

classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.11"

}

apply plugin: "org.jetbrains.kotlin.kapt"

kapt "android.arch.lifecycle:compiler:1.1.1"

// instead of

annotationProcessor "..."

If you are using Kotlin don’t create a new method, you can have compilation errors on the generated class

@Insert
fun new(vararg regexs: RegEx)
// use
@Insert
fun save(vararg regexs: RegEx)

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

private fun saveSomething(e: Entity) = runBlocking {

  val job = GlobalScope.launch {
    database.myDao().save(e)
  }
  job.join()

Toast.makeText(applicationContext,"Saved",Toast.LENGTH_LONG).show()
finish()
}

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

Dec. 26 Architecture & Developing no comments

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

<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="0.05"
android:orientation="horizontal">
<TextView android:text="@string/RegExTitle"
android:textColor="@color/colorPrimaryDark"
android:gravity="center_vertical|start"
android:layout_marginStart="7dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<View
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="1"/>
<Button
android:gravity="center_vertical|end"
android:layout_marginEnd="7dp"
android:drawableLeft="@android:drawable/ic_menu_delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</LinearLayout>

<LinearLayout

android:layout_width="match_parent"

android:layout_height="0dp"

android:layout_weight="0.05"

android:orientation="horizontal">

<TextView android:text="@string/RegExTitle"

android:textColor="@color/colorPrimaryDark"

android:gravity="center_vertical|start"

android:layout_marginStart="7dp"

android:layout_width="wrap_content"

android:layout_height="wrap_content"/>

<View

android:layout_width="0dp"

android:layout_height="0dp"

android:layout_weight="1"/>

<Button

android:gravity="center_vertical|end"

android:layout_marginEnd="7dp"

android:drawableLeft="@android:drawable/ic_menu_delete"

android:layout_width="wrap_content"

android:layout_height="wrap_content">

</LinearLayout>

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

Dec. 25 Apps and Tools, Architecture & Developing no comments

How to prevent an EditBox from expanding?

android:layout_width="0dp" – or height, depending the need and the use of the weight

android:layout_weight="1" – if you just have one and you want to fill the whole layout

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);
editText.setText(spannable);

Android App – Just Send It 1.0

Dec. 24 Apps and Tools, Architecture & Developing, Projects no comments

I just developed an Android application to improve your productivity.
Just Send It, an Android application to send a note with the fewer clicks possible.

An application developed to just Write and Send to your preferred email account.

Enjoy it!

Give Me Numbers 1.1

Dec. 24 Apps and Tools, Architecture & Developing no comments

I released an update to my first Android application developed Give Me Numbers.

User Interface Improved, more colorful
You can choose a separator for the numbers generated

Scrum Master Certification PSM I from scrum.org – checked!

Sep. 04 Managing no comments

After being a PMP certified the next challenge was for sure the Scrum Master certification. A different challenge but it deserved a try.
After reading several books, training hundreds of questions… the effort brought its results.
Soon I will detail here the books I read a and still do, for the certification.

1 2 … 10 →

José da Cruz

@it.blog