AndroidSketchpad

Welcome to this post. In this post, we are going to discuss android text to speech.
Before the start, check the official documentation of Android text to speech.

In my case, I use this option with a fab (Floating action button). When the user clicks on this fab button this text to speech is triggered and user heard the speech.
Let's start,
Implement TextToSpeech.OnIntListener on your activity class.

public class DetailsActivity extends AppCompatActivity implements
        TextToSpeech.OnInitListener {
}

Create an instance of TextToSpeech Class

private TextToSpeech toSpeech;

override onIint() methods and follow below steps:
 1. First, we need to check if Text to speech engine is installed or not

if (status != TextToSpeech.ERROR) {
}

2. If the status is not erroring then we set a default language, we set here the US as default.

int result = toSpeech.setLanguage(Locale.US);

3. now check language data is missing or not supported or not installed then we start for install this text to speech engine.

if (result == TextToSpeech.LANG_MISSING_DATA ||
    result == TextToSpeech.LANG_NOT_SUPPORTED ||
    result == TextToSpeech.ERROR_NOT_INSTALLED_YET) {

      Intent installIntent = new Intent();
      installIntent.setAction(
              TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
      startActivity(installIntent);

}

if you missing something check the full code of onInit() method

@Override
    public void onInit(int status) {

        if (status != TextToSpeech.ERROR) {

            int result = toSpeech.setLanguage(Locale.US);

            if (result == TextToSpeech.LANG_MISSING_DATA ||
                    result == TextToSpeech.LANG_NOT_SUPPORTED ||
                    result == TextToSpeech.ERROR_NOT_INSTALLED_YET) {

                Intent installIntent = new Intent();
                installIntent.setAction(
                        TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
                startActivity(installIntent);

            }

        }
    }

Create a method and add a single parameter, word as String. In my case, I named it as setTTS() and parameter is word as String,
setTTS(String selectedWord)

private void setTTS(String selectedWord) {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            toSpeech.speak(selectedWord, TextToSpeech.QUEUE_FLUSH, null, null);

        } else {
            toSpeech.speak(selectedWord, TextToSpeech.QUEUE_FLUSH, null);
        }

    }

Note: below methods is deprecated. So check if the device is lollipop and higher then use utterance as an extra parameter.

One more thing to go.
We need to shut down this TextToSpeech engine when the activity is destroyed. but before we need to check textToSpeech is null or not to avoid any error. If it is not null the call stop and shutdown method. see the code

@Override
protected void onDestroy() {
   super.onDestroy();
   if (toSpeech != null) {
       toSpeech.stop();
       toSpeech.shutdown();
    }
}

That's it 
you finished writing coding. Now call setTTS() method from anywhere in your project. You can use it as Button onClick or TextView onClick. Just pass a string parameter and call the method. As I told you, at the beginning of this post I am using this option in a fab button. you can that code by the following link. But don't be confused. This is the full activity code, so there is a lot of things with TextToSpeech. Click GitHub link.

Now you can use this code. Hope you understand this TextToSpeech logic. and you will be you use this option in your next or existing project.

Thanks for reading this post.
Happy coding.

welcome to firebase series.

In this post, we are going to learn about how to connect firebase from the android studio. This is the easiest methods ever.
we can directly connect firebase through the android studio.
Let's start-
open any project or create the new project
I am going throw picture by picture. Follow picture to picture for completing this process.

In android studio click tool and select firebase.
after click that it will open this window

implementation 'com.google.firebase:firebase-auth:11.2.0'

Now create an instance of FirebaseAuth class
see the code-

val mAuth = FirebaseAuth.getInstance()

use signInAnonymously() method and add a complete listener. if the task is successful we show a message that Authentication is successful and also user id. if failed then we will show a fail message.

mAuth.signInAnonymously()
     .addOnCompleteListener(this, { task ->
         if (task.isSuccessful) {
                val user = mAuth.currentUser
                Toast.makeText(this, "Authentication successful. user id ${user.uid}",
                                Toast.LENGTH_SHORT).show()

            } else {
                // If the sign in fails displays a message to the user.
                Toast.makeText(this, "Authentication failed.",
                                Toast.LENGTH_SHORT).show()

                    }
                })

That's it coding see the final screen short in the firebase console

Welcome to kotlin Series

In this post, we are going to discuss a very important topic of Kotlin. The topic is kotlin null safety.
I think you already heard this keyword, null safety, Kotlin is a null safety language. right?
what is the null safety? In kotlin by default, you can not assign a value of a variable as null. All the variable must have a value.

but if you want an assign a variable as null, you have to use?
code-

val nullValue:String? = null

if you want to create a variable but want to assign a value later then use

var name:String?
name = "shudipto"

now print the value

println("Name: $name")

output:

Name: shudipto

now assign this value to null

name = null

print this new value

println(name)

Output:

null

Note: if you want to set this variable must have value then use below code-

print(name!!)

now we create a function that returns null

//null return function
fun returnNull():String? {
    return null
}

print this value:

 println("Function: ${returnNull()}")

Output:

 println("Function: ${returnNull()}")

now we use the force operator to assign the return value of this methods

val returnNull1:String ?= returnNull()

now if we want to learn the length of this variable we can use length method

//val returnNull2 = returnNull1.length

but this line shows an error because the value of the variable is null. This is the advantage of kotlin. If you are in java the here this line program will be crashed. but in kotlin, we can do by this way without any crash

val returnNull2 = returnNull1?.length

Now, this program will not crash. but you can do another thing that is if the value is null then you can save a string or default value I am using a string

val returnNull2 = returnNull1?.length ?: "value is null"

print the value

println("ReturnNull2: $returnNull2")

output:

ReturnNull2: value is null

see the variable value is null so the default value is assigned. you can also use this method for the specific data type variable:

val returnNull4:String = returnNull() ?: "No name"

print the value:

println(returnNull4)

Output:

No name

That's it. Hope you understand the concept. This is very important in Android App development. It prevent some unexpected crash.

Thank you very much.
Happy coding

welcome to kotlin series.

Kotlin Series

In this series, we are basically going through some basic and advanced tutorial about kotlin language.
we try to serve you best practices on those tutorials.

Here is the collection of all post

1. String -  kotlin string tutorial
2. Array and loop - array and loop tutorial
3. File reader and write - kotlin IO tutorial. 
4. ArrayList - kotlin ArrayList
5. How to control loop in kotlin - kotlin loop control
6. Collection - kotlin collection such as hash map, array, list
7.Null Safety - kotlin null safety

Series tutorial:
Kotlin OOP series:

1. OOP Basic
2. Constructor
3. Inheritance
4. Method Overriding

Advance:
1.Bookstore a simple program with function and input-output from the console with conditions. 

Welcome to kotlin Series

In the tutorial, we are going to discuss Kotlin collection.
we touch on below topics
1. Hashmap
2. Array
3. List
       3.a. mutable list
       3.b. immutable list
4. Set
       4.a. mutable set
       4.b. immutable set

Let's start-

Hashmap: In kotlin, we can use java hashmap easily. But kotlin has an own hashmap. First, we go through Java hashmap create an instance of Hashmap class and parameter will be string and string after input some data and print data to check.
see the code-

val hasMap = HashMap<String,String>()

hasMap.put("s","Shudipto")
hasMap["d"] = "trafder"
hasMap["f"] = "Himu"
hasMap["g"] = "Rupa"

now print a value

println(hasMap["s"])

Output:

Shudipto

I am using a for loop to print all the value that stored in hashmap with their key. code-

for ((v,k) in hasMap.entries){
        println("$v -> $k")
    }

Output:

s -> Shudipto
d -> trafder
f -> Himu
g -> Rupa

that's it in this way we use java hashmap. But kotlin has already a default hashmap. now use kotlin hashmap.
See the code

val hasmap = hashMapOf(1 to "shudipto")
hasmap.put(2,"trafder")
hasmap.put(3,"himu")

print a value

println(hasmap[1])

Output:

shudipto

use a for loop to see all the value with the key that stored in the hashmap.

//print all value with index
for ((position,value) in hasmap.entries){
    println("Index:$position value:$value")
}

Output:

//print all value with index
for ((position,value) in hasmap.entries){
    println("Index:$position value:$value")
}

That's all on hashmap. next topics Array

Array: kotlin has a special array class. let's see the example. But before jump into code, you can check our two tutorial about ArrayList and Array and loop. This will help you to understand the array concept easily.
see the code-

println("\nKotlin Array")
val array = arrayOf("Shudipto",1,2,3.5,"Trafder")
array[4] = "himu"

now print all the value with for loop-

for ((p,v) in array.withIndex()){
    println("Index:$p value:$v")
}

Output:

Index:0 value:Shudipto
Index:1 value:1
Index:2 value:2
Index:3 value:3.5
Index:4 value:himu

That's it on Array. Next topics is  list

List:  In kotlin, there are two types of list available. Mutable and immutable list.
see the code-
mutable list-

println("\n\nMutable list of array")
val list = mutableListOf(1,2,34,5,6,7,8,"Shudipto")

list[0] = "trafder"

immutable list-

val list2 = listOf(1,2,34,5,6,7,8,"Shudipto")

Mutable vs immutable list: you can not update immutable list after assign.

now print all the value by using for loop
mutable list-

for ((p,v) in list.withIndex()){
    println("Index:$p value:$v")
}

Output:

Mutable list of array
Index:0 value:trafder
Index:1 value:2
Index:2 value:34
Index:3 value:5
Index:4 value:6
Index:5 value:7
Index:6 value:8
Index:7 value:Shudipto

Immutable List

println("\n\nimmutable list of array")
for ((p,v) in list2.withIndex()){
    println("Index:$p value:$v")
}

Output:

immutable list of array
Index:0 value:1
Index:1 value:2
Index:2 value:34
Index:3 value:5
Index:4 value:6
Index:5 value:7
Index:6 value:8
Index:7 value:Shudipto

That's it on the list. Nest on set.

Set: As list, kotlin has also two types of set. one is mutable and second is immutable.
so see the code
mutable set-

val mSet = mutableSetOf(1,2,4,5,6,6,8,1)
mSet.add(5)

immutable set

val set = setOf(15,2,3,10,5,6,15,10)

mutable vs immutable set: you can update mutable set anytime. But immutable set can not update after assign.
print all the value
mutable set-

for ((p,v) in mSet.withIndex()) println("Index:$p value:$v")

output:

Index:0 value:1
Index:1 value:2
Index:2 value:4
Index:3 value:5
Index:4 value:6
Index:5 value:8

Immutable set-

for ((p,v) in set.withIndex()) println("Index:$p value:$v")

Output:

Index:0 value:15
Index:1 value:2
Index:2 value:3
Index:3 value:10
Index:4 value:5
Index:5 value:6

That's it on set.

oh! we finish all the topics. Before finish this post I will give you a gift topics.
List vs set:
you probably see that list and set is working basically same process. List and Set both save a collection of data. They also have the mutable and immutable option. you can save any time of data type and you can also mix data type. but the question is, what is the difference between list and set?
the answer is, the set is not stored duplicate value but list save. If you are working with duplicate value then you must use list. or, If you are want to ignore duplicate value then use set.

Thank you for reading.
Hope you enjoy this tutorial.
Happy coding.

Welcome to kotlin Series

In this small post, we are going to discuss how to control loop in Kotlin.
Basically, we use 2 keywords for the control loop.
1. continue
2. break
if we want to skip one process, then we use to continue the keyword

for (a in 1..5){
        if (a==4){
            continue
        }
        println("A: $a")
    }

Output:

A: 1
A: 2
A: 3
A: 5

or if we stop the loop then we use break keyword

for (a in 1..5){
    if (a==4){
        break
     }
    println("A: $a")
}

Output:

A: 1
A: 2
A: 3

But in the nested loop if we want to stop the second loop after a selected value.
But in this case, if we use break keyword in the second loop-

for (a in 1..5){
        println("A: $a")

        for (b in 1..5){
            if (a == 4){
                break
            }
            println("B: $b")
        }
    }

and output:

A: 1
B: 1
B: 2
B: 3
B: 4
B: 5
A: 2
B: 1
B: 2
B: 3
B: 4
B: 5
A: 3
B: 1
B: 2
B: 3
B: 4
B: 5
A: 4
A: 5
B: 1
B: 2
B: 3
B: 4
B: 5

so we see loop is not stopped. It only stops inner loop after reaching the value of a is 4. no value of this loop is not printed and it repeated every time with increasing value with a
But our target on the basis of above value, we want to stop whole loop not only second loop after the value of a is 4.
For this case, we use loop keyword.
See the code-

loop@ for (a in 1..5){
        
        println("value a:$a")

        for (b in 1..4){
            if (a == 4){
                break@loop
            }

            println(" b:$b")
        }
    }

    println("Loop done")

Output:

value a:1
 b:1
 b:2
 b:3
 b:4
value a:2
 b:1
 b:2
 b:3
 b:4
value a:3
 b:1
 b:2
 b:3
 b:4
value a:4
Loop done

Oh! now our loop is stopped when the value of a is 4
sometimes we need to control the inner loop with the main loop condition. So loop keyword is saved a lot of time, we don't need to implement the complex logic.

Thank you for reading this post.
Happy coding