Android - How to achieve setOnClickListener in Kotlin?

Question

I wanted to know that how we set basic onClickListener in Kotlin for Android Development.

Answer 1

There are six ways to use SetOnClickListener:

First:

button.setOnClickListener {
    // Do some work here
}

Second:

button.setOnClickListener(object : View.OnClickListener {
    override fun onClick(view: View?) {
        // Do some work here
    }

})

Third:

button.setOnClickListener(View.OnClickListener { view ->
    // Do some work here
})

Fourth:

class MainActivity : AppCompatActivity(), View.OnClickListener{
   
    lateinit var button : Button
            
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        button = findViewById(R.id.button1)
        button.setOnClickListener(this)
    }
        
    override fun onClick(view: View?) {
        when(view?.id){
            R.id.button1->{
                // do some work here
            }
        }
    }
}

Fifth:

class MainActivity : AppCompatActivity(){

    lateinit var button : Button

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        button = findViewById(R.id.button1)
        button.setOnClickListener(listener)
    }
    
    val listener= View.OnClickListener { view ->
        when (view.getId()) {
            R.id.button1 -> {
                // Do some work here
            }
        }
    }
}

Sixth

button.setOnClickListener { view ->         
    // Do some work here 
}

Answer 2

Suppose you have textView to click

text_view.text = "Hello Kotlin";

text_view.setOnClickListener {
    val intent = Intent(this@MainActivity, SecondActivity::class.java)
    intent.putExtra("key", "Kotlin")
    startActivity(intent)
}

Answer 3

Use below code

val textview = findViewById<TextView>(R.id.textview)
textview.setOnClickListener(clickListener)

val button = findViewById<Button>(R.id.button)
button.setOnClickListener(clickListener)

clickListener code.

val clickListener = View.OnClickListener {view ->

    when (view.getId()) {
        R.id.textview -> firstFun()
        R.id.button -> secondFun()
    }
}

Answer 4

Here is an example on how to use the onClickListener in Kotlin

button1.setOnClickListener(object : View.OnClickListener{
            override fun onClick(v: View?) {
                //Your code here
            }})

Answer 5

Method 1:

txtNext.setOnClickListener {
        //Code statements
    }

Method 2:

class FirstActivity : AppCompatActivity(), View.OnClickListener {

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_first)
    txtNext.setOnClickListener(this)
}

override fun onClick(v: View) {
    when (v.id) {
        R.id.txtNext -> {
            //Code statements
        }
        else -> {
            // else condition
        }
    }
  }
}

Answer 6

For using multiple ids:

textview1.setOnClickListener(clickListener)
textview2.setOnClickListener(clickListener)

Create anonymous class:

 private val clickListener: View.OnClickListener = View.OnClickListener { view ->
    when (view.id) {
        R.id.textview1-> { 
           Toast.makeText(this, "Clicked 1", Toast.LENGTH_SHORT).show()
        }
        R.id.textview2-> { 
           Toast.makeText(this, "Clicked 2", Toast.LENGTH_SHORT).show()
        }
    }
}

Answer 7

First you have to get the reference to the View (say Button, TextView, etc.) and set an OnClickListener to the reference using setOnClickListener() method

// get reference to button
val btn_click_me = findViewById(R.id.btn_click_me) as Button
// set on-click listener
btn_click_me.setOnClickListener {
    Toast.makeText(this@MainActivity, "You clicked me.", Toast.LENGTH_SHORT).show()
}

Refer Kotlin SetOnClickListener Example for complete Kotlin Android Example where a button is present in an activity and OnclickListener is applied to the button. When you click on the button, the code inside SetOnClickListener block is executed.

Update

Now you can reference the button directly with its id by including the following import statement in Class file. Documentation.

import kotlinx.android.synthetic.main.activity_main.*

and then for the button

btn_click_me.setOnClickListener {
    // statements to run when button is clicked
}

Refer Android Studio Tutorial.

Answer 8

Use this code to add onClickListener in Kotlin

val button : Button = getView()?.findViewById<Button>(R.id.testButton) as Button
button.setOnClickListener {view ->
         Toast.makeText(context, "Write your message here", Toast.LENGTH_LONG).show()
    }
}

Answer 9

I see a lot of suggestions here, but this collection is missing the following.

button.setOnClickListener(::onButtonClicked)

and in the current class we have a method like this:

private fun onButtonClicked(view: View) {
     // do stuff
}

Answer 10

Simply you can get OnClickListener in kotlin

view1.setOnClickListener{

//body 

}

Answer 11

var tv = findViewById(R.id.tv) as TextView

    tv.setOnClickListener {
       val i = Intent(this@MainActivity, SecondActivity::class.java)
       startActivity(i)
       finish()
    }

Answer 12

A simple way would be to register a click listener and create a click listener with a lambda expression.

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    // click listener registered
    myButton.setOnClickListener(clickListener)
}

And implement the clickListener:

private val clickListener: View.OnClickListener = View.OnClickListener { _ ->
    // do something here
}

You can replace _ with a name if you need the view to use it. For example, you need to check the id of click listener.

private val clickListener: View.OnClickListener = View.OnClickListener { view ->
    if(view.id == login.id) {
        // do something here
    }
}

Answer 13

    val button = findViewById<Button>(R.id.button)
    button.setOnClickListener {
        val intent = 
    Intent(this@MainActivity,ThirdActivity::class.java)
        intent.putExtra("key", "Kotlin")
        startActivity(intent)
    }

Answer 14

**i have use kotlin-extension so i can access directly by button id:**


btnSignIN.setOnClickListener {
            if (AppUtils.isNetworkAvailable(activity as BaseActivity)) {
                if (checkValidation()) {

                    hitApiLogin()
                }
            }
        }

Answer 15

There are several different ways to achieve this, as shown by the variety of answers on this question.

To actually assign the listener to the view, you use the same methods as you would in Java:

button.setOnClickListener()

However, Kotlin makes it easy to assign a lambda as a listener:

button.onSetClickListener {
    // Listener code
}

Alternatively, if you want to use this listener for multiple views, consider a lambda expression (a lambda assigned to a variable/value for reference):

val buttonClickListener = View.OnClickListener { view ->
    // Listener code
}

button.setOnClickListener(buttonClickListener)
another_button.setOnClickListener(buttonClickListener)

Answer 16

Simply do as below :

button.setOnClickListener{doSomething()}

Answer 17

findViewById<Button>(R.id.signUp)?.setOnClickListener(
    Toast.makeText(mActivity, "Button Clicked", Toast.LENGTH_LONG).show()
)

Answer 18

   button.setOnClickListener {
          //write your code here
   }

Answer 19

Button OnClickListener implementation from function in android using kotlin.

Very First Create Button View From .xml File

             `<Button
                android:id="@+id/btn2"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:text="Button2"
                android:layout_weight="0.5"/>`

//and create button instance in Activity

 private var btn1:Button?=null

or

//For Late Initialization can Follow like this,

private lateinit var btn1:Button

//in onCreate,

 btn1=findViewById(R.id.btn1) as Button

     btn1?.setOnClickListener { btn1Click() }

//implementing button OnClick event from Function,

 private fun btn1Click() {
        Toast.makeText(this, "button1", Toast.LENGTH_LONG).show()
    }

Answer 20

You can use view.setOnClickListener{ // your task to execute }

Kotlin type inference and automatic lambda expression will handle the boilerplate. Note: Here view can be anything like TextView or button etc.

Answer 21

You use like that onclickListener in kotlin

val fab = findViewById(R.id.fab) as FloatingActionButton
fab.setOnClickListener {  
...
}

Answer 22

First find the button, to prevent the cast from the View you can use the <> as follows :

val button = findViewById<Button>(R.id.button);

Once you have an instance of the Button, you can now attach the click listener as follows :

button.setOnClickListener {  
 // You code here
}

Answer 23

Here's the solution. Your code will like this:

button.setOnClickListener {
            //your code here
        }

No need to add anything. like below:

val button = findViewById<Button>(R.id.Button)
button.setOnClickListener {

}

Answer 24

val saveButton:Button = findViewById(R.id.button_save)

saveButton.setOnClickListener{
// write code for click event
}

with view object
saveButton.setOnClickListener{
view -> // write code for click event
}

Answer 25

The easiest way that I know to achieve that is through Kotlin Android Extensions.

On your app/build.gradle

apply plugin: 'kotlin-android-extensions'

If your button is called 'btnAdd', then on your fragment or activity import the following:

import kotlinx.android.synthetic.main.fragment_transactions.btnAdd

 override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)

    btnAdd.setOnClickListener {
        Toast.makeText(context , "Done", 10).show()
    }
}

Answer 26

If you want to simulate the old anonymous way in Kotlin I found this worked perfectly.

 btnNewWay!!.setOnClickListener(object:View.OnClickListener {
    override fun onClick(v: View?) {
        //Your Code Here!
    }})

Answer 27

Add clickListener on button like this

    btUpdate.setOnClickListener(onclickListener)

add this code in your activity

 val onclickListener: View.OnClickListener = View.OnClickListener { view ->
        when (view.id) {
            R.id.btUpdate -> updateData()


        }
    }

Answer 28

You can use setOnClickListener like this in Kotlin

button.setOnClickListener(View.OnClickListener {        
       //code
})

Answer 29

Add in build.gradle module file

android {
    ...
    buildFeatures {
        viewBinding true
    }
}

For Activity add

private lateinit var binding: ResultProfileBinding
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = ResultProfileBinding.inflate(layoutInflater)
    val view = binding.root
    setContentView(view)
}

Add on click

binding.button.setOnClickListener { Log.d("TAG", "Example") }

Answer 30

In case anyone else wants to achieve this while using binding. If the id of your view is button_save then this code can be written, taking advantage of the kotlin apply syntax

binding.apply {
    button_save.setOnClickListener {
        //dosomething
    }
}

Take note binding is the name of the binding instance created for an xml file . Full code is below if you are writing the code in fragment. Activity works similarly

private lateinit var binding: FragmentProfileBinding

override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    // Inflate the layout for this fragment
    binding = FragmentProfileBinding.inflate(inflater, container, false)
 
    return binding.root
}

// onActivityCreated is deprecated in fragment
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    binding.apply {
    button_save.setOnClickListener {
        //dosomething
    }
}

Answer 31

Best for achieve click listener in Kotlin(Mean Without findview by id you can click or intalize the textview, button, spinner etc)

Step: -

1. Go to your Build/gradle
2. Add this line : - id 'kotlin-android-extensions'
3. Then Sync the project.

This is Gradle File plugins { id 'com.android.application' id 'kotlin-android' id 'kotlin-android-extensions' }

android { compileSdkVersion 30 buildToolsVersion "30.0.3"

defaultConfig {
    applicationId "com.safal.myapp"
    minSdkVersion 21
    targetSdkVersion 30
    versionCode 1
    versionName "1.0"

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}
compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}
kotlinOptions {
    jvmTarget = '1.8'
}

}

Answer 32

There are multiple ways to do it, I would prefer kotlin way of doing it and minimise the boilerplate code.

Say you have a Button defined in your layout file like this,

<Button
    android:id="@+id/clickMe"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Ok"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

and you want to add onClickListener to this button clickMe You would need below to do this,

1. Add kotlin extension to your existing plugins in build.gradle file like below and sync

        plugins {
           id 'kotlin-android-extensions'
       }
   

2. Add the listener like this,

       clickMe.setOnClickListener {
               Toast.makeText(this@MainActivity, "You clicked me!", Toast.LENGTH_SHORT).show()
           }