In this tutorial we introduce CheckBox, how to use it in android. Our programming language is Kotlin and our IDE is android studio.

Kotlin android checkbox
1. build.gradle
In our app level build.gradle we make sure we have the Kotlin plugin in our dependencies closure.
implementation"org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
2. activity_main.xml
We add our CheckBox as well as our header label TextView here.
It is plain old XML for user interfaces even with Kotlin.
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="info.camposha.kotlincheckboxes.MainActivity"> <TextView android:id="@+id/headerLabel" android:layout_width="wrap_content" android:layout_height="wrap_content" android:fontFamily="casual" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:text="Mr. CheckBox" android:textAllCaps="true" android:textSize="24sp" android:textStyle="bold" /> <CheckBox android:id="@+id/myCheckbox" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" android:text="CheckBox Unchecked" android:padding="5dp" /> </RelativeLayout>
3. MainActivity.java
Here’s our MainActivity.kt kotlin code.
package info.camposha.kotlincheckboxes
import android.app.Activity
import android.os.Bundle
import android.widget.CheckBox
import android.widget.CompoundButton
class MainActivity : Activity() {
/*
when activity is created
*/
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
//reference checkbox
val myCheckBox = findViewById<CheckBox>(R.id.myCheckbox)
//register event handler
myCheckBox.setOnCheckedChangeListener(CompoundButton.OnCheckedChangeListener {
compoundButton, b -> myCheckBox.setText(if (compoundButton.isChecked) "CheckBox Checked" else "CheckBox Unchecked") })
}
}
That’s it.