MainActivity.kt
package com.example.jetpack
import android.content.Context
import android.os.Bundle
import android.util.TypedValue
import androidx.appcompat.app.AppCompatActivity
import androidx.constraintlayout.widget.ConstraintLayout
import androidx.core.view.*
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Set text view margins
val params = textView.layoutParams as ConstraintLayout.LayoutParams
params.setMargins(8.toDp(this))
textView.layoutParams = params
button.setOnClickListener {
// Update text view end/right margin
params.updateMarginsRelative(end = 75.toDp(this))
textView.layoutParams = params
}
button2.setOnClickListener {
// Update text view different margins
params.updateMarginsRelative(
50.toDp(this),
40.toDp(this),
30.toDp(this),
20.toDp(this)
)
textView.layoutParams = params
}
}
}
// Extension method to convert pixels to dp
fun Int.toDp(context:Context):Int = TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_DIP,this.toFloat(),context.resources.displayMetrics
).toInt()
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
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=".MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="#CCFF00"
android:gravity="center"
android:text="Hello Android"
android:padding="16dp"
android:textAppearance="@style/TextAppearance.AppCompat.Large"
android:textSize="35sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:backgroundTint="#E52B50"
android:text="Update End Margin"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:backgroundTint="#333399"
android:text="Update margins"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.501"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/button" />
</androidx.constraintlayout.widget.ConstraintLayout>
build.gradle dependencies[add]
// android ktx
implementation 'androidx.core:core-ktx:1.2.0'
build.gradle [add]
android {
kotlinOptions {
jvmTarget = JavaVersion.VERSION_1_8.toString()
}
}



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