MainActivity.kt
package com.example.jetpack
import android.content.Context
import android.graphics.Color
import android.os.Bundle
import android.util.TypedValue
import android.view.Gravity
import android.view.View
import android.view.ViewGroup
import android.widget.ArrayAdapter
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// mutable list of plants to populate grid view
val list = mutableListOf(
"Catalina ironwood",
"Cabinet cherry",
"Pale corydalis",
"Pink corydalis",
"Belle Isle cress",
"Orange coneflower",
"Coast polypody",
"Water fern"
)
// set the grid view item height in dp and convert it to pixels
val itemHeight = 90.dpToPixels(this)
// array adapter for grid view
val adapter = object : ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,list) {
override fun getView(
position: Int, convertView: View?,
parent: ViewGroup
): View {
return (super.getView(position, convertView, parent) as TextView)
.apply {
text = list[position]
gravity = Gravity.CENTER
// grid view vertical spacing, horizontal spacing and
// item background color together make border between items
setBackgroundColor(Color.parseColor("#7DF9FF"))
// set grid view item height in pixels
layoutParams.height = itemHeight
}
}
}
gridView.adapter = adapter
// set grid view item click listener
gridView.setOnItemClickListener { adapterView, view, i, l ->
// get grid view clicked item text
val selectedItem = adapterView.getItemAtPosition(i).toString()
textView.text = selectedItem
}
}
}
// extension function to convert dp to equivalent pixels
fun Int.dpToPixels(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:id="@+id/constraintLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:background="#F0FFFF">
<GridView
android:id="@+id/gridView"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:background="#8BA8B7"
android:horizontalSpacing="3dp"
android:numColumns="2"
android:verticalSpacing="3dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:textColor="#004F98"
android:textSize="30sp"
android:fontFamily="sans-serif-condensed-medium"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/gridView"
tools:text="TextView" />
</androidx.constraintlayout.widget.ConstraintLayout>

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