How to write HelloWorld program in kotlin-Chapter-3

In the previous blog, I wrote about val and var use and their differences. In this post, I am going to introduce you to the basic steps to write a program in Android with Kotlin. Just follow simple steps below:-

1)First, declare a string type variable. You can either use val or var for initializing your variable and keep in mind that if you are reinitializing a variable do not use val. write a simple line :-

var str=”Hello World” or

var str: String=”Hello World” or

val str=”Hello World” or

val str: String=”Hello World”

2)In second step, you have to add the textView element in activity_main.xml like below and give a unique id

<TextView
android:id=”@+id/textView”
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
app:layout_constraintBottom_toBottomOf=”parent”
app:layout_constraintLeft_toLeftOf=”parent”
app:layout_constraintRight_toRightOf=”parent”
app:layout_constraintTop_toTopOf=”parent” />

3)In the MainActivity.kt. we will initialize a textview using findViewById method like below:-

var textview=findViewById(R.id.textView) as TextView

4)In the last, you have to assign string value inside textview using text function.

textview.text=str

5)You are done. Now just run your program. Below is a full code snippet for you to see.

package adapter.manasvi.com.simpleproject

import android.os.Bundle
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class HelloWorld : AppCompatActivity() {
    val str:String="Hello World"
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        var textview=findViewById(R.id.textView) as TextView
        textview.text=str
    }
}