class MainActivity : AppCompatActivity() {

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

    fun buTestUpdateText2 (view: View) {
        val changePage = Intent(this, Page2)
        // Error: "Please specify constructor invocation;
        // classifier 'Page2' does not have a companion object"

        startActivity(changePage)
    }

}

public Intent(Context packageContext, Class<?> cls)

Intent(this, Page2::class.java)

val intent = Intent(this, NextActivity::class.java)
// To pass any data to next activity
intent.putExtra("keyIdentifier", value)
// start your next activity
startActivity(intent)

val intent = Intent(this, SecondActivity::class.java)
intent.putExtra("key", value)
startActivity(intent)

startActivity(Intent(this@CurrentClassName,RequiredClassName::class.java)

class MainActivity : AppCompatActivity() {

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

    fun buTestUpdateText2 (view: View) {
        startActivity(Intent(this@MainActivity,ClassName::class.java))

        // Also like this

        val intent = Intent(this@MainActivity,ClassName::class.java)
        startActivity(intent)
    }

val intent = Intent(this, Page2::class.java)
startActivity(intent)

val changePage = Intent(this, Page2::class.java)

startActivity(Intent(this, Page2::class.java).apply {
    putExtra("extra_1", value1)
    putExtra("extra_2", value2)
    putExtra("extra_3", value3)
})

class MainActivity : AppCompatActivity() {
val userName = null
val password = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button.setOnClickListener {
    val intent = Intent(this@MainActivity,SecondActivity::class.java);
    var userName = username.text.toString()
    var password = password_field.text.toString()
    intent.putExtra("Username", userName)
    intent.putExtra("Password", password)
    startActivity(intent);
 }
}

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_second)
var strUser: String = intent.getStringExtra("Username")
var strPassword: String = intent.getStringExtra("Password")
user_name.setText("Seelan")
passwor_print.setText("Seelan")
}