Android Kotlin cannot change a text string within a function

Question

I have some really simple Kotlin code for changing a text string within a function generated from a button press, but it does not work. I have a single button and two text strings, one the button press the first text string changes but the text string within the function does not change.

I am sure the problem is with the function call and not passing the right information about the activity, but just cannot work out what is wrong.

MainActivty.kt

package com.example.sandpit9

import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.android.synthetic.main.activity_main.view.*
import org.w3c.dom.Text

class MainActivity : AppCompatActivity() {

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

        imageButton1.setOnClickListener {v: View -> toast(v) }

        imageButton1.setOnClickListener {
            imageButton1.setImageResource(R.drawable.greenbutton)
            textView1.text = "1234"
        }
    }

    public fun toast(v: View) {
        v.textView2.text = "1234"
    }
}

MainActivty.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

<TextView
        android:text="TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textView1"
        android:layout_marginTop="8dp"
        app:layout_constraintTop_toBottomOf="@+id/imageButton1"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        app:layout_constraintStart_toStartOf="parent"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:textSize="34sp"/>
<TextView
        android:text="textvar1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textView2"
        android:textSize="34sp"
        android:layout_marginTop="108dp"
        app:layout_constraintTop_toBottomOf="@+id/imageButton1"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        app:layout_constraintStart_toStartOf="parent"
        android:layout_marginLeft="8dp"
        app:layout_constraintHorizontal_bias="0.535"/>
<ImageButton
        android:layout_width="174dp"
        android:layout_height="154dp"
        app:srcCompat="@drawable/download"
        android:id="@+id/imageButton1"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        app:layout_constraintStart_toStartOf="parent"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintHorizontal_bias="0.542"
        app:layout_constraintVertical_bias="0.187"/>

</android.support.constraint.ConstraintLayout>

RBusarow · Accepted Answer · 2019-04-10 02:20:12Z

2

You're overwriting the click listener. The OnClickListener is a single property - not a list.

imageButton1.setOnClickListener {v: View -> 
  toast(v)
  imageButton1.setImageResource(R.drawable.greenbutton)
  textView1.text = "1234"
}

answered Apr 10, 2019 at 2:20

RBusarow

7647 silver badges12 bronze badges

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Comments

Son Truong · Accepted Answer · 2019-04-10 02:49:51Z

imageButton1.setOnClickListener {v: View -> toast(v) }

imageButton1.setOnClickListener {
    imageButton1.setImageResource(R.drawable.greenbutton)
    textView1.text = "1234"
}

Problem: ImageButton have only one OnClickListener to listen the event when there is a click event on it own. You can set the listener by using setOnClickListener. Because in your code, you use setOnClickListener two times, so the second one will override the first one.

Solution: Change your code to

class MainActivity : AppCompatActivity() {

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

        imageButton1.setOnClickListener {
            imageButton1.setImageResource(R.drawable.greenbutton)
            textView1.text = "1234"
            textView2.text = "1234"
        }
    }
}

Brendon Shaw · Accepted Answer · 2019-04-10 05:24:54Z

Many thanks, how simple is the solution many thanks for all the help, the setOnClickListener is setup only once to trigger the function. This is the finial code that works

package com.example.sandpit9

import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.android.synthetic.main.activity_main.view.*
import org.w3c.dom.Text

class MainActivity : AppCompatActivity() {

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

    imageButton1.setOnClickListener{v: View -> toast(v)}

    }



private fun toast(v: View) {
    imageButton1.setImageResource(R.drawable.greenbutton)
    textView1.text = "1234"
    textView2.text = "1234"



}

}

Happy Singh · Accepted Answer · 2019-04-09 21:47:14Z

-2

remove this import

import kotlinx.android.synthetic.main.activity_main.view.*

Hope this will work

answered Apr 9, 2019 at 21:47

Happy Singh

1,48213 silver badges23 bronze badges

3 Comments

theThapa Over a year ago

@GiorgosNeokleous Removing the import will not fix the issue. But it is still worth noting that importing anything with .* is not suggested.

Giorgos Neokleous Over a year ago

@theThapa Thanks for pointing out. I know that's not recommended. Personally I am not a big fan of kotlin synthetics. However, if that was the answer, there should be a reason explaining why.

theThapa Over a year ago

@GiorgosNeokleous I agree with you. If removing that import is the answer, it would be good to get some explanation.

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