Develop Reference

Trying to Change src of an ImageButton in another layout folder other than activity_main

to sum up I am trying to change the src of ImageButtons inside my dialog_colors.xml file from MainActivity. However whatever I do I couldnt manage to change it. I tried the same code with ImageButtons inside my activity_main.xml but it doesnt work for buttons inside dialog_colors.xml file.
activity_main.xlm
<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">
<include
android:id="#+id/dialog_colors"
layout="#layout/dialog_colors"/> ...
dialog_colors.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical">
<LinearLayout
android:id="#+id/ll_paint_colors"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="horizontal">
<ImageButton
android:id="#+id/red"
android:layout_width="40sp"
android:layout_height="40sp"
android:src="#drawable/pallet_normal"
android:background="#color/Red"
android:layout_margin="1sp"
android:tag="redTag"
android:clickable="true"
android:onClick="selectColor"
/>...
MainActivity.kt
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
colorDialog=findViewById<LinearLayout>(R.id.dialog_colors)
firstRowColors=colorDialog.findViewById<LinearLayout>(R.id.ll_paint_colors)
secondRowColors=colorDialog.findViewById<LinearLayout>(R.id.ll_paint_colors2)
drawingView=findViewById<DrawingView>(R.id.drawingView)
pressedColor=secondRowColors[0] as ImageButton
pressedColor!!.setImageResource(R.drawable.pallet_pressed)
}...
I tried the same thing with TextViews etc too. It seems like I cannot change anything inside the dialog_colors.xml file.
Do not get confused about the firstRows, secondRows etc, there are many ImageButtons, it doesnt work for any of them.

I found a solution to define an attribute in the MainActivity.kt through activity_main.xml to content_main.xml (included layout). The key word here is DataBinding. The project is completely reproducible and I provide first Kotlin and at the very end the JAVA files.
KOTLIN:
To enable DataBinding you need to go to your build.gradle(Module) and add following code:
//...
dataBinding{
enabled true
}
//...
You define a container called DrawableContainer as a Kotlin class. There you define a Drawable called customDrawable.
Thus DrawableContainer.kt:
import android.graphics.drawable.Drawable
data class DrawableContainer(val customDrawable: Drawable)
Now we will define our MainActivity.kt which will bind our chosen Drawable and pass it through our Container (DrawableContainer).
Our MainActivity.kt:
import android.app.Activity
import android.os.Bundle
import androidx.databinding.DataBindingUtil
import com.example.imagebuttonexperiment.databinding.ActivityMainBinding
class MainActivity : Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val binding: ActivityMainBinding = DataBindingUtil.setContentView(
this, R.layout.activity_main)
binding.drawable = DrawableContainer(resources.getDrawable(R.drawable.my_image))
}
}
The missing parts are our XML files. The code below shows our content_main.xml. It contains a variable (in <data>) we will define named drawable. The type guides to our DrawableContainer. So this is the first bridge between our Container and our layout we will <include. In the ImageButton you can see that as android:src we refer over our variable to our Drawable in our Container. That's why android:src="#{drawable.customDrawable}".
Thus content_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<layout
xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable
name="drawable"
type="com.example.imagebuttonexperiment.DrawableContainer" />
</data>
<ImageButton
android:layout_width="match_parent"
android:layout_height="100dp"
android:layout_margin="10dp"
android:src="#{drawable.customDrawable}"/>
</layout>
Now it's important to build our second bridge. Yet, we have DrawableContainer -> content_main. This will be the bridge content_main -> MainActivity. Therefor we have our <data/> and variable defined again. As you can see in <include we bind:drawable the exact same variable which is in both XML files.
The missing piece in our puzzle is the activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<layout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:bind="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
tools:context=".MainActivity">
<data>
<variable
name="drawable"
type="com.example.imagebuttonexperiment.DrawableContainer" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<include
android:id="#+id/include_content"
layout="#layout/content_main"
bind:drawable = "#{drawable}"/>
</LinearLayout>
</layout>
RESULT:
The final result is an ImageButton in the MainActivity that was included by another Layout. But the Drawable was chosen from the MainActivity and passed a Container to be shown in the included Layout. Magic isn't it!? ;)
JAVA:
And I will keep my word and provide you the JAVA version also.
The XML files and gradle will be the same, you only need to use MainActivity.java instead of MainActivity.kt, the same for DrawableContainer.java instead of DrawableContainer.kt.
Here is the same in green, DrawableContainer.java:
import android.graphics.drawable.Drawable;
public class DrawableContainer {
public final Drawable customDrawable;
public DrawableContainer(Drawable customDrawable) {
this.customDrawable = customDrawable;
}
}
And of course our MainActivity.java:
import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;
import android.annotation.SuppressLint;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import com.example.imagebuttonexperiment.databinding.ActivityMainBinding;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActivityMainBinding mainBinding = DataBindingUtil.setContentView(this,R.layout.activity_main);
mainBinding.setDrawable(new DrawableContainer(getDrawable(R.drawable.my_image)));
}
}
DOWNLOAD PROJECT:
In addition I provide the project with both, JAVA and Kotlin classes in it. You just need to comment the content of the 2 classes grey you don't want. In example, if you want to use Kotlin, grey the content of .java files.
Github Project
Documentation & Tutorial:
Databinding Android Documentation
Youtube Tutorial: How to bind data?

NOTE: That's somewhat a solution of my problem:
I have tried this:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
colorDialog2=Dialog(this)
colorDialog2.setContentView(R.layout.dialog_colors)
colorDialog2.setTitle("Colors")
firstRowColors=colorDialog2.findViewById<LinearLayout>(R.id.ll_paint_colors)
secondRowColors=colorDialog2.findViewById<LinearLayout>(R.id.ll_paint_colors2)
drawingView=findViewById<DrawingView>(R.id.drawingView)
pressedColor= secondRowColors[0] as ImageButton
pressedColor!!.setImageResource(R.drawable.pallet_pressed)
}
intead of this in Main.Activity
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
colorDialog=findViewById<LinearLayout>(R.id.dialog_colors)
firstRowColors=colorDialog.findViewById<LinearLayout>(R.id.ll_paint_colors)
secondRowColors=colorDialog.findViewById<LinearLayout>(R.id.ll_paint_colors2)
drawingView=findViewById<DrawingView>(R.id.drawingView)
pressedColor=secondRowColors[0] as ImageButton
pressedColor!!.setImageResource(R.drawable.pallet_pressed)}
And it worked, I managed to change the src however I wanted. (Only did this change didnt do the changes that the others provided) However, I am not even sure if this is a good practice. It works as a quick fix for sure tho.
I will look into DEX7RA's answer more later on.

MainActivity.kt doesn't recognise button by ID

I'm struggling with very common problem, I think.
I've created a button in xml file and tagged it with ID. Then I wanted to make onClickListener in MainActivity.kt. But when I'm typing button's ID, it's marked red and it seems like Android Studio doesn't recognise it. I've tried cleaning and rebuilding project, but the problem still exist. Invalidate Caches/Restart didn't help as well.
Here's XML Code
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:background="#color/backgroundColor"
android:fadingEdge="vertical"
android:fadingEdgeLength="80dp"
android:gravity="center_horizontal"
android:orientation="vertical"
android:padding="16dp"
tools:context=".MainActivity"
tools:viewBindingIgnore="true">
<Button
android:id="#+id/btnDateBicker"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="25dp"
android:backgroundTint="#3D446C"
android:text="Select Date"
android:textSize="25sp"
android:textStyle="bold" />
</LinearLayout>
And here's kotlin code
package com.example.ageinminutes
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val mybtn = findViewById<btnDateBicker>()
}
}

If you simply want to fetch by id, use findViewById method.
val myBtn: Button = findViewById(R.id.btnDateBicker)
or
val myBtn = findViewById<Button>(R.id.btnDateBicker)
Another way to play with views in the kotlin file:
Try with synthetic binding, like just start writing few words of XML id in your kotlin file and android studio will attach that view for you. [Deprecated after Android 11]
Try with view binding or data binding, you just have to enable these settings in build.gradle file. [More Robust way]

Try this:
val mybtn = findViewById<Button>(R.id.btnDateBicker)

Android Studio 'findViewById' no longer working

I am very new to Android/Kotlin. I have already created some programs and am making good progress.
But since today I have the problem that I can't get an 'findViewById' running even in the standard 'Hello World' program (Empty Activity).
I have only added the line android:id="#+id/myText" in the XML.
And in MainActivity.kt the line var myTxt = findViewById(android.R.id.myText).
But I get the error message Unresolved reference: 'myText'
The text 'myText' is red.
The usual attempts: Clear Cache, new project, ... I have already tried. The behavior is always the same.
In older projects 'findViewById' is working fine. But I find no difference in Import or settings between working and non working projects.
All in Android Studio 4.1.1
I am grateful for any help
Jan
<?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/myText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
package com.example.myhelloworld
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
var myTxt = findViewById<TextView>(android.R.id.myText)
}
}

android.R.id.something is only used for android's own internal resources. You should remove that and it will work properly.

In kotlin you dont need to set findViewById instead you can just call the TextView name like this: myText.setText(userNameWithMsg)

android. was the problem! I removed it and all is fine again.
Thank you all! Must be a kind of copy paste error ;-))
Now I can go on .....
Great forum!
Thanks a lot
Jan

Error inflating class com.facebook.drawee.view.SimpleDraweeView

I'm trying to use the fresco library. I used it before too and it was working, but now, for some reason I get:
Unable to start activity ComponentInfo{com.example.home.template/com.example.home.template.MainActivity}: android.view.InflateException: Binary XML file line #26: Error inflating class com.facebook.drawee.view.SimpleDraweeView
My xml file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:fresco="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.facebook.drawee.view.SimpleDraweeView
android:id="#+id/profileImage"
fresco:actualImageScaleType="centerCrop"
android:layout_width="200dp"
android:layout_gravity="center_horizontal"
android:layout_height="200dp" />
</LinearLayout>
MyApplication:
public class MyApplication extends Application {
#Override
public void onCreate() {
super.onCreate();
FacebookSdk.sdkInitialize(this);
}
}
I have it in my manifest: android:name=".MyApplication"
The only problem that I'm having is with the draweeview. I can do all of the other stuff such as logging in and taking information.

In my case writing Fresco.initialize(this); before setContentView(R.layout.myxml); helped me.
Update:
you have FacebookSdk.sdkInitialize(this); instead of Fresco.initialize(this) in your myapplication

I was getting this problem in API 19 devices just because I was using drawable vector as placeholder here
fresco:placeholderImage="#drawable/ic_phone"
After changing to PNG my problem was solved.
Dont forget to initialize it in your App as
class App : Application() {
override fun onCreate() {
super.onCreate()
Fresco.initialize(this)
}
}
as well as this line in manifest's application
android:name=".App"

Today I had the same problem. However, I forgot to add the property android:name=".MyApplication" in the AndroidManifest.xml.

In your Application class write the following line:
Fresco.initialize(this);

Make sure that you import the right Fresco library and if you do import other Fresco libraries, make sure the other libraries version number is the same with Fresco core library

Admob 6.1.0 for monodroid

I have an app made with monodroid, it's on release stage (ready to get released) but I would like to have a free ad-supported version of my app. I've been searching the web for a tutorial of Admob 6.1.0 implementation on monodroid without any luck. I'd have to mention that I've never worked with ads before.
I was wondering if anyone has been able to use Admob 6.1.0 on monodroid and if you could share your knowledge
I've seen this source code and also this tutorial, but I just can't manage to understand correctly how to implement it. I't would be nice if someone could make an answer as a community wiki so it can help others to get introduced to Admob in monodroid
EDIT:
Tried Greg Shackles sample step by step, i'm now getting this error android.view.InflateException: Binary XML file line #1: Error inflating class com.google.ads.AdView. Any sugestion of how to make it work?
EDIT 2:
Changed the XML file and now getting 2 new errors: Java.Lang.NoClassDefFoundError and System.TypeInitializationException. XML looks like this:
<?xml version="1.0" encoding="UTF-8" ?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/Background2"
>
<com.google.ads.AdView android:id="#+id/ad"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
ads:adSize="BANNER"
ads:adUnitId="AD_UNIT_ID_GOES_HERE"
ads:testDevices="TEST_EMULATOR,TEST_DEVICE_ID_GOES_HERE"
ads:loadAdOnCreate="true"/>
</RelativeLayout>
And adview is called like this:
public class MyActivity : Activity
{
private View _adView;
protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
SetContentView(Resource.Layout.AboutActivityLayout);
AdMobHelper.RegisterEmulatorAsTestDevice();
_adView = FindViewById(Resource.Id.Ad);
AdMobHelper.RequestFreshAd(_adView);
loadData();
}
}

The first error you got "android.view.InflateException: Binary XML file line #1: Error inflating class com.google.ads.AdView" is related to the Jar Build Action setting.
You should check two things first:
the jar file has the Build Action property set to "AndroidJavaLibrary"
the java file called "AdMobHelper.java" should have the Build Action property set to "AndroidJavaSource"
It seems to me that the error you are getting now is related to the java file not being correctly configured as an AndroidJavaSource.