CODEWITHSUNDEEP
androidkotlinandroidx
Ajay Kulkarni
Ajay Kulkarni

Reputation: 3039

Unresolved reference. None of the following candidates is applicable because of receiver type mismatch

I'm using androidx navigation architecture along with Kotlin 1.2.71 in Android studio 3.2.1. My fragment code is: 

package com.dell.andnav.fragments

import android.os.Bundle
import android.support.v4.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import androidx.navigation.fragment.findNavController
import com.dell.andnav.R
import kotlinx.android.synthetic.main.fragment_welcome.*


/**
 * A simple [Fragment] subclass.
 * Use the [WelcomeFragment.newInstance] factory method to
 * create an instance of this fragment.
 *
 */
class WelcomeFragment : Fragment() {

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_welcome, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        detailButton.setOnClickListener {
            findNavController().navigate(R.id.action_welcomeFragment_to_detailsFragment)
        }
    }

    companion object {
        @JvmStatic
        fun newInstance() = WelcomeFragment()
    }
}

And layout code is: 

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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/frameLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".fragments.WelcomeFragment">


    <Button
        android:id="@+id/detailButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/to_detail_fragment"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

My build.gradle is: 

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'androidx.navigation.safeargs'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.dell.andnav"
        minSdkVersion 21
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        androidExtensions {
            experimental = true
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    def nav_version = "1.0.0-alpha07"
    implementation fileTree(dir: 'libs', include: ['*.jar'])
//    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
//    implementation 'com.android.support:support-v4:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

    implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'androidx.multidex:multidex:2.0.0'
    implementation 'androidx.appcompat:appcompat:1.0.2'

    implementation "android.arch.navigation:navigation-fragment-ktx:$nav_version"
    implementation "android.arch.navigation:navigation-ui-ktx:$nav_version"

    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}
repositories {
    mavenCentral()
}

When I try to run my code, I get below error:

Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: public val Activity.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome public val Dialog.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome public val android.app.Fragment.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome public val androidx.fragment.app.Fragment.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome public val LayoutContainer.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome

How can I resolve that error?

Upvotes: 26

Views: 79912

Answers (6)

Roel Leal
Roel Leal

Reputation: 659

I know, maybe it's not the answer you want hear but I had implements duplicated, just let one and did works for me

Upvotes: 0

CoolMind
CoolMind

Reputation: 28793

I have two issues with this error.

  1. I mixed receiver type in extension.

    import android.widget.Toolbar

fun Toolbar.setMenuItem() : Boolean {
    ...
}

Then tried to apply this function to Toolbar in a layout. But in XML it was androidx.appcompat.widget.Toolbar.

  1. This function led to the error:

    private fun showProgress(view: View? = null) {
    (view?.progressBar ?: progressBar)?.visibility = View.VISIBLE
}

Android Studio offered layouts that contained progressBar, and I chose one. But view?.progressBar continued to be red. Then I shortened a header:

private fun showProgress(view: View).

Only after that AS offered layouts. Then I again wrote: private fun showProgress(view: View? = null).

Upvotes: 0

Rahul Sharma
Rahul Sharma

Reputation: 6169

I have faced the same problem with my adapter class and finally problem solved by adding the following code to build.gradle(Module: app) file of the project.

apply plugin: 'org.jetbrains.kotlin.android.extensions'
androidExtensions {
    experimental = true
}

Since this new version of Kotlin, the Android Extensions have incorporated some new interesting features like caches in any class

Upvotes: 4

Keshav
Keshav

Reputation: 3273

With androidx, you have to access with itemView

itemView.detailButton

import .view.* like below

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

instead of 

import kotlinx.android.synthetic.main.fragment_welcome.*

Upvotes: 0

Debanjan
Debanjan

Reputation: 2836

I had this issue and figured out that the root cause was play-services with versions 17.x.x

My fix

Change

google_android_gms_version

in

implementation "com.google.android.gms:play-services-location:$google_android_gms_version"
    implementation "com.google.android.gms:play-services-gcm:$google_android_gms_version"

from 17.x.x to 15.0.1 The reason is that play services 17.x.x has dependencies on Androidx

General way Click the Gradle option in the extreme right panel, Go to app -> help ->dependencies Search androidx in the chart. Find out which library has it. Change or modify your gradle accordingly.

Those who can migrate to androidx, that well and good. If you have to keep it at appcompat, then follow the answer.

Upvotes: 3

karan
karan

Reputation: 8853

Button you are accessing is inside your fragement but your are accessing it directly. You should access it via parent view like we do with java rootview.findViewById() so use 

view.detailButton.setOnClickListener {
    findNavController().navigate(R.id.action_welcomeFragment_to_detailsFragment)
}

Upvotes: 6

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