I can't see the elements by their id in Android Studio

user_14042930 0
Viewed 3023

I'm a new Kotlin Programmer. I tried to change the app icon by deleting the ic_launcher.png files and replacing my own images. As i see that is ridiculous what i'm trying to do, i copied the "Main Activity.kt" and "main_activity.xml" files and created a new project. As i tried to copy the files into the new project, the program throws a lot of errors:

The Main Activity

It didn't imported the "kotlinx" packet and didn't perceive the elements in the xml file. As i tried to create an another new project to try whether the problem is only for this project, i realized that Android Studio doesn't perceive the xml elements anymore.

It doesn't see the UI elements

Here are some important infos about my project:

The Android Manifest XML File

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.ihdovanay.myapplication">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.MyApplication">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

The Build Gradle File of The Project

buildscript {
    ext.kotlin_version = "1.4.10"
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:4.1.0"
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

The Build Gradle File of the Module

plugins {
    id 'com.android.application'
    id 'kotlin-android'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.2"

    defaultConfig {
        applicationId "com.ihdovanay.myapplication"
        minSdkVersion 21
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}

dependencies {

    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.3.2'
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.2.1'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.2'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
}

I would be very happy if you could solve my problem.

kotlin-android-extensions kotlin android-studio android
2 Answers

Revised answer after the deprecation of view synthetics.

You're missing the kotlin-android-extensions plugin in your build.gradle. It's responsible for generating synthetic view references.

kotlin-android-extensions is now deprecated, so it is no longer included by default and should no longer be added to projects. You should use findViewById or View Binding.

You can make it work by doing the following, but I don't recommend adding and relying on a deprecated library. Add the line to your plugins block at the top:

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}
user_5067960

In Android Studio 4.1.1, the following code is missing in build.gradle (module: yourAppName)

id 'kotlin-android-extensions'
user_136547440
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