Develop Reference

My app crashes on devices running Android version below 9

I am testing my app in Samsung remote lab and discovering that it keep crashing in devices running on Android below 9.
Searching on Google made me only more confused and aware of how vast is my ignorance.
build.cradle:
android {
compileSdkVersion 28
buildToolsVersion "30.0.3"
defaultConfig {
applicationId "com.photobangkok.moneytalk"
minSdkVersion 16
targetSdkVersion 28
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'androidx.appcompat:appcompat:1.2.0'
implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
implementation 'com.google.android.gms:play-services-ads:20.1.0'
}
When I try to lower minSDKversion to 14 I got the below error:
Manifest merger failed : uses-sdk:minSdkVersion 14...
I am showing ads in this app so I need to use adroidx.

Downgrade Android SDK from 29 to 21

I need to downgrade my SDK to 21 in order to test some deprecated features that are no longer working properly on SDK 29. But when I lower SDK and sync project it gives an error when compiling app.
The error is C:\Users\user\.gradle\caches\transforms-2\files-2.1\93bc303e0edf41378a70a682ebb74605\appcompat-1.1.0\res\values-v26\values-v26.xml:5:5-8:13: AAPT: error: resource android:attr/colorError not found.
Here are my build.gradle settings
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
android {
compileSdkVersion 21
buildToolsVersion '28.0.3'
defaultConfig {
applicationId "com.example.oldstuff"
minSdkVersion 15
targetSdkVersion 21
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.core:core-ktx:1.2.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.1'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
}
What should be added/removed?

This issue occurs when you use compileSdkVersion and buildToolsVersion less than 26
Your compileSdkVersion is 21, but it can be possible that third party libraries use resources that were only added in API 26 or later. Either update your build.gradle file to use the newest compileSdkVersion or try to downgrade third party libraries.

I can´t execute my app on my phone sdk old, I must change my gradle?

I´m using Android Studio version 3, I´m trying to execute my simple app, but this comes out:
pkg: /data/local/tmp/com.example.jhon.pasardatosentreactivities
Failure [INSTALL_FAILED_OLDER_SDK]
Installation failed since app's minSdkVersion is newer than device's API level (API 1).
Please update your apps minSdkVersion.
Error while Installing APK
I have to de some sort of update on my phone? Or I have to change may gradle?
Note: The code is very short, I don´t think is necessary.
gradle
apply plugin: 'com.android.application'
android {
compileSdkVersion 28
defaultConfig {
applicationId "com.example.jhon.pasardatosentreactivities"
minSdkVersion 27
targetSdkVersion 28
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:28.0.0-rc01'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
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'
}
Please make the answer with detail, I'm new on this.

Change like this:
defaultConfig {
applicationId "com.example.jhon.pasardatosentreactivities"
minSdkVersion 1 //set this equal to your target device's android api level
targetSdkVersion 28
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
But support libraries have smallest API level limitation which greater than 1 , so I suggest you update device OS or buy newer phone.

"Error:(2) Error retrieving parent for item No resource found that matches the given name 'android:TextAppearance.Material.Widget.Button.Inverse'

I have a problem with Gradle !!
It keeps showing me errors , can some one help me to resolve this problem
Note: It's my first time to install android studio

Try using this:
compile 'com.android.support:appcompat-v7:24.1.0'
Use latest support library and change your target and compile sdk also
compileSdkVersion 24
buildToolsVersion "24.0.1"
targetSdkVersion 24

Try it
compile "com.android.support:appcompat-v7:23.0.1"
and you can change targetSdkVersion 23

Please use my project gradle values and also update sdk libraries:
apply plugin: 'com.android.application'
android {
compileSdkVersion 23
buildToolsVersion "23.0.1"
defaultConfig {
multiDexEnabled true
applicationId "com.example.student" //change as your package name
minSdkVersion 16
targetSdkVersion 23
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.0.1'
}

Try to match all versions:
compileSdkVersion 23
buildToolsVersion '23.0.0'
targetSdkVersion 23
Add Following dependencies:
compile 'com.android.support:appcompat-v7:23.0.0'
Make sure you use latest version of Sdk:
how to update sdk

The problem is you're using
compile 'com.android.support:appcompat-v7:19.+'
which gives you all possibilities of Android 4.4.2 Kitkat API 19 and older.
In your project you're trying to use Material Themes which belongs to newer version, I mean com.android.support:appcompat:$version, where version > 21.
Material Design was introduced with Android 5.1 Lollipop API 21
I higly reccomend you to change your build.gradle file to:
apply plugin: 'com.android.application'
android {
compileSdkVersion 24
buildToolsVersion "24.0.2"
defaultConfig {
minSdkVersion 21
targetSdkVersion 21
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile "com.android.support:appcompat-v7:24.2.1"
}
but of course changing appcompat library to version :
com.android.support:appcompat-v7:23.0.1"
would be enough ;-)
Hope it would help

Emulators are not showing in Android Studio

In Android Studio the Emulators are not showing . I tried that disabling ADB Integration. but it is not working for me.
Please give me solution for this problem.

Maybe your project is not compatible (API version) with the target emulator. Check build.gradle file if the targetSDK and minimumSdk version is lower or equal to the sdk version of your Emulator.
Be sure that your compiledSdkVersion matches minSdkVersion and supported by targetSdkVersion. For example:
apply plugin: 'com.android.application'
android {
compileSdkVersion 23
buildToolsVersion "24.0.0"
defaultConfig {
applicationId "zeta.sqlitetest3"
minSdkVersion 16
targetSdkVersion 23
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.4.0'
}