“android:elevation=” doesn't work on devices pre-Lollipop with compile API21

问题:

I'm trying to use "android: elevation =" in my application but once I run it does not appear in the device with android 4.1.2

gradle

apply plugin: 'com.android.application'  android {     compileSdkVersion 21     buildToolsVersion "21.1.2"      defaultConfig {         applicationId "com.example.alvaro.proyectocaronte"         minSdkVersion 14         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'])     compile 'com.android.support:appcompat-v7:21.0.3' } 

layout.xml

maybe I'm not compiling correctly Lollipop for pre-lollipop devices, Any suggestions?

If you need to see other parts of the code, I'll edit the question

Thanks

回答1:

Elevation requires the device to run Lollipop. See this answer on how to simulate elevation https://stackoverflow.com/a/26747592/680249

回答2:

UPDATED ::

1. Best Practice to do that is

   and add library for cardview

   dependencies {    ...    compile 'com.android.support:cardview-v7:21.0.+'  } 

2. On Pre-Lollipop you can use this drawable

   android:background="@android:drawable/dialog_holo_light_frame"

   it will give you the look of elevation

3. you can create your own like this

reference

回答3:

You can also use a CardView from the support library to implement surfaces.
To do so add a dependency to your build.gradle:

compile 'com.android.support:cardview-v7:23.1.1' 

And then simply use it in your layouts:

Here you have a quite more options to customise it comparing to using @android:drawable/dialog_holo_light_frame as a background

EDIT:
Also notice, that this approach allows you to simply implement
Material Design on Pre-Lolipop devices.
You can change the elevation,
round the corners etc.
To do so you have to:

 app:cardElevation="8dp"  app:cardCornerRadius="8dp"  app:contentPadding="5dp"> 

And not forget to add xmlns:app="http://schemas.android.com/apk/res-auto" to the root layout.

Also you can easily change the elevation in your code:

CardView card = (CardView) findViewById(R.id.yourPreetyCoolCardView); card.setCardElevation(getResources()     .getDimension(R.dimen.card_picked_up_elevation)); 

Use 8dp for picked up and 2dp for resting (usual) state and you will be awesome.

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