Basically, it works like a stack where each view is stacked on top of the other

Create a drawable file for shadow view and assign name as image_shadow and add code in this file.

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<corners
android:radius="10dp"
/>
<gradient
android:angle="270"
android:centerX="300%"
android:startColor="#00000000"
android:endColor="#99000000"
android:type="linear"
/>
<size
android:width="270dp"
android:height="60dp"
/>
<stroke
android:width="1dp"
android:color="#878787"
/>
</shape>

Now, xml file and add the below code into it and set this drawable file as view background

<androidx.appcompat.widget.LinearLayoutCompat
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".MainActivity">

<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">

<androidx.appcompat.widget.AppCompatImageView
android:id="@+id/imageView"
android:layout_width="250dp"
android:layout_height="250dp"
android:scaleType="centerCrop"
android:src="@drawable/shopping_image"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>

<View android:id="@+id/view"
android:layout_width="250dp"
android:layout_height="250dp"
android:background="@drawable/image_shadow"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>

<androidx.appcompat.widget.AppCompatTextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:textColor="@android:color/white"
android:text="Write your text here"
android:textSize="25sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="@+id/view"/>

</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.appcompat.widget.LinearLayoutCompat>

we learning in this blog run your app without connecting a USB cable.The main purpose of this blog user-run app without any restriction.Some time connect cable with device and device disturbing and the app not run properly issues

Step 1:

Notes:

• the third image in an already installed plugin in my android studio so friend your android studio in install this plugin.
• then your android studio restart - this point flow.

• your android studio again start then forth image in showing "ADB Wifi" option showing 

• click ADB Wifi and below image showing one look open in your android studio 
• a simple click to connect 
• before click to connect remember your device and pc in connect same wifi otherwise not connect the device 
• android studio open first time one time connect your device with USB then not needed

dependencies {
    implementation "com.google.android.material:$latest_version"
}

Snackbar.make(view, "Show some message here", Snackbar.LENGTH_SHORT).show()

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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/coordinatorLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.application.snackbarapp.MainActivity">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <Button
            android:id="@+id/button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_centerVertical="true"
            android:text="show snackbar" />

    </RelativeLayout>

</android.support.design.widget.CoordinatorLayout>

import android.graphics.Color;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private CoordinatorLayout coordinatorLayout;
    private Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        coordinatorLayout = findViewById(R.id.coordinatorLayout);
        button = findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showSnackbar();
            }
        });
    }

    public void showSnackbar() {
        Snackbar snackbar = Snackbar.make(coordinatorLayout, "Marked as Read", Snackbar.LENGTH_INDEFINITE)
                .setAction("UNDO", new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Snackbar snackbar1 = Snackbar.make(coordinatorLayout, "Undo successful", Snackbar.LENGTH_SHORT);
                        snackbar1.show();
                    }
                })
                .setActionTextColor(Color.RED);

        snackbar.show();
    }
}

• Debug APK is very fast in building and Release APK is a little bit slow.

How to create Release APK File:

• Flowing below all steps 
• Open android studio
• Click Build on the toolbar
• Click Generate Signed Bundle/APK.

  

•  Select APK 
• Click the Next button

  

• After clicking the next button, you will see the following dialog.
• Click the "Create new..." button, highlighted in the following image by a red circle if you are creating an APK for the first time. Otherwise, you can choose from existing.

  

• It will open one another dialog box
• Key store path in select save location .jks file 
• Fill in all the information
• Set a valid name for key alias
• Set 100 as validity years
• Fill Certificate Information
• Click OK

• After you click on it, select "release" from the dialog box 
• Select "V1 (Jar Signature)" & "V2 (Full APK Signature)" checkboxes
• Click Finish
• It will start the process of building your APK

How to create a debug .apk file

• Click Build and select Build Bundles(s)/APK(s) 
• select "Build APK(s)" from the dialog box 
• It will start the process of building your debug APK file creating 

Search Keys :

• Shift+Shift — Search Every Where
• Ctrl+F — Find Text within a Single File
• Ctrl+Shift+F-Find Text in All Files
• Ctrl+R — Replace Selected Text in a Single File
• Ctrl+Shift+R — Replace Selected Text in all Files (Be Careful while Using This)
• Ctrl+Shift+A —Search for IDE Commands

• Ctrl+N — Navigate to Class
• Ctrl+Shift+N — Navigate to a File
• Ctrl+B — Jump to Declarations
• Alt+ ↑ — Jump to the Previous Method
• Alt+↓ — Jump to Next Method
• Ctrl+G — Jump to Line
• Ctrl+E — Recent Files
• Ctrl+Shift+Back Space — Jump to Last Edited Location
• Ctrl+B — Find Declarations
• Ctrl+Left Mouse(or)Ctrl+Alt+F7— Show Usage
• Alt + F7 / Ctrl + F7 — Find usages /Find usages in file
• Ctrl+Shift+B — Find Implementations
• F3 — Find Next
• Shift+F3 — Find Previous

• F11 — Toggle bookmark
• Ctrl+F11 — Toggle bookmark with the mnemonic(0–9 or A-Z)
• Ctrl +(0–9) — Go to numbered bookmark
• Shift+F11 — Show all Bookmarks
• Ctrl + Shift + F7 — Highlight usages in file

• Ctrl + W — Extend selection (selects a word->line->method->Class )
• Ctrl +Shift+ W — Decrease Selection
• Alt + J — Select next occurrence
• Ctrl + Alt + Shift + J — Select all occurrences
• Alt + Shift + J — Unselect occurrence
• Ctrl+Shift+V — Paste from recent buffers (from a History of Copied Contents)

• Ctrl+F6  — Refractor Code
• Ctrl+D — Duplicate a Line/Selected part
• Ctrl+Y — Delete a Line/Selected part
• Ctrl+Q — Quick Documentation
• Ctrl + Space — Code completion
• Ctrl+Shift+Space — Smart code completion (by expected type removes unrelated suggestions)
• Alt+Insert — Generate Code
• Ctrl+J — Insert Live template
• Ctrl + O — Override methods
• Ctrl + I — Implement methods
• Ctrl + Alt + T — Surround with…
• Ctrl + / — Comment / uncomment with line comment
• Ctrl + Shift + / — Comment / uncomment with block comment
• Ctrl+Alt+L — Reformat code

• Ctrl + F9 — Compile and Run Make a project
• Ctrl + Shift + F9 — Compile selected file, package or module
• Shift + F10 — Run
• Shift + F9 — Debug
• Ctrl + Shift + F10 — Run context configuration from editor

• F8 / F7 — Step over / into
• Shift + F7 / Shift + F8 — Smart step into/Step out
• Alt + F9 — Run to cursor
• Alt + F8 — Evaluate expression
• F9 — Resume program
• Ctrl + F8 — Toggle break point
• Ctrl + Shift + F8 — View breakpoints

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:drawable="@color/white" />
    
    <item
        android:drawable="@drawable/ic_icon_vector"
        android:gravity="center" />

</layer-list>

<!-- Splash Screen theme. -->
<style name="SplashTheme" parent="Theme.AppCompat.NoActionBar">
    <item name="android:windowBackground">@drawable/splash_background</item>
</style>

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

    <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">
        
        <activity
            android:name=".SplashActivity"
            android:theme="@style/SplashTheme">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

public class SplashActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        startActivity(new Intent(SplashActivity.this, MainActivity.class));
        finish();
    }
}

• 1.Open android studio
• 2.Go to drawable 
• 3.right click drawable menu
•  flow below image steps:

• -Creating a capsule shape flow below code:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >

  <corners
    android:bottomLeftRadius="30dp"
    android:bottomRightRadius="30dp"
    android:radius="60dp"
    android:topLeftRadius="30dp"
    android:topRightRadius="30dp" />

  <solid android:color="#CFCFCF" />

  <padding
    android:bottom="0dp"
    android:left="0dp"
    android:right="0dp"
    android:top="0dp" />

  <size
    android:height="60dp"
    android:width="270dp" />
 
</shape>

• The below image is showing the shape corner radius

• -Solid means shape inner color “#CFCFCF”

•  Its very simple shape width - height 

dependencies {
    implementation ‘androidx.cardview:cardview:1.0.0’
}

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient android:startColor="#FFAB00"
        android:endColor="#FFAB00">
    </gradient>
</shape>

background2.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient android:startColor="#0091EA"
        android:endColor="#00BFA5">
    </gradient>
</shape>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient android:startColor="#AEEA00"
        android:endColor="#FFD600">
    </gradient>
</shape>

Now create a card view in the main XML file. Here I used  LinearLayout as the root widget, after using the card view. Below the codes that give you an idea of how to customize the card.
You can change it according to your needs.

<?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:orientation="vertical">

    <androidx.cardview.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="173dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="20dp"
        app:cardCornerRadius="8dp">

        <LinearLayout
            android:id="@+id/linearLayout1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@drawable/bg1"
            android:orientation="vertical">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginStart="30dp"
                android:layout_marginTop="20dp"
                android:layout_marginEnd="30dp"
                android:orientation="horizontal">

                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Assam"
                        android:textColor="#000000"
                        android:textSize="22sp" />

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Current Location"
                        android:textColor="#000000"
                        android:textSize="14sp" />
                </LinearLayout>

            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginStart="30dp"
                android:layout_marginTop="20dp"
                android:layout_marginEnd="30dp"
                android:orientation="horizontal">

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="25"
                    android:textColor="#000000"
                    android:textSize="28sp" />

                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginStart="6dp"
                        android:text="o"
                        android:textColor="#000000"
                        android:textSize="13sp" />

                </LinearLayout>

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="18 %"
                    android:textColor="#000000"
                    android:textSize="14sp" />

                <RelativeLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_alignParentEnd="true"
                        android:layout_marginStart="6dp"
                        android:text="11.25 AM"
                        android:textColor="#000000"
                        android:textSize="14sp" />
                </RelativeLayout>
            </LinearLayout>
        </LinearLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="173dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="20dp"
        app:cardCornerRadius="8dp">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@drawable/bg2"
            android:orientation="vertical">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginStart="30dp"
                android:layout_marginTop="20dp"
                android:layout_marginEnd="30dp"
                android:orientation="horizontal">

                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Delhi"
                        android:textColor="@color/white"
                        android:textSize="22sp" />

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="2 days ago"
                        android:textColor="@color/white"
                        android:textSize="14sp" />
                </LinearLayout>

            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginStart="30dp"
                android:layout_marginTop="20dp"
                android:layout_marginEnd="30dp"
                android:orientation="horizontal">

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="39"
                    android:textColor="@color/white"
                    android:textSize="28sp" />

                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginStart="6dp"
                        android:text="o"
                        android:textColor="@color/white"
                        android:textSize="13sp" />

                </LinearLayout>

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="35 %"
                    android:textColor="@color/white"
                    android:textSize="14sp" />

                <RelativeLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_alignParentEnd="true"
                        android:layout_marginStart="6dp"
                        android:text="01.05 PM"
                        android:textColor="#D6D6D6"
                        android:textSize="14sp" />
                </RelativeLayout>
            </LinearLayout>
        </LinearLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="173dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="20dp"
        app:cardCornerRadius="8dp">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@drawable/bg3"
            android:orientation="vertical">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginStart="30dp"
                android:layout_marginTop="20dp"
                android:layout_marginEnd="30dp"
                android:orientation="horizontal">

                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Darjeeling"
                        android:textColor="#000000"
                        android:textSize="22sp" />

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="2 weeks ago"
                        android:textColor="#000000"
                        android:textSize="14sp" />
                </LinearLayout>

            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginStart="30dp"
                android:layout_marginTop="20dp"
                android:layout_marginEnd="30dp"
                android:orientation="horizontal">

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="12"
                    android:textColor="#000000"
                    android:textSize="28sp" />

                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginStart="6dp"
                        android:text="o"
                        android:textColor="#000000"
                        android:textSize="13sp" />

                </LinearLayout>

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="9 %"
                    android:textColor="#000000"
                    android:textSize="14sp" />

                <RelativeLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_alignParentEnd="true"
                        android:layout_marginStart="6dp"
                        android:text="05.00 AM"
                        android:textColor="#000000"
                        android:textSize="14sp" />
                </RelativeLayout>
            </LinearLayout>
        </LinearLayout>
    </androidx.cardview.widget.CardView>
</LinearLayout>