由于生成签名的APK时由于Android 3.1.2中的imageview而导致的错误

Question

I can able to install debug apk or build apk in mobile below is the xml, i am using only drawable and not like drawable-21 or 24 like that so please have look in my xml file i am using png images only...................................................................

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/gradient_background">

    <ImageView
        android:id="@+id/a"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginTop="18dp"
        android:src="@drawable/u_text_logo"
        app:layout_constraintBottom_toTopOf="@+id/imageView1"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:src="@drawable/your_friend"
        app:layout_constraintBottom_toTopOf="@+id/imageView3"
        app:layout_constraintEnd_toEndOf="parent" />

    <ImageView
        android:id="@+id/imageView3"
        android:layout_width="182dp"
        android:layout_height="223dp"

        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:src="@drawable/web_hi_res"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.497"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.578" />

    <ProgressBar
        android:id="@+id/progressBar3"
        android:layout_width="80dp"
        android:layout_height="55dp"

        android:layout_marginBottom="108dp"
        android:layout_marginTop="8dp"
        android:padding="1dp"
        android:theme="@style/AppTheme.WhiteAccent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="1.0" />


</android.support.constraint.ConstraintLayout>

but when i generate signed apk then i getting error crash like this

java.lang.RuntimeException: Unable to start activity ComponentInfo{xxx.xxx.xx/xxx.xxx.xx.SplasScreen}: android.view.InflateException: Binary XML file line #9: Binary XML file line #9: Error inflating class ImageView
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2455)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2515)
    at android.app.ActivityThread.access$1000(ActivityThread.java:154)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1379)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:157)
    at android.app.ActivityThread.main(ActivityThread.java:5571)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:745)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:635)
Caused by: android.view.InflateException: Binary XML file line #9: Binary XML file line #9: Error inflating class ImageView
    at android.view.LayoutInflater.inflate(LayoutInflater.java:543)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:427)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
    at android.support.v7.app.ag.b(Unknown Source)
    at android.support.v7.app.r.setContentView(Unknown Source)
    at hemanth.com.vtuquestionpaper2017.SplasScreen.onCreate(Unknown Source)
    at android.app.Activity.performCreate(Activity.java:6357)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2408)
    ... 9 more
Caused by: android.view.InflateException: Binary XML file line #9: Error inflating class ImageView
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:786)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:708)
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:839)
    at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:802)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:519)
    ... 17 more
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.at.d()' on a null object reference
    at android.support.v7.widget.AppCompatImageView.setImageDrawable(Unknown Source)
    at android.widget.ImageView.<init>(ImageView.java:154)
    at android.widget.ImageView.<init>(ImageView.java:140)
    at android.support.v7.widget.AppCompatImageView.<init>(Unknown Source)
    at android.support.v7.widget.AppCompatImageView.<init>(Unknown Source)
    at android.support.v7.app.av.a(Unknown Source)
    at android.support.v7.app.ag.a(Unknown Source)
    at android.support.v7.app.ag.onCreateView(Unknown Source)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:750)
    ... 21 more

Answer 1

This issue is created in only release build becuase proguard removes some useful classes or method from code.

You can read and understand rules for proguard from Google dev docs . or Basics

For now you can add this rule to your proguard-rules.pro file

-keep class android.support.v7.widget.** { *; }

Try clean build and make release apk after adding this rule.

Here is proguard-rules.pro located

I tell you shortcut too ;)

Remove proguard setting so android will not remove any classes for shrinking code. in your app level build.gradle change below

buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

to this

buildTypes {
    release {
    }
}

Then sync and build apk. It should run.

Update

Proguard is free Java class file shrinker, optimizer, obfuscator, and preverifier. It detects and removes unused classes, fields, methods, and attributes. It optimizes bytecode and removes unused instructions. It renames the remaining classes, fields, and methods using short meaningless names.

Answer 2

Try with adding below line in your activity's onCreate() method:

AppCompatDelegate.setCompatVectorFromResourcesEnabled(true);

Add below attribute to ImageView in your xml:

app:srcCompact 

instead of android:src .