问题
As we all know, many Android apps display a white screen very briefly before their first Activity comes into focus. This problem is observed in the following cases:
Android apps that extend the global Application class and perform major initializations therein. The
Applicationobject is always created before the firstActivity(a fact that can be observed in the debugger), so this makes sense. This is the cause of the delay in my case.Android apps that display the default preview window before the splash screen.
Setting android:windowDisablePreview = "true" obviously does not work here. Nor can I set the parent theme of the splash screen to Theme.Holo.NoActionBar as described here, because [unfortunately] my splash screen makes use of an ActionBar.
Meanwhile, apps that do not extend the Application class do not show the white screen at startup.
The thing is, ideally the initializations performed in the Application object need to occur before the first Activity is shown. So my question is, how can I perform these initializations on app startup without using an Application object? Possibly using a Thread or Service, I suppose?
This is an interesting problem to think about. I can't bypass it the usual way (by setting the NoActionBar theme), as tragically my Splash screen actually has an ActionBar due to some unrelated reasons.
Note:
I have already referred to the following questions:
How To fix white screen on app Start up?
Android splash screen is white in the beginning?
White screen before splashscreen
White background when Android app start up
Why there is a white screen appears for 1sec when starting to run the apps in Android?
References:
Patterns – Launch screens.
Branded launch screen: the new splash for Android.
Splash Screens the Right Way.
回答1:
The problem with white background is caused because of android's cold start while the app loads to memory, and it can be avoided with this:
public class OnboardingWithCenterAnimationActivity extends AppCompatActivity {
public static final int STARTUP_DELAY = 300;
public static final int ANIM_ITEM_DURATION = 1000;
public static final int ITEM_DELAY = 300;
private boolean animationStarted = false;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
setTheme(R.style.AppTheme);
getWindow().getDecorView().setSystemUiVisibility(
View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_onboarding_center);
}
@Override
public void onWindowFocusChanged(boolean hasFocus) {
if (!hasFocus || animationStarted) {
return;
}
animate();
super.onWindowFocusChanged(hasFocus);
}
private void animate() {
ImageView logoImageView = (ImageView) findViewById(R.id.img_logo);
ViewGroup container = (ViewGroup) findViewById(R.id.container);
ViewCompat.animate(logoImageView)
.translationY(-250)
.setStartDelay(STARTUP_DELAY)
.setDuration(ANIM_ITEM_DURATION).setInterpolator(
new DecelerateInterpolator(1.2f)).start();
for (int i = 0; i < container.getChildCount(); i++) {
View v = container.getChildAt(i);
ViewPropertyAnimatorCompat viewAnimator;
if (!(v instanceof Button)) {
viewAnimator = ViewCompat.animate(v)
.translationY(50).alpha(1)
.setStartDelay((ITEM_DELAY * i) + 500)
.setDuration(1000);
} else {
viewAnimator = ViewCompat.animate(v)
.scaleY(1).scaleX(1)
.setStartDelay((ITEM_DELAY * i) + 500)
.setDuration(500);
}
viewAnimator.setInterpolator(new DecelerateInterpolator()).start();
}
}
}
layout
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
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"
android:background="?colorPrimary"
android:orientation="vertical"
>
<LinearLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:orientation="vertical"
android:paddingTop="144dp"
tools:ignore="HardcodedText"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="16dp"
android:alpha="0"
android:text="Hello world" android:textAppearance="@style/TextAppearance.AppCompat.Widget.ActionBar.Title.Inverse"
android:textColor="@android:color/white"
android:textSize="22sp"
tools:alpha="1"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="8dp"
android:alpha="0"
android:gravity="center"
android:text="This a nice text"
android:textAppearance="@style/TextAppearance.AppCompat.Widget.ActionBar.Subtitle.Inverse"
android:textSize="20sp"
tools:alpha="1"
/>
<Button
android:id="@+id/btn_choice1"
android:layout_width="200dp"
android:layout_height="wrap_content"
android:layout_marginTop="48dp"
android:scaleX="0"
android:scaleY="0"
android:text="A nice choice"
android:theme="@style/Button"
/>
<Button
android:id="@+id/btn_choice2"
android:layout_width="200dp"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:scaleX="0"
android:scaleY="0"
android:text="Far better!"
android:theme="@style/Button"
/>
</LinearLayout>
<ImageView
android:id="@+id/img_logo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:src="@drawable/img_face"
tools:visibility="gone"
/>
</FrameLayout>
img face
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android"
android:opacity="opaque">
<item android:drawable="?colorPrimary"/>
<item>
<bitmap
android:gravity="center"
android:src="@drawable/img_face"/>
</item>
Add this theme to your splashscreen in the manifest
<?xml version="1.0" encoding="utf-8"?>
<resources>
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
<item name="android:windowBackground">@null</item>
</style>
<style name="AppTheme.CenterAnimation">
<item name="android:windowBackground">@drawable/ll_face_logo</item>
</style>
which will produce efect like this
for more details and more solutions you can check this BlogPost
回答2:
please add this line into your app theme
<item name="android:windowDisablePreview">true</item>
for more information : https://developer.android.com/topic/performance/vitals/launch-time#themed
回答3:
Please copy and paste these two lines in your manifest app theme i.e res/styles/AppTheme. then it will work like charm..
<item name="android:windowDisablePreview">true</item>
<item name="android:windowIsTranslucent">true</item>
回答4:
First of all, to remove the white screen read this - https://www.bignerdranch.com/blog/splash-screens-the-right-way/
But more importantly, optimize your initial load and defer any heavy work to when you have time to run it. Post your application class here if you want us to take a look at it.
回答5:
Recommended way of solving this problem is missing in the answers. So I am adding my answer here. The white-screen-at-startup problem occurs because of the initial blank screen that the system process draws when launching the app. A common way to solve this is by turning off this initial screen by adding this to your styles.xml file.
<item name="android:windowDisablePreview">true</item>
But according to android documentation this can result in longer startup time. Recommended way of avoiding this initial white screen according to google is to use activity's windowBackground theme attribute and provide a simple custom drawable for the starting activity.
Like this:
Drawable Layout file, my_drawable.xml
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" android:opacity="opaque">
<!-- The background color, preferably the same as your normal theme -->
<item android:drawable="@android:color/white"/>
<!-- Your product logo - 144dp color version of your app icon -->
<item>
<bitmap
android:src="@drawable/product_logo_144dp"
android:gravity="center"/>
</item>
</layer-list>
Create a new style in your styles.xml
<!-- Base application theme. -->
<style name="AppTheme">
<!-- Customize your theme here. -->
</style>
<!-- Starting activity theme -->
<style name="AppTheme.Launcher">
<item name="android:windowBackground">@drawable/my_drawable</item>
</style>
Add this theme to your starting activity in the Manifest file
<activity ...
android:theme="@style/AppTheme.Launcher" />
And when you want to transition back to your normal theme call setTheme(R.style.Apptheme) before calling super.onCreate() and setContentView()
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// Make sure this is before calling super.onCreate
setTheme(R.style.Theme_MyApp);
super.onCreate(savedInstanceState);
// ...
}
}
This is the recommended way to solve the problem and this is from google Material Design patterns.
回答6:
Have you tried setting theandroid:windowBackground attribute in the theme of your launcher activity, to either a color or a drawable?
For example this:
<item name="android:windowBackground">@android:color/black</item>
when added to the Launcher activity theme will show a black color (rather than the white color) on startup. This is an easy trick to hide long initialisation, while showing your users something, and it works fine even if you subclass the Application object.
Avoid using other constructs (even Threads) for doing long initialisation tasks, because you may end up not being able to control the lifecycle of such constructs. The Application object is the correct place for doing exactly this type of actions.
回答7:
I added the following two lines in my theme under styles.xml
<item name="android:windowDisablePreview">true</item>
<item name="android:windowBackground">@null</item>
Worked like a charm
回答8:
I had same issue, you have to update your style.
style.xml
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
<!-- Customize your theme here. -->
<item name="drawerArrowStyle">@style/DrawerArrowStyle</item>
<item name="android:windowNoTitle">true</item>
<item name="android:windowDisablePreview">true</item>
<item name="android:windowBackground">@null</item>
<item name="android:windowIsTranslucent">true</item>
</style>
Your manifest file should looks like below.
<application
android:name=".MyApplication"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme">
// Other stuff
</application>
Outout:
Hope this would help you.
回答9:
Within the lifecycle callback methods, you can declare how your activity behaves when the user leaves and re-enters the activity. Remember that the way Android is designed, there is a lifecycle for each and every app. If you put too much load to the onCreate() method (which is the method used to load the layout files and initalise any controls you have in it), then the white screen will become more visible, as the layout file will take longer to load.
I suggest using several different methods when starting an activity. Such are the onStart() (being called as the first thing once the app is loaded), onActivityCreated() (being called after the layout is displayed and useful if you are making any data processing upon starting the activity).
To make it easier for you, below is the official activity lifecycle diagram:
回答10:
Did you try to put initialization to onActivityCreated?
Inside Application class :
registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
if(activity.getClass().equals(FirstActivity.class) {
// try without runOnUiThread if it will not help
activity.runOnUiThread(new Runnable() {
@Override
public void run() {
new InitializatioTask().execute();
}
});
}
}
@Override
public void onActivityStarted(Activity activity) {
}
@Override
public void onActivityResumed(Activity activity) {
}
@Override
public void onActivityPaused(Activity activity) {
}
@Override
public void onActivityStopped(Activity activity) {
}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
}
@Override
public void onActivityDestroyed(Activity activity) {
}
});
回答11:
As you are already aware why this white screen is there, as due to background processes or application initialization or large files, so just check below idea for overcome from this.
To prevent this white screen on beginning of the app, one way is splash screen, this is just a way not final and you must have to use.
When you will show splash screen from your splash.xml file, then also this issue will be remain same,
So you have to create ont style in style.xml file for splash screen and there you have to set window background as your splash image and then apply that theme to your splash activity from manifest file. So now when you will run app, first it will set theme and by this way user will be able to see directly splash image instead of white screen.
回答12:
Both properties works
<style name="AppBaseThemeDark" parent="@style/Theme.AppCompat">
<!--your other properties -->
<!--<item name="android:windowDisablePreview">true</item>-->
<item name="android:windowBackground">@null</item>
<!--your other properties -->
</style>
回答13:
Just write the item in values/styles.xml:
<item name="android:windowBackground">@android:color/black</item>
For example, in the AppTheme:
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<item name="windowNoTitle">true</item>
<item name="windowActionBar">false</item>
<item name="android:windowFullscreen">true</item>
<item name="android:windowContentOverlay">@null</item>
<item name="android:windowBackground">@android:color/black</item>
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
</style>
回答14:
Style :-
<style name="SplashViewTheme" parent="Theme.AppCompat.NoActionBar">
<item name="android:windowBackground">@drawable/splash</item>
<item name="windowActionBar">false</item>
<item name="windowNoTitle">true</item>
</style>
In Manifest :-
<activity android:name=".SplashActivity"
android:theme="@style/SplashViewTheme">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
回答15:
Please try this once.
1) Crate a drawable file splash_background.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@color/{your color}" />
<item>
<bitmap
android:layout_width="@dimen/size_250"
android:layout_height="@dimen/size_100"
android:gravity="center"
android:scaleType="fitXY"
android:src="{your image}"
android:tint="@color/colorPrimary" />
</item>
</layer-list>
2) Put this in styles.xml
<style name="SplashTheme" parent="Theme.AppCompat.NoActionBar">
<item name="android:windowBackground">@drawable/background_splash</item>
</style>
3) In your AndroidMainfest.xml set the above theme to Launch activity.
<activity
android:name=".SplashScreenActivity"
android:screenOrientation="portrait"
android:theme="@style/SplashTheme"
android:windowSoftInputMode="stateVisible|adjustResize">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
来源：https://stackoverflow.com/questions/37437037/android-prevent-white-screen-at-startup