Android应用重新打开后显示白屏

Question

I have created a very simple app that opens website in phone browser, this is the only code that allows me to open pdf files and sends contacts page correctly, all works perfectly fine apart from one thing, after the app opens and displays web page, if you press back button it displays a white page layout with heading, and you have to press again to exit or if you press home button and go back into app it displays white page again. i am obviously missing something could anyone please show me how to fix.

MainActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Uri uriUrl = Uri.parse("http://www.ribs2go.com.au");
    Intent launchBrowser = new Intent(Intent.ACTION_VIEW, uriUrl);
    startActivity(launchBrowser);

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<WebView  xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/webview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"

Manifest

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

Answer 1

I'm not sure if you realised that your app doesn't load the webpage itself. Your MainActivity just constructs an implicit Intent and passes it to the System. If you have a default browser set, you won't get prompted and it will open your default browser directly. For that matter, your activity_main.xml could be an empty FrameLayout and doesn't have to be a WebView.

With that out of the way, if the intention of your app is simply redirecting to a certain web page (like a bookmark), then the white page that you see is your MainActivity, it usually remains in the backstack after redirecting. That's why pressing back, or choosing your app from the app switcher will show the white page (which is your MainActivity).

Excluding it from the history/backstack might possibly fix the issue (haven't tried it though), give it a shot:

Manifest:

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:noHistory="true"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

let me know if it worked.

Answer 2

When you are tapping back, MainActivity of your application is being displayed. After Starting browser activity, finish the current Activity. In onCreate method on MainActivity,

...

Uri uriUrl = Uri.parse("http://www.ribs2go.com.au");
Intent launchBrowser = new Intent(Intent.ACTION_VIEW, uriUrl);
startActivity(launchBrowser);
finish(); // This is the fix, finish MainActivity

This white screen issue may occur on app launch as well. To fix it, set transparent, full-screen theme to MainActivity.