Develop Reference

Can Android layout be loaded in the C language?

This link says that to make the app display a layout, you create a main_layout.xml file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<Button android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello, I am a Button" />
</LinearLayout>
and then load it in onCreate method:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// main_layout.xml is compiled into the R.layout.main_layout object
setContentView(R.layout.main_layout);
}
My problem is that I am coding in C, and have the C version of "onCreate" method:
JNIEXPORT
void ANativeActivity_onCreate(ANativeActivity *activity, void *savedState,
size_t savedStateSize) {
....
}
is it possible to load the layout and make the app display it in the C language?

C uses "ANativeActivity" that it doesn't has any of Java methods and resources/objects. Even if you manually parse that XML you should MANUALLY implement all Widgets/Components in C.....so it's near impossible due to high amount of work involved in it.
Usually someone chooses C on Android to do "some special work" that is not available on normal Java or due to performance issues on it.

Android App not connecting to internet on emulator

The app does not connect to the internet. I have
<uses-permission android:name="android.permission.INTERNET" />
in my manifest and I checked the other applications on the emulator for example youtube and google search works but the application isn't able to load the page. This is my main java file.
import android.app.Activity;
import android.os.Bundle;
import android.webkit.WebView;
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
WebView myWebview ;
myWebview = (WebView) this.findViewById(R.id.webz);
myWebview.loadUrl("https://en.wikipedia.org/");
}
}
and this is my main activity
<?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"
tools:context="com.example.hoda.myapplication.MainActivity">
<WebView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/webz"></WebView>
</android.support.constraint.ConstraintLayout>
this is the error i get
[ERROR:gl_surface_egl.cc(289)] eglChooseConfig failed with error EGL_SUCCESS

Try enabling javascript and override the webviewclient to avoid redirection:
WebView myWebview ;
myWebview = (WebView) this.findViewById(R.id.webz);
myWebview.getSettings().setJavaScriptEnabled(true);
myWebview.setWebViewClient(new WebViewClient());
myWebview.loadUrl("https://en.wikipedia.org/");
and update the constraints of your WebView:
<WebView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:id="#+id/webz"></WebView>

The problem was with the emulator's graphics I believe as trying #diegoveloper 's solution on the emulator still did not load the page but trying it on an actual android device was successful.

Do this
Restart the emulator (as suggested in another post and in the comments of this post)
If that doesn't work, restart your device.
Worked for me.

Add activity in your AndroidManifest.xml
android:name="com.(your browser activity)"
android:screenOrientation="portrait">

play Youtube with webview carshes

I'm trying to play YouTube video in my application using WebView.
But when I click "Play" the application crashes.
This is my code:
public class Youtube extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.a_video_item);
WebView videoView = (WebView)findViewById(R.id.videoView);
TextView tvTitle = (TextView) findViewById(R.id.VideoTitle);
WebSettings videoViewSettings = videoView.getSettings();
videoViewSettings.setJavaScriptEnabled(true);
videoViewSettings.setPluginState(WebSettings.PluginState.ON);
videoView.setWebChromeClient(new WebChromeClient());
String youtubeID ="XSzE2LLFluE";
tvTitle.setText(youtubeID);
videoView.loadUrl("http://www.youtube.com/embed/" + youtubeID +"?autoplay=1&vq=small");
}
}
And this is my XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<WebView
android:id="#+id/videoView"
android:layout_width="fill_parent"
android:layout_height="200dp"
android:layout_below="#+id/VideoTitle"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"/>
<TextView
android:id="#+id/VideoTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:text="#string/imgdesc"
android:layout_marginRight="10dp"/>
</RelativeLayout>
I'm testing the project with Nexus 5 on Android Studio emulator.

You have to add the two lines of code:
webView.getSettings().setPluginsEnabled(true); webView.getSettings().setJavaScriptEnabled(true);
this will solve the problem. Try it and tell.

I found the issuse.
Beacuse I did the tests on Emulator without Youtube app its crashes.
On a device with Youtube app its working fine.
Now its crasheswhen i click on 'Full screen' button

loadUrl() crashes with CordovaWebView

I know that there are some posts here but they are not solving my problem.
The thing is:
I have a Cordova App (android platform). In my activity_main.xml I have declared a CordovaWebView and I want to call loadUrl() method to load a website that is in my assets folder. When I invoke the method the app crashes showing "UNFORTUNATELY, MyApp HAS STOPPED".
STRANGE THINGS I HAVE NOTICED:
If I emulate using a device with API 10 or 16, this WORKS FINE. If I test it with 17 it does NOT WORK.
If I don't use CordovaWebView and directly invoke: this.loadUrl("file:///android_asset/www/index.html"); it works fine, but it's like I am not using the layouts I define (so I don't have my ad banner).
Any ideas about this problem??
Thanks!
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
android:id="#+id/layout_home"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:id="#+id/layout_body"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:layout_above="#+id/layout_banner"
android:background="#color/abc_search_url_text_normal">
<org.apache.cordova.CordovaWebView
android:id="#+id/webview"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:background="#color/common_signin_btn_dark_text_disabled" />
</LinearLayout>
<RelativeLayout
android:id="#+id/layout_banner"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="#color/wallet_hint_foreground_holo_dark">
</RelativeLayout>
</RelativeLayout>
MainAcitivy.java
public class MainActivity extends CordovaActivity {
CordovaWebView cwv;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
..LOAD ADVERTISEMENT INTO LAYOUT_BANNER...
cwv = (CordovaWebView) findViewById(R.id.webview);
cwv.getSettings().setJavaScriptEnabled(true);
cwv.loadUrl("file:///android_asset/www/index.html");
}

look the doc : https://cordova.apache.org/docs/en/3.5.0/guide_platforms_android_webview.md.html
cwv = (CordovaWebView) findViewById(R.id.cordovaview);
Config.init(this);
cwv.loadUrl(Config.getStartUrl());
you can see a sample here : https://github.com/dam1/sample-android-cordova-webview

Why do you need activity_main.xml and all android stuff, just start a fresh project using cordova command line. You don't need any xml of that sort in standard cordova project.
You've got cordova plugins for displaying admob ads inside cordova web view, see http://plugreg.com/search?q=admob

Why does Android WebView display a black screen?

I've been banging my head against a wall this afternoon trying to get a WebView to work. Below is the code in the main class:
public class fkyougoogle extends Activity {
/** Called when the activity is first created. */
WebView webview;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
webview = (WebView) findViewById(R.id.webview);
webview.getSettings().setJavaScriptEnabled(true);
// WORKS
//webview.loadUrl("http://www.google.com");
// DOESN'T WORK
//webview.loadUrl("http://www.theregister.co.uk");
//webview.loadData("<html><body>hello</body></html>", "text/html", "utf-8");
//webview.loadDataWithBaseURL("fake://", "<html><body>hello</body></html>", "text/html", "utf-8", "http://www.theregister.co.uk/");
}
}
This is Google's "Hello, Webview" example. If I use a WebView and try to access www.google.com then it works fine. If I try to access any other site then it fails including loadData and it just displays a black screen in the emulator. In the end I would like to read from a local file.
is included under the manifest tag and the XML schema is the same as the Hello Webview example.
Am I missing something obvious here? :(

Try changing
android:layout_width="wrap_content"
android:layout_height="wrap_content"
to
android:layout_width="fill_parent"
android:layout_height="fill_parent"
in your main.xml top level LinearLayout
It should look like this:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<WebView
android:id="#+id/webview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>
</LinearLayout>

Try UTF-8 instead of utf-8 for your latter two attempts. I have no problem loading http://www.theregister.co.uk using the same code -- try loading it in the built-in Browser app, and if that fails, you're perhaps encountering some sort of firewall/proxy issue.
Here are a few projects demonstrating simple uses of WebView, from one of my books.

I had similar problem of a WebView being completely blank, but it my case it was caused by a missing android.permission.INTERNET uses-permission.