I have this weird problem when showing an activity which consists (only) out of a webview.
The first time I start this Activity B by clicking on something in activity A, B is properly loaded and functional. I press the return button, go back to A, then click on the same button to go to B and my webview doesn't show anything. Debugged it tons of times and nothing seems out of the ordinary. There are also no crashes in the stack trace log... This problem by the wway occurs always in debug mode and only sometimes in run mode.
Here is the code for the activity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_spin);
myItem = (Item) getIntent().getSerializableExtra("Item");
initView();
initHandlers();
}
private void initView()
{
webView = findViewById(R.id.webview_spin);
//TODO : webViewClient vs webChromeClient ?
webView.setWebViewClient(new WebViewClient());
webView.setWebChromeClient(new WebChromeClient());
webView.getSettings().setJavaScriptEnabled(true);
String json = new Gson().toJson(myItem);
webView.loadUrl("file:///android_asset/item.html?item="+json);
}
private void initHandlers()
{
OrientationEventListener orientationEventListener = new OrientationEventListener(this) {
#Override
public void onOrientationChanged(int orientation) {
webView.reload();
}
};
orientationEventListener.enable();
}
FYI this problem occured before setting the orientationlistener.
That looks like somehow the render process of the WebView is failing. You could store the WebViewClient you created on a variable and check the result of its method onRenderProcessGone() to check if it is rendering the second time you load the activity. Here you have all the WebViewClient methods: https://developer.android.com/reference/android/webkit/WebViewClient
Related
so I have a working webview that is simple, but most of the work is done in the main activity. I am trying to break it out to its own little class so I can load other classes into the main activity on the fly. I am stuck on how to do this. I have tried this a few times and been debugging it but I just dont know if I am using the right findByValue(R.id.webView); thing here. it keeps giving me a
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.webkit.WebView.findViewById(int)' on a null object reference
issue. I have tried passing the reference in as a parameter and also hard coded it. I am missing something but dont know what. There is a WebView in my activity_main that is called wevView that is what I am trying to find out where i'm did mistake.
Thanks for any help with this.
So this is my webview class:
public class NewWebView {
//variables need for webview
private final String myPage = "http://www.google.com";
WebView myWebView = null;
//consturctor
public NewWebView(){}
//This method creates the WebView
public void createWebView(WebView webView)
{
//WebView code
//Find the Webview in the Activity.xml file
//myWebView = webView;
myWebView = (WebView)myWebView.findViewById(R.id.webview);
// myWebView = (android.webkit.WebView)findViewById(R.id.webview);
//Use the custom WebViewClient for internal app browsing
myWebView.setWebViewClient(new MyWebViewClient());
//now for enabling the settings
WebSettings webSettings = myWebView.getSettings();
//Enable JavaScript
webSettings.setJavaScriptEnabled(true);
//Enable andriod zoom features
webSettings.setBuiltInZoomControls(true);
//Loading the Url
myWebView.loadUrl(myPage);
}
//Methods Used for WebViewer
//custom WebViewClent needed for internal app navigatiion
private class MyWebViewClient extends WebViewClient
{
public boolean shouldOverRideUrlLoading(android.webkit.WebView view, String url)
{
if(Uri.parse(url).getHost().equals(myPage))
{
//this is Apivita remain in the APP
return false;
}
/*
//if it is not in my site redirect it to mobile browers
Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
startActivity(intent);
return true;
*/
return true;
}
}
//Enable the use of the system back button for navigation
public boolean onKeyDown(int keyCode, KeyEvent event)
{
//if the back button was pushed
if((keyCode == KeyEvent.KEYCODE_BACK) && myWebView.canGoBack())
{
myWebView.goBack();
return true;
}
//if not
return false;
}
}
and here is the main activity
public class MainActivity extends AppCompatActivity {
WebView myWebView = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//create the webview
myWebView = (android.webkit.WebView)findViewById(R.id.webview);
NewWebView apWebView = new NewWebView();
apWebView.createWebView(myWebView);
}
}
It looks like you are finding your webview in the main activity and then passing it into your class. In your custom class, you're then trying to find another view, which you technically already have. So its trying to find a webview, inside of the webview. It obviously can't find this, so it's null.
In theory, you should be able to just use myWebView = webView;, however, you need to make sure that it is finding it in the first place.
I am very new to Andriod Programming and this is probably very basic question.
In my Application, the first page contains just button (for simplicity) login button.
After the user clicks login button it displays the toast and then I need to navigate to new class(page B) where I want to connect to a specific health sensor.
Problem
1. I tried implementing the just the basic part with onClickListener for button and then when clicked, go to next page, where enable Bluetooth,etc. I could not get to next page
MainActivity.java :
public class MainActivity extends AppCompatActivity {
Button button;
PollingTest pd;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button)findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getBaseContext(),"Logged In",Toast.LENGTH_SHORT).show();
pd = new PollingTest();
pd.call();
}
});
}
}
Second Page (Where wanted to Control BT). Never got to this page while testing on the tablet: -
For now just included if I could get a Toast atleast from this page: -
public class PollingTest extends Activity {
BluetoothAdapter btAdapter;
Button btn2;
protected void call() {
//super.onCreate(savedInstanceState);
//setContentView(R.layout.pairinglistactivity);
btn2 = (Button)findViewById(R.id.pollB);
btn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "hello", Toast.LENGTH_LONG).show();
}
});
}
}
Here app crashes after clicking on Login button in first page.
I have actually got some different errors with different code, I was not able to make proper Toast or turn BT on in the second page as it was trying them in static method.( very Confusing:( )
Please help me. I know this v v basic Q..
EDIT:
Sorry, this Q is already answered here: -
Moving from one activity to another Activity in Android
You don't start an activity by instantiating it like a normal Java class. So this is wrong
pd = new PollingTest();
pd.call();
you should be using an Intent
and follow the Activity Lifecycle
so you would want something like
Intent i = new Intent(MainActivity.this, PollingTest.class);
startActivity(i);
then override onCreate() in PollingTest.java and put what is in call() in there or call that method from onCreate().
Also, a Toast should use Activity Context
What are the settings to enable or disable in WebView to do this?
If you want to use a webview with exactly the same features as the native android browser, you have to check MANY options and settings. A WebView is made to NOT use all of the browsers options and settings for better performance and for having more controll on what the users can and can not do while browsing. to figure out all the opportunities you should read through the api documentation here:
http://developer.android.com/reference/android/webkit/WebView.html
For some further dealing and handling with the WebView class also here are some usefull sample codelines:
http://pankajchunchun.wordpress.com/2013/01/09/example-of-webview-with-result-handler-and-connection-timeout-handler/
I hope this will help you.
this is the webview example source..
what kind of setting do you wanna know??
public class MainActivity extends Activity {
WebView webview;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
webview = (WebView)findViewById(R.id.webview);
webview.setWebViewClient(new WebClient());
WebSettings set = webview.getSettings();
set.setJavaScriptEnabled(true);
set.setBuiltInZoomControls(true);
webview.loadUrl("http://www.google.com");
findViewById(R.id.btnStart).setOnClickListener(onclick);
}
OnClickListener onclick =new OnClickListener() {
#Override
public void onClick(View v) {
String url= null;
EditText add = (EditText)findViewById(R.id.add);
url = add.getText().toString();
webview.loadUrl(url);
}
};
class WebClient extends WebViewClient {
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
}
In addition to #Ssam's answer, you might want to manage the back button press so your app/Activity doesn't get closed on back press.
#Override
public void onBackPressed() {
if (webview.canGoBack()) {
webview.goBack();
}else
super.onBackPressed();
}
where webview is your webview
Right now when I push a specific button it starts an intent to open a web page into a webView, but instead it opens a Browser Application, revealing the address bar which is not what I want.
After doing some research I found out I can use the shouldOverrideUrlLoading() method to stop this from happening and just open the page in a webView, but I don't know how to implement this method in my code, help would be greatly appreciated!
This is what I have in the class where I'm opening the web page:
public class Codes extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.codes);
View titleView = getWindow().findViewById(android.R.id.title);
if (titleView != null) {
ViewParent parent = titleView.getParent();
if (parent != null && (parent instanceof View)) {
View parentView = (View)parent;
parentView.setBackgroundColor(Color.rgb(228, 108, 10));
}
}
WebView codes = (WebView)findViewById(R.id.codesWebView);
codes.getSettings().setJavaScriptEnabled(true);
codes.loadUrl("http://dev10.affirmaconsulting.com:24009/keyentry");
shouldOverrideUrlLoading(codes, "http://dev10.affirmaconsulting.com:24009/keyentry");
}
}
I had this same problem, that pages were not loading in my webview but instead via the browser application. I resolved the issue by implementing a WebViewClient class and overriding the shouldOverrideUrlLoading method.
WebViewClient webClient = new WebViewClient()
{
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url)
{
return false;
}
};
webView.setWebViewClient(webClient);
The following link proved to be helpful:
http://www.firstdroid.com/2010/08/05/override-url-loading-in-webview-android-tutorial/
We do this exact task in one of our activities and haven't ran into this issue. Here is what ours looks like:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.document_viewer_activity);
WebView wv = (WebView) findViewById(R.id.documentViewerWebview);
wv.getSettings().setJavaScriptEnabled(true);
String url = getString(R.string.document_viewer_url) +
getIntent().getExtras().getString("media");
wv.loadUrl(url);
}
With the webview defined in the layout file looking like this:
<WebView
android:id="#+id/documentViewerWebview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>
Hope this helps.
I have been trying to put a back button progress bar in a webview and keep the url loading within my app instead of using the android default web browser.
If I manage to keep to browsing within the app and keep the back button the progress bar never shows up if I manage to get the progress bar to show up the code at the bottom for shouldoverideurl come up never read and the default browser launches, I tried all the google tutorials and solution but none of them work. I am currently using google.. Can anyone help??
public class livebrad extends Activity {
WebView mWebView;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// Adds Progrss bar Support
this.getWindow().requestFeature(Window.FEATURE_PROGRESS);
setContentView(R.layout.brows);
// Makes Progress bar Visible
getWindow().setFeatureInt( Window.FEATURE_PROGRESS, Window.PROGRESS_VISIBILITY_ON);
// Get Web view
mWebView = (WebView) findViewById( R.id.webView ); //This is the id you gave
//to the WebView in the main.xml
mWebView.getSettings().setJavaScriptEnabled(true);
mWebView.getSettings().setSupportZoom(true); //Zoom Control on web (You don't need this
//if ROM supports Multi-Touch
mWebView.getSettings().setBuiltInZoomControls(true); //Enable Multitouch if supported by ROM
// Load URL
mWebView.loadUrl("http://www.bbc.co.uk");
// Sets the Chrome Client, and defines the onProgressChanged
// This makes the Progress bar be updated.
final Activity MyActivity = this;
mWebView.setWebChromeClient(new WebChromeClient() {
public void onProgressChanged(WebView view, int progress)
{
//Make the bar disappear after URL is loaded, and changes string to Loading...
MyActivity.setTitle("Loading...");
MyActivity.setProgress(progress * 100); //Make the bar disappear after URL is loaded
// Return the app name after finish loading
if(progress == 100)
MyActivity.setTitle(R.string.app_name);
}class HelloWebViewClient extends WebViewClient {
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
}
});
}//End of Method onCreate
}
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class SandbarinFacebook extends Activity {
WebView mWebView;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fb);
final ProgressDialog pd = ProgressDialog.show(this, "", "Loading...",
true);
mWebView = (WebView) findViewById(R.id.webkitWebView1);
mWebView.getSettings().setJavaScriptEnabled(true);
mWebView.getSettings().setSupportZoom(true);
mWebView.getSettings().setBuiltInZoomControls(true);
mWebView.setWebViewClient(new WebViewClient() {
#Override
public void onPageFinished(WebView view, String url) {
if(pd.isShowing() && pd!=null)
{
pd.dismiss();
}
}
});
mWebView.loadUrl("http://m.facebook.com/sandbarathens");
}
}
If you want show progress bar each time user clicks links, add code to show progressbar in your shouldOverrideUrlLoading() method.
You just missed this statement.
mWebView.setWebViewClient(..)