package fr.free.nrw.commons.auth;

import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.webkit.WebView;

import fr.free.nrw.commons.R;

public class SignupActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d("SignupActivity", "Signup Activity started");

        WebView webView = new WebView(this);
        setContentView(webView);
        //myWebView.loadUrl("https://commons.wikimedia.org/w/index.php?title=Special:CreateAccount&returnto=Main+Page");

        //Mobile page, looks better than the above
        webView.loadUrl("https://commons.m.wikimedia.org/w/index.php?title=Special:CreateAccount&returnto=Main+Page&returntoquery=welcome%3Dyes");

        //After Create Account button is pressed within WebView, it brings user to https://commons.wikimedia.org/wiki/Main_Page. So can we just override that URL?
        //Do we NEED to enable JS? Validation seems to work fine here
    }

}

package fr.free.nrw.commons.auth;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.webkit.WebView;
import android.webkit.WebViewClient;

import fr.free.nrw.commons.R;

public class SignupActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d("SignupActivity", "Signup Activity started");

        WebView webView = new WebView(this);
        setContentView(webView);

        webView.setWebViewClient(new MyWebViewClient());
        //myWebView.loadUrl("https://commons.wikimedia.org/w/index.php?title=Special:CreateAccount&returnto=Main+Page");
        //Mobile page, looks better than the above
        webView.loadUrl("https://commons.m.wikimedia.org/w/index.php?title=Special:CreateAccount&returnto=Main+Page&returntoquery=welcome%3Dyes");

        //After Create Account button is pressed within WebView, it brings user to https://commons.m.wikimedia.org/w/index.php?title=Main_Page&welcome=yes. So can we just override that URL?
        //Do we NEED to enable JS? Validation seems to work fine here
    }

    private class MyWebViewClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (Uri.parse(url).getHost().equals("www.example.com")) {
                // This is my web site, so do not override; let my WebView load the page
                return false;
            }
            // Otherwise, the link is not for a page on my site, so launch another Activity that handles URLs
            Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
            startActivity(intent);
            return true;
        }
    }
}

Change URLs and add MyWebViewClient
Change URLs and add MyWebViewClient
