albertzak/MainActivity.java

## MainActivity.java
package gq.icctv.webviewdemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.webkit.JavascriptInterface;
import android.webkit.WebResourceRequest;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

    WebView webview = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        webview = ((WebView) findViewById(R.id.webview));
        webview.getSettings().setJavaScriptEnabled(true);
        webview.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
                return false;
            }
        });
    }

    public void loadUrl(View button) {
        webview.loadUrl("http://google.com");
    }

    public void loadHtml(View button) {
        String summary = "<html>" +
                    "<body style='background: #BCDFE6; color: #FFF'>" +
                        "<marquee>" +
                            "<h1>I'm a web page</h1>" +
                        "</marquee>" +
                        "<img width='400' src='https://s-media-cache-ak0.pinimg.com/originals/4f/e1/17/4fe1179802e65971ccaa2e86f592a324.gif'></img>" +
                    "</body>" +
                "</html>";

        webview.loadData(summary, "text/html", null);
    }

    public void injectJS(View button) {
        Random generator = new Random();
        int randomHue = 60 + generator.nextInt(240);
        String js = "" +
                "document.body.style.WebkitFilter = 'hue-rotate(" + randomHue + "deg) saturate(3) sepia(0.1)';\n" +
                "var field = document.querySelector('.gsfi');\n" +
                "field.value = 'Hello from injected JS \uD83E\uDD84';";
        webview.evaluateJavascript(js, null);
    }

    public void injectObject(final View button) {
        class Toaster {
            @JavascriptInterface
            public void toast() {
                Toast toast = Toast.makeText(button.getContext(), "Here's your Toast  \uD83C\uDF5E", Toast.LENGTH_LONG);
                toast.show();
            }
        }

        webview.addJavascriptInterface(new Toaster(), "toaster");


        String summary = "<html>" +
                    "<body>" +
                       "<button onClick='javascript:toaster.toast()'>" +
                            "This HTML Button can show a Toast" +
                        "</button>" +
                    "</body>" +
                "</html>";

        webview.loadData(summary, "text/html", null);
    }
}
	package gq.icctv.webviewdemo;

	import android.support.v7.app.AppCompatActivity;
	import android.os.Bundle;
	import android.view.View;
	import android.webkit.JavascriptInterface;
	import android.webkit.WebResourceRequest;
	import android.webkit.WebView;
	import android.webkit.WebViewClient;
	import android.widget.Toast;

	import java.util.Random;

	public class MainActivity extends AppCompatActivity {

	WebView webview = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_main);

	webview = ((WebView) findViewById(R.id.webview));
	webview.getSettings().setJavaScriptEnabled(true);
	webview.setWebViewClient(new WebViewClient() {
	@Override
	public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
	return false;
	}
	});
	}

	public void loadUrl(View button) {
	webview.loadUrl("http://google.com");
	}

	public void loadHtml(View button) {
	String summary = "<html>" +
	"<body style='background: #BCDFE6; color: #FFF'>" +
	"<marquee>" +
	"<h1>I'm a web page</h1>" +
	"</marquee>" +
	"<img width='400' src='https://s-media-cache-ak0.pinimg.com/originals/4f/e1/17/4fe1179802e65971ccaa2e86f592a324.gif'></img>" +
	"</body>" +
	"</html>";

	webview.loadData(summary, "text/html", null);
	}

	public void injectJS(View button) {
	Random generator = new Random();
	int randomHue = 60 + generator.nextInt(240);
	String js = "" +
	"document.body.style.WebkitFilter = 'hue-rotate(" + randomHue + "deg) saturate(3) sepia(0.1)';\n" +
	"var field = document.querySelector('.gsfi');\n" +
	"field.value = 'Hello from injected JS \uD83E\uDD84';";
	webview.evaluateJavascript(js, null);
	}

	public void injectObject(final View button) {
	class Toaster {
	@JavascriptInterface
	public void toast() {
	Toast toast = Toast.makeText(button.getContext(), "Here's your Toast \uD83C\uDF5E", Toast.LENGTH_LONG);
	toast.show();
	}
	}

	webview.addJavascriptInterface(new Toaster(), "toaster");


	String summary = "<html>" +
	"<body>" +
	"<button onClick='javascript:toaster.toast()'>" +
	"This HTML Button can show a Toast" +
	"</button>" +
	"</body>" +
	"</html>";

	webview.loadData(summary, "text/html", null);
	}
	}