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using javascript in android webview

I'm trying to start an activity from a javascript interface in my webview. The example shows a toast. How could i call a class instead of a toast?

public class JavaScriptInterface {
Context mContext;

/** Instantiate the interface and set the context */
JavaScriptInterface(Context c) {
    mContext = c;
}

/** Show a toast from the web page */
public void showToast(String toast) {
    Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
}
}

this for the html page.

<input type="button" value="Say hello" onClick="showAndroidToast('Hello Android!')" />

<script type="text/javascript">
function showAndroidToast(toast) {
    Android.showToast(toast);
}

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1 Answer

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by (71.8m points)

You have to first register the JavaScriptInterface on your webview. JavaScriptInterFace can be a inner class as shown below. This class will have a function that you can call from html page( via javaScript ) and inside this function you can write code to change activity.

Here is the working solution for you:

public class JavascriptInterfaceActivity extends Activity {
    /** Called when the activity is first created. */


    WebView wv;

    JavaScriptInterface JSInterface;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        wv = (WebView)findViewById(R.id.webView1);

        wv.getSettings().setJavaScriptEnabled(true);
        // register class containing methods to be exposed to JavaScript

        JSInterface = new JavaScriptInterface(this);
        wv.addJavascriptInterface(JSInterface, "JSInterface"); 

        wv.loadUrl("file:///android_asset/myPage.html");

    }


    public class JavaScriptInterface {
        Context mContext;

        /** Instantiate the interface and set the context */
        JavaScriptInterface(Context c) {
            mContext = c;
        }

        @android.webkit.JavascriptInterface
        public void changeActivity()
        {
            Intent i = new Intent(JavascriptInterfaceActivity.this, nextActivity.class);
            startActivity(i);
            finish();
        }
    }
}

Here is the html page

<html>
<head>
<script type="text/javascript">
function displaymessage()
{
JSInterface.changeActivity();
}
</script>
</head>

<body>
<form>
<input type="button" value="Click me!" onclick="displaymessage()" />
</form>
</body>
</html>

Hope this helps...


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