Android : callback function from java script to java

Question

I have created an application in which i am using webview and loading a simple static html page. I am calling a java script function from activity but i am unable to call a function from java script. I have tried few of the link , but it didn't work .
Javascript Callback function pass to Android
I cannot call an android function from javascript
Here is my code. Thank you in advance.

acitivity_main.xml

<Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Call JavaScript Function"
        android:onClick="callJavaScript" />

<WebView
    android:id="@+id/myWebView"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />

index.html

<html>
<head>
<script type="text/javascript">
        function displayMessage(){
            document.getElementById('test1').innerHTML = 'This is from java script.';
            Android.returnResult();
        }
    </script>
</head>
<body>
    <h1 id="test1">Hello World</h1>
</body>
</html>

Main activity has following two functions .

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myWebView = (WebView) this.findViewById(R.id.myWebView);
        myWebView.getSettings().setJavaScriptEnabled(true);
        myWebView.addJavascriptInterface(new JavaScriptHandler(this), "Android");
        myWebView.loadUrl("file:///android_asset/index.html");
    }

    public void callJavaScript(View view) {
        Log.v(null, "Calling java Script");
        myWebView.loadUrl("javascript:displayMessage()");
    }

This is the JavaScriptHandler class

public class JavaScriptHandler {
    Context mContext;

    public JavaScriptHandler(Context context) {
        mContext = context;
    }

    public void returnResult() {
        Log.v(null, "result received");
    }
}

Kindly add alert statements in your javascript method to see if you javascript method is getting called properly. Otherwise I dont see any problem in your implementation. — Arunkumar
– Arunkumar, Commented Nov 27, 2013 at 13:54
Thank you for replying , i have added a line to change the html text when java script is getting called and it was working anyway i got the answer looks like i had to use the annotation. — Rana Ranvijay Singh
– Rana Ranvijay Singh, Commented Nov 28, 2013 at 4:51

Hardik Trivedi · Accepted Answer · 2013-11-27 13:57:35Z

5

Make it

@JavascriptInterface
public void returnResult() {
    Log.v(null, "result received");
}

This annotation allows exposing methods to JavaScript.

answered Nov 27, 2013 at 13:57

Hardik Trivedi

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