Android - Calling Java from Webview

Question

I want to call Java from Webview.

I have JavaScriptInterface below:

class JavaScriptInterface{

    private Activity activity;

    public JavaScriptInterface(Activity activiy) {
        this.activity = activiy;
    }

    public void open(String message){
        //do something
    }

}

I add JavaScriptInterface

JavaScriptInterface jsInterface = new JavaScriptInterface(this);
webView.getSettings().setJavaScriptEnabled(true);
webView.addJavascriptInterface(jsInterface, "JSInterface");

In my HTML, I have this onclick event:

onclick="window.JSInterface.open('hi');"

I also tried:

onclick="JSInterface.open('hi');"

I have this error in logcat:

04-16 14:55:15.829: W/dalvikvm(721): JNI WARNING: jarray 0x4050cf68 points to non-array object (Ljava/lang/String;)
04-16 14:55:15.829: I/dalvikvm(721): "WebViewCoreThread" prio=5 tid=9 NATIVE
04-16 14:55:15.829: I/dalvikvm(721):   | group="main" sCount=0 dsCount=0 obj=0x40521218 self=0x1f6cf8
04-16 14:55:15.829: I/dalvikvm(721):   | sysTid=729 nice=0 sched=0/0 cgrp=default handle=2059824
04-16 14:55:15.839: I/dalvikvm(721):   | schedstat=( 5717972154 3300872155 567 )
04-16 14:55:15.839: I/dalvikvm(721):   at android.webkit.WebViewCore.nativeTouchUp(Native Method)
04-16 14:55:15.839: I/dalvikvm(721):   at android.webkit.WebViewCore.nativeTouchUp(Native Method)
04-16 14:55:15.839: I/dalvikvm(721):   at android.webkit.WebViewCore.access$3300(WebViewCore.java:53)
04-16 14:55:15.839: I/dalvikvm(721):   at android.webkit.WebViewCore$EventHub$1.handleMessage(WebViewCore.java:1158)
04-16 14:55:15.863: I/dalvikvm(721):   at android.os.Handler.dispatchMessage(Handler.java:99)
04-16 14:55:15.869: I/dalvikvm(721):   at android.os.Looper.loop(Looper.java:130)
04-16 14:55:15.869: I/dalvikvm(721):   at android.webkit.WebViewCore$WebCoreThread.run(WebViewCore.java:629)
04-16 14:55:15.869: I/dalvikvm(721):   at java.lang.Thread.run(Thread.java:1019)
04-16 14:55:15.869: E/dalvikvm(721): VM aborting

How to fix it? Or another way to do it?

Thanks

score 1 · Answer 1 · edited Jan 23 '14 at 04:05

You need to enable Javascript in your WebView by setting

final WebView myWebView = (WebView) findViewById(R.id.webview);
myWebView.setVerticalScrollBarEnabled(false);
myWebView.setHorizontalScrollBarEnabled(false);
WebSettings webSettings = myWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
webSettings.setJavaScriptCanOpenWindowsAutomatically(true);

You need to load your JS in your HTML DOM.

JsInterface jsInterface = new JsInterface();
jsInterface.wordDef = content;
myWebView.addJavascriptInterface(jsInterface, "interfaces");
myWebView.loadUrl("file:///android_asset/some.html");

Call your interface from HTML/JS

/**JAVA CODE **/
public class JsInterface {
 public String someString;
 Context mContext;

 public void JsInterface(Context c){
   mContext = c;
 }

 public String someFunction(){
  Log.v("JSInterface", ""+someString);
  return someString;
 }
}

/* JS Code */
function addData(){
    var data = interfaces.someFunction();
}

Nice overview. Also don't forget `@JavascriptInterface` (needed since API 17+). http://developer.android.com/reference/android/webkit/WebView.html — domen, Oct 09 '13 at 14:48

score 0 · Answer 2 · answered Mar 06 '14 at 02:51

Maybe it's a bit late but...

If you are using Gingerbread (like I'm doing) you hit this error due to a MEGAFAIL (bug) in that OS version. Please read this which explain how to solve this problem http://www.jasonshah.com/handling-android-2-3-webviews-broken-addjavascriptinterface/

In short you can't use native interface in Android 2.3. Instead you need to inject on the flight javascript to provide native call bridging using window.location = "native://somemethod" and then override the ShouldOverrideUrlLoading of the WebClient class to handle native call.

Android - Calling Java from Webview

2 Answers2

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