points:
# do not run on android emulator 2.3.x. there is a severe bug and so far not resolved. run on android sdk api >= 8
# put the index.html file in assets folder
# click on javaButton will change the background color of the webView by calling a Js function
# click on the link on webView will change the text of the javaButton
# for debugging purpose: console.log() in js can be viewed on android logcat by implementing onConsoleMessage(ConsoleMessage cm)
index.html
<html>
<script type="text/javascript">
function changeBackgroundColor() {
console.log('Inside changeBackgroundColor');
if ( document.body.style.background == 'red' ) {
document.body.style.background = 'blue';
} else {
document.body.style.background = 'red';
}
}
</script>
<body>
<a onClick="window.JsInterface.onClickJavascriptButton()"> Click me, i am JS Button </a>
</body>
</html>
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button android:id="@+id/bt_javaButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/buttonText"
android:padding="5dp"
android:onClick="onClickJavaButton"/>
<WebView
android:id="@+id/wv_main"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1" />
</LinearLayout>
string.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">Js-Java, Interfacing</string>
<string name="buttonText">This is a Java Button</string>
<string name="buttonText2">I am clicked from JS</string>
</resources>
MyActivity.java
package com.example;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.webkit.*;
import android.widget.Button;
public class MyActivity extends Activity
{
private static final String TAG = MyActivity.class.getSimpleName();
private Button mJavaButton;
private WebView mWebView;
private Handler mHandler;
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
mHandler = new Handler();
mJavaButton = (Button) findViewById(R.id.bt_javaButton);
mWebView = (WebView) findViewById(R.id.wv_main);
// Enabling JS
mWebView.getSettings().setJavaScriptEnabled(true);
// Java and Javascript interfacing
mWebView.addJavascriptInterface(new JavascriptInterface(), "JsInterface");
// for debugging, this will handle the console.log() in javascript
mWebView.setWebChromeClient(new WebChromeClient() {
@Override
public boolean onConsoleMessage(ConsoleMessage cm) {
Log.d(TAG, cm.message() + " #" + cm.lineNumber() + " --" + cm.sourceId() );
return true;
}
});
mWebView.loadUrl("file:///android_asset/index.html");
}
public void onClickJavaButton (View mView) {
mWebView.loadUrl("javascript:changeBackgroundColor()");
}
class JavascriptInterface {
JavascriptInterface() {}
public void onClickJavascriptButton() {
Log.d(TAG, "onClickJavascriptButton entered");
mHandler.post(new Runnable() {
public void run() {
Log.d(TAG, "onClickJavascriptButton inside run");
if (mJavaButton.getText().toString().compareTo(getResources().getString(R.string.buttonText)) == 0)
mJavaButton.setText(R.string.buttonText2);
else
mJavaButton.setText(R.string.buttonText);
}
});
}
}
}
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