it seems the right way to open a file to InputStream is shown as follow.
String path = getFilesDir().getAbsolutePath() + File.separator
+ "yahoo" + ".html";
File file = new File(path);
try {
InputStream is = new BufferedInputStream(new FileInputStream(file));
WebArchiveReader wr = new WebArchiveReader() {
@Override
public void onFinished(WebView webView) {
System.out.println("Page loaded");
}
};
if (wr.readWebArchive(is)) {
wr.loadToWebView(webView);
}
} catch (IOException e) {
e.printStackTrace();
}