Tuesday, August 22, 2017

Re: ClassCastException in generics

Could it possibly be that the ArrayBuffer is coming from another browsing context? (iframe)

The isInstanceOfArrayBuffer returns false.

But the the crash happnes here: handleJetFile calls to getLength, then getLength at the entry calls to com.google.gwt....Cast.castToNative(src), without the second arg (jsType)

public abstract class FileDropHandler<FileT> extends InputClientAdapter {
  protected abstract int getLength(FileT buffer);
  protected void handleJetFile(final String file, final FileT buffer) {
Logger.log("Handle jet file. length = " + getLength(buffer));

public class FileDropHandlerGwt extends FileDropHandler<ArrayBuffer> {
protected int getLength(ArrayBuffer buffer) {
return buffer.getByteLength();

вторник, 22 августа 2017 г., 18:08:55 UTC+3 пользователь Thomas Broyer написал:
Could it possibly be that the ArrayBuffer is coming from another browsing context? (iframe)
What would the following output?

private native boolean isInstanceOfArrayBuffer(Object x) /*-{
  return x instanceof $wnd.ArrayBuffer;

On Tuesday, August 22, 2017 at 2:04:30 PM UTC+2, Kirill Prazdnikov wrote:
Sorry, copypaster error, here is the fixed

getType(buffer) = [object ArrayBuffer]
typeOf(buffer) = object

вторник, 22 августа 2017 г., 15:02:49 UTC+3 пользователь Kirill Prazdnikov написал:
Here it is:

getType(buffer) = [object ArrayBuffer]
typeOf(buffer) = [object ArrayBuffer]

private native String getType(Object x) /*-{
return Object.prototype.toString.call(x);

private native String typeOf(Object x) /*-{
return typeof x;

понедельник, 21 августа 2017 г., 21:47:37 UTC+3 пользователь Tony BenBrahim написал:
Take the object you get back from the file reader and run it through the JSNI method below and GWT,log the result. .Let's see if it really is an ArrayBuffer.(I would note the FileReader result is sometimes a String and sometimes an ArrayBuffer).
private native String getType(Object x)/*-{      return Object.prototype.toString.call(x);  }-*/  

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