Something other than an int was returned from JSNI method

Question

I am running a GWT application in hosted mode. Sporadically I get a strange HostedModeException complaining about the type of the JS value returned from JSNI. Sometimes it is during deserialization:

 com.google.gwt.dev.shell.HostedModeException: Something other than an int was returned from JSNI method '@com.google.gwt.user.client.rpc.impl.ClientSerializationStreamReader::readInt()': JS value of type boolean, expected int
    at com.google.gwt.dev.shell.JsValueGlue.getIntRange(JsValueGlue.java:266)
    at com.google.gwt.dev.shell.JsValueGlue.get(JsValueGlue.java:144)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeInt(ModuleSpace.java:247)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeInt(JavaScriptHost.java:75)
    at com.google.gwt.user.client.rpc.impl.ClientSerializationStreamReader.readInt(ClientSerializationStreamReader.java)

sometimes at:

 com.google.gwt.dev.shell.HostedModeException: Something other than an int was returned from JSNI method '@com.google.gwt.user.client.impl.DOMImpl::eventGetTypeInt(Ljava/lang/String;)': JS value of type null, expected int
    at com.google.gwt.dev.shell.JsValueGlue.getIntRange(JsValueGlue.java:266)
    at com.google.gwt.dev.shell.JsValueGlue.get(JsValueGlue.java:144)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeInt(ModuleSpace.java:247)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeInt(JavaScriptHost.java:75)
    at com.google.gwt.user.client.impl.DOMImpl.eventGetTypeInt(DOMImpl.java)
    at com.google.gwt.user.client.impl.DOMImpl.eventGetTypeInt(DOMImpl.java:62)
    at com.google.gwt.user.client.DOM.eventGetType(DOM.java:602)
    at com.google.gwt.user.client.Event$.getTypeInt$(Event.java:695)
    at com.extjs.gxt.ui.client.util.BaseEventPreview.onPreviewNativeEvent(BaseEventPreview.java:139)

once again at

com.google.gwt.dev.shell.HostedModeException: Something other than a float was returned from JSNI method '@com.extjs.gxt.ui.client.util.Util::parseFloat(Ljava/lang/String;F)': JS value of type boolean, expected float
    at com.google.gwt.dev.shell.JsValueGlue.get(JsValueGlue.java:118)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeFloat(ModuleSpace.java:235)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeFloat(JavaScriptHost.java:67)
    at com.extjs.gxt.ui.client.util.Util.parseFloat(Util.java)
    at com.extjs.gxt.ui.client.core.El.getFrameSize(El.java:1081)
    at com.extjs.gxt.ui.client.core.El.setSize(El.java:2702)
    at com.extjs.gxt.ui.client.widget.BoxComponent.setSize(BoxComponent.java:501)
    at com.extjs.gxt.ui.client.widget.BoxComponent.setHeight(BoxComponent.java:320)

Can anyone help me on this? I am using GWT 2.4.0, Google Chrome 16.0.912.75 and GWT Developer Plugin 1.0.9738.

I would like to help, as I also get this kind of random Exception every now and then... but I have no idea! Anyway, it doesn't affect my debugging usually, so I just live with it... but it would be nice to know what's behind that. — Renato
May case was like yours, happened once a month or so, but now in the project I am currently working on this is happening recurrently, many times a day. That's why I feel there may be something wrong with my configuration. Unfortunately it is also difficult to reproduce. In jusio's word, it's magical. — Saintali
This question is duplicated at stackoverflow.com/questions/9984298/… where a work-around is given. — Glenn

jusio jusio · Accepted Answer · 2012-01-18T16:28:58

For some magical reason chrome works very badly with GWT DevMode. Random null pointer exception while parsing JSON, JSNI return types errors when working with GXT, remote death exceptions are a very common problems. It is known problem and that's why most people are not using GWT DevMode with Chrome.

Something other than an int was returned from JSNI method

1 Answers