nimo frey

Does anyone know the difference of

Calendar cal = Calendar.getInstance(); cal.setTimeInMillis(ms)

and that:

Date a = new Date(ms);

Which one should I prefer?

Hello both,

sorry sorry. I was so blind! Yes, you are absolutely right.

It is if you make that a field of the object.

I like JV’s suggestion of an automatically incremented field.

I was lost in fussiness;) (Serializable objects and so on..). But now it is clear!

Thank you for your patient!

I guess, I dont want to use the identityHashCode.

It is better to use a real unique id. However, I do not persist the entity in a database, so I am not able to use a database-id-field.

I guess, I cannot use the

UUID a = UUID.randomUUID();

When I generate a UUID for the instance x and the client sends that UUID back to me, the instance x is no more binded to that UUID.
So I cannot compare it with the servers UUID as generating a new one for the instance x results in another UUID. I cannot use a singleton-class or the like.


Maybe, this is the right thing to do:
UUID b = UUID.fromString(this.toString());

I dont know.

However, I guess, the best is to use override the toString()-Method of my Object and use the String as a Identifier.

Both, Thanks for your help!

Oh, actually I have no collisions - all my instances are identifiable via the string version of the hashCode.

So what should I use instead? Should I override the toString-Version for identification?

So I do not use this '1448505687' but use the string-version "hobbies: soccer|name: paul|age:22|state:null". Is this better?

1) I know. I wrote my hashCode/equals-Method with these methods.

2) I am generating the hashCode of an instance and cast it to a string X. This string, I gave it to the client (for example: web-view). When client sends the X to me, I can look, what object it is by using String.valueOf(_o.hashCode).equals(X).

As I stated before: The client has no java-object, so I cannot use _o.equals(X), because X is not a Java-Object, it is a string-identification of the java-object.

The only question I have is:

Should I use a toString-Method of the instance or can I rely on the computed hashCode (which is also unique) to identify my object-instance from the client to the server.

Actually it works without failure, but I am not sure, if I made it totally right.

I use the Objects.hash and Objects.equals-Methods of Java7 to override hash/equals-Method. All works fine.

I have this question:

Can I use the hashCode of an instance for temporarly identification or should I use a string-version (by overriding toString) to identify this object.

For example:

The instance a of type O is represented by the hashCode '1448505687' and this string-version "hobbies: soccer|name: paul|age:22|state:null".

I have a list of O's and want to look, if the list contains the "instance a", which I get it from the client.
The client has either the hashCode or the string-version of the instance!
So I get only the hashCode or the string-version of "instance a".

Which version should I use:

// client gives me the instance a in form of the hashCode
for(O _o: list){ if(_o.hashCode.equals(a)){ return _o; } }

// client gives me the instance a in form of an identifiable string-version of a:
for(O _o: list){ if(_o.toString.equals(a)){ return _o; } }

So which version should I use? Both actually works, but I am not sure, if I can rely on the hashCode everytime. Which is better?

Oh, so should I do something like that:


var myModule= (function() { Submodule: { do = function(){ console.log("do called"); } })();

Is this better ?

Thanks it works, but I how do I solve that, when using module-pattern:

var myModule= (function() { var Submodule= { do: function(){ console.log("do called"); } })();

I want to call Submodule by string:

Something like myModule['Submodule'].do();

does not work.

I have a common js-object:

var TEST = { a: "1", b: "2" }

I know, I can call property a via TEST.a or via TEST['a'].

I want to do something like this:

['TEST'].a

But it does not work. How can I do that? Should I use eval or call() or something?

I was so blind! You are right!

I am using jsf with templating and had something like this <ui:remove>

within the tags which was called by javascript.

So that was the reason.

Thanks !!

I have a self invoking function with a window.onload in it. But the window.onload is not really called after windows is loaded. Often, myBtn returns null as the chrome-debugger says

"Uncaught TypeError: Cannot set property 'onclick' of null".

Why is that so? How can I solve that?

(function() { window.onload = function() { console.log("window.onload is called"); var btn= document.getElementById('myBtn'); btn.onclick = function() { ... }; }; })();



Using jquery and this script returns the same error:

(function() { $(function() { console.log("window.onload is called"); var btn= document.getElementById('myBtn'); btn.onclick = function() { ... }); }; })();




I have put the script into the head-element.

I know, that document.ready will run immediately after DOM is built.
Self-invoking functions will run instantly - but window-onload should, normally should run after dom is built.
But this is not the case. Why?

I added the parent-property (the string-identifier of the parent component in which my component is put):

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core" xmlns:cc="http://java.sun.com/jsf/composite"> <!-- INTERFACE --> <cc:interface> <cc:attribute name="id" /> <cc:attribute name="parentId" /> <cc:attribute name="value" /> <cc:attribute name="items" /> </cc:interface> <!-- IMPLEMENTATION --> <cc:implementation> <div> <h:selectOneMenu id="#{cc.attrs.id}" value="#{cc.attrs.value}" valueChangeListener="#{bean.onChange}"> <f:selectItems value="#{cc.attrs.items}" var="o" itemLabel="#{o}" itemValue="#{o}"/> <f:ajax render="#{cc.attrs.parentId}" /> </h:selectOneMenu> </div> </cc:implementation>

The use of my component:

<h:form preprendId="false"> <h:panelGroup id="client-view" layout="block"> <res:test id="test-id" parentId="client-view" value="#{bean.value}" items="#{bean.items}"/> </h:panelGroup> </h:form>

now returns the following error:

java.lang.IllegalArgumentException: java.lang.ClassCastException@2b4193b3
at sun.reflect.GeneratedMethodAccessor213.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at javax.faces.component.UIComponentBase$AttributesMap.put(UIComponentBase.java:2399)
at javax.faces.component.UIComponentBase$AttributesMap.put(UIComponentBase.java:2283)
at com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler$CompositeComponentRule$LiteralAttributeMetadata.applyMetadata(CompositeComponentTagHandler.java:577)
at com.sun.faces.facelets.tag.MetadataImpl.applyMetadata(MetadataImpl.java:81)

Unfortunately, ":client-view" does also not work:

<f:ajax> contains an unknown id ':client-view' - cannot locate it in the context of the component test-id.

When I look at the client-code, that the component has indeed the "client-view" as ID. (no ":my-form:client-view", as I wrapped the component with <h:form id="my-form" prependId="false">).

Why does my JSF-component not find the ID of its parent?

I want to organize/structure/encapsulate all my jquery javascript code:

I have a file "mypage_version1.js" with the following content (VERSION 1):

$(function() { // tabs for view a setupTabs('#idViewA', '#contentA'); // tabs for view b setupTabs('#idViewB', '#contentB'); }); var setupTabs = function(parent, content){ $(parent).on('click', nav, function() { ... return false; }); };

How can I organize it better?

Does the file "mypage_version2.js" with the following content (VERSION 2) structures the code better than "VERSION 1"?:

// create a global namespace var myview= {}; $(function() { var tabsA = new Tabs('#idViewA', '#contentA'); tabsA .create(); var tabsB = new Tabs('#idViewB', '#contentB'); tabsB .create(); }); function Tabs(parent, content) { // properties this.parent = parent; this.content= content; // method Tabs.prototype.create = function() { // I cannot use "this.parent", as it is undefined when calling the jquery-function, so I have to use "parent" which is assigned $(parent).on('click', content, function() { ... return false; }); }; ; };

I am in doubt, which version is better (both works).

Version 1 is shorter, but cluttered within the file.

What is best practice?

I have a component called "test":

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core" xmlns:cc="http://java.sun.com/jsf/composite"> <!-- INTERFACE --> <cc:interface> <cc:attribute name="id" /> <cc:attribute name="value" /> <cc:attribute name="items" /> </cc:interface> <!-- IMPLEMENTATION --> <cc:implementation> <div> <h:selectOneMenu id="#{cc.attrs.id}" value="#{cc.attrs.value}" valueChangeListener="#{bean.onChange}"> <f:selectItems value="#{cc.attrs.items}" var="o" itemLabel="#{o}" itemValue="#{o}"/> <f:ajax render="#{cc.attrs.parent}" /> </h:selectOneMenu> </div> </cc:implementation>

and the "view.xhtml" which uses the component "test":

<h:panelGroup id="client-view" layout="block"> <res:test id="test-id" parent="client-view" value="#{bean.value}" items="#{bean.items}"/> </h:panelGroup>


When rendering "view.xhtml", then I get the following error:

f:ajax> contains an unknown id 'client-view' - cannot locate it in the context of the component test-id.


How can I solve that?

(Besides, when using <f:ajax render="@form" /> within the component-component all works, but I want to assign a ID to limit the rendering.)