zk - java textbox validation before fileupload -

i have textbox , button upload = true attribute component in zk framework , control textbox value, if empty or not, before upload dialog pops up. tried onchange event on textbox disable , enable button according value problem button not enabled/disabled before clicking somewhere else. if write text in textbox , after click on button, still remains diabled. after second click gets activated.

you should use onchanging instead of onchange. also, zk-side solution working correctly zk + java side solution not working want.

zk-side solution ( working )

<zk>   <textbox>     <attribute name="onchanging">       if ( event.getvalue().length() > 0 )         but.setdisabled( false );       else         but.setdisabled( true );     </attribute>   </textbox>   <button id="but" disabled="true" upload="true,maxsize=300" label="up" /> </zk> 

zk + java solution ( not working properly )

zk

<window title="hello world!!" border="normal" width="200px" apply="com.uploadfile">  <textbox id="value" />  <button id="but" disabled="true" upload="true,maxsize=300" label="up" />  </window> 

java

public class uploadfile extends genericforwardcomposer<window> {      private static final long serialversionuid = 1l;      private textbox value;     private button but;      public void onchanging$value() {         if ( value.getvalue().length() > 0 )             but.setdisabled( false );           else             but.setdisabled( true );     }      public void onclick$but() {         alert(value.getvalue());     } }