RegexpValidator不會阻止空字符串

Question

如果我沒有在文本字段中插入任​​何內容（內容將只是0-8之間的數字），表單生成廣告異常

我有驗證表單vaadin的問題

Validator onlyNumber= new RegexpValidator("[0-8]","only number between 0 and 8") { 
        @Override 
        protected boolean isValidString(String value) { 
         if (value == "" || value.equals("") || value.isEmpty()) 
          return false; 
         else 
          return value.matches("[0-8]"); 
        } 
       }; 

此異常

Exception 

com.vaadin.data.Property$ConversionException: java.lang.reflect.InvocationTargetException 

at com.vaadin.data.util.MethodProperty.convertValue(MethodProperty.java:695) 

at com.vaadin.data.util.MethodProperty.setValue(MethodProperty.java:664) 

at com.vaadin.ui.AbstractField.commit(AbstractField.java:268) 

at com.vaadin.ui.Form.commit(Form.java:339) 

at it.ads.pta.web.planning.TabellaDinamica.commitButtonClick(TabellaDinamica.java:574) 

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) 

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 

at java.lang.reflect.Method.invoke(Method.java:597) 

at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:520) 

at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164) 

at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1219) 

at com.vaadin.ui.Button.fireClick(Button.java:567) 

at com.vaadin.ui.Button.changeVariables(Button.java:223) 

at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.changeVariables(AbstractCommunicationManager.java:1481) 

at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariableBurst(AbstractCommunicationManager.java:1425) 

at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariables(AbstractCommunicationManager.java:1350) 

at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleUidlRequest(AbstractCommunicationManager.java:780) 

at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:325) 

at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:501) 

at it.ads.pta.web.servlet.SpringApplicationServlet.service(SpringApplicationServlet.java:95) 

at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) 

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) 

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) 

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) 

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) 

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) 

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947) 

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) 

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009) 

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) 

at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) 

at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) 

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) 

at java.lang.Thread.run(Thread.java:662) 

Caused by: java.lang.reflect.InvocationTargetException 

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) 

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) 

at java.lang.reflect.Constructor.newInstance(Constructor.java:513) 

at com.vaadin.data.util.MethodProperty.convertValue(MethodProperty.java:692) 

... 37 more 

Caused by: java.lang.NumberFormatException: For input string: "" 

at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48) 

at java.lang.Integer.parseInt(Integer.java:470) 

at java.lang.Integer.<init>(Integer.java:660) 

... 42 more 

Answer 1

@Override 
    protected boolean isValidString(String value) { 
     if (value==null || value.isEmpty() || value.trim().equals("")) 
       return false; 
     else 
       return value.trim().matches("[0-8]"); 
    } 

Answer 2

也許改變正則表達式[0-8]？用問號來使它可選會使它更好。你不需要以這種方式擴展驗證器。