Hi All,
I am trying to create my first VF page and Controller class. I need help for further enhancements please.



I need help with the following:

1. When I hit that "Back" command button - it should redirect to a custom object page, lets say - "Employee__c".
2. Also, a custom page message should come up if any of the numbers/ text not filled (please see screenshot).

• where and how to add the following:
   if(firstNumber == '' || firstNumber == null || secondNumber == '' || secondNumber == '')
        ApexPages.addmessage(new ApexPages.message(ApexPages.severity.ERROR,'Please enter First and Second numbers'));

Please look into the below code for VF Page and Class and help me with the code. Thanks.

VF Page:
<apex:page controller="firstcls">
  <apex:form >
      <apex:pageBlock >
          <apex:pageBlockButtons location="top">
              <apex:commandButton value="Add" action="{!Addnumbers}"/>
              <apex:commandButton value="Subtract" action="{!SubtractNumbers}"/>
              <apex:commandButton value="Multiply" action="{!Multiplynumbers}"/>
              <apex:commandButton value="Divide" action="{!Dividenumbers}"/>
              <apex:commandButton value="Back" action="{!getBack}"/> //Not sure if, its right or wrong?
             
          </apex:pageBlockButtons>
          <apex:pageBlockSection >
              <apex:outputLabel value="Enter First Number"/>
              <apex:inputtext value="{!firstNumber}"/>
              <apex:outputLabel value="Enter Second Number"/>
              <apex:inputtext value="{!secondNumber}"/>
              
              <apex:outputLabel value="Result"/>
              <apex:inputText value="{!result}"/>
          </apex:pageBlockSection>
      </apex:pageBlock>
  </apex:form>
</apex:page>

CLASS:
public class firstcls {
public string firstNumber {get;set;}
    public string secondNumber {get;set;}
    public string temp;
    public string result {get;set;}
    
    public firstcls ()
    {
        //firstNumber = '0';
        //secondNumber = '0';
        result = '0';
    }
   public void Addnumbers()
    {
        
        result = string.valueof(Integer.valueof(firstNumber) + Integer.valueof(secondNumber));
    }
    
    public void SubtractNumbers()
    {
        result = string.valueof(Integer.valueof(firstNumber) - Integer.valueof(secondNumber));
    }
    public void Multiplynumbers()
    {
        
        result = string.valueof(Integer.valueof(firstNumber) * Integer.valueof(secondNumber));
    }
    public void Dividenumbers()
    {
        
        result = string.valueof(Integer.valueof(firstNumber) / Integer.valueof(secondNumber));
    }
    public PageReference getBack()
    {
    PageReference ref= new PageReference('/'+00B61000002AkLf);
    ref.setredirect(true);
    return ref;
    }
}

When I am trying to save the above class, I am getting this error-
Error: firstcls Compile Error: expecting a right parentheses, found 'B61000002AkLf' at line 39 column 47

I need guidance on this. Look forward for your helpful replies.

Thanks.