My Custom Validator is not working as i want

[Yahya Arshad]

public MobileValidator(){
		
	}
   
	public void validate(FacesContext facesContext, 
            UIComponent uIComponent, Object object) throws ValidatorException {
        
    	
    	String enteredMobile = (String)object;     // Converts Entered Mobile number to String
        
             boolean matchFound = false;          
       
        if( (enteredMobile.length()==12) && enteredMobile.charAt(4)=='-' )        // if mobile number entered in jsp page is of lenght 12 
                                                                                                                 // and have '-' charachter at location 4

        {
        	for(int i=0;i<enteredMobile.length(); i++)
        	{
        		if(i!=4 )
        		{
        			if(Character.isDigit(enteredMobile.charAt(i)))    // to varify that each one is digit except location 4
        					    {
        						matchFound=true;
        					   	}
        					
        			
        			
        		}
        		
        		
        	  }
        	
        	
        }
                   
        
        if (!matchFound) {
            FacesMessage message = new FacesMessage();
            message.setDetail("Please enter in form (xxxx-xxxxxxx)");
          
            message.setSeverity(FacesMessage.SEVERITY_ERROR);
            throw new ValidatorException(message);
        }
    }
    
}

i have made a custom validator for mobile number that entered mobile number should not greater than 12 and must have - charachter at location 4 (0321-3809083 for example) but there when i run it see only length and '-' charachter at location 4 but if it contatins other than digit on other place it take it ok

please help me to findout a bug

also if any one can give me link t o findout the Pattern way...
please reply thanks in advance