String to Validate only Alpha-numeric [Regular Expression is AX ]

Following is an Example of Regular Expressions :

public boolean validate()
{
    boolean     ret;
    anytype     isValid;
    str         universalNum = CustTable_HSI_UniversalId.valueStr(); // let say "R12345678"
    // or str         universalNum = CustTable_HSI_UniversalId.text(); // let say "R12345678"

    TextBuffer  txt = new TextBuffer();

   // ret = super();

    isValid = strlen(CustTable_HSI_UniversalId.valueStr());
    if (isValid == 9)
    {
        ret = true;
    }
    else
    {
        ret = false;
        throw Global::error("Universal Id should be upto 9-character");
        }
    isValid = strFind(CustTable_HSI_UniversalId.valueStr(),'R',1,1);
    if (isValid == 1)
    {
        ret = true;
    }
    else
    {
        ret = false;
        throw Global::error("Universal Id should start wiith 'R' character");
    }
    universalNum = substr(universalNum, 2,9);
    txt.setText(universalNum);
    txt.regularExpressions(true);   // activate regular expr in search

    // Regular expression to validate only digits
    if (txt.find("^[0-9]+$"))
    {
        ret = true;
    }
    else
    {
        ret = false;
        throw Global::error("Universal Id should start wiith 'R' character and contains 0-9 consecutive numbers");
    }
    ret = super();
    return ret;
}