To check the oprand or operator
using pattern in java

public boolean isOperator(String expression){
    if(expression.equals("+"))
        return true;
    return false;
}

public boolean isOperand(String expression){
    if(Pattern.matches(".*[a-zA-Z]+.*", expression))return true;
    if(Pattern.matches("^[0-9]*$",expression)) return true;
    return false;
}