private void initPriority()
    {
    	priority = 0;
    	
    	if(type == ExpItemType.OPERATOR)
    	{
    		String op = value.toString();
    		
    		if(op.equals("+") || op.equals("-")){
    			priority = 1;
    		}
    		
    		if(op.equals("*") || op.equals("/")){
    			priority = 2;
    		}
    	}
    }