泛型

ARules、BRules、CRules extends AbstractRules

List<ARules> rules = xxx;
Map<String, List<ARules>> rulesGroupByStrategy = classifyByStrategyId(rules);
private <T extends AbstractRules> Map<String, List<T>> classifyByStrategyId(List<T> rules) {
    Map<String, List<T>> mappings = new HashMap<>(16);
    for (T rule : rules) {
        String strategyId = rule.getStrategyId();
        mappings.computeIfAbsent(strategyId, k -> new LinkedList<>());
        mappings.get(strategyId).add(rule);
    }
    return mappings;
}