统计list集合中相同名称的元素个数

Question

一个list集合，不确定长度，其中的元素包括名称、数量两项。按名称处理，将名称相同的数量相加进行统计，但是这么写好像有问题啊，求指点

 List<QuestionTypeSettingVO> qtSettings;
QuestionTypeSettingVO qtSetting;
if (null != qtSettings && qtSettings.size() > 0) {
            for (int j = 0; j < qtSettings.size()-1; j++) {
                qtSetting = qtSettings.get(j);
                if (j > 0) sb.append(",");
                for(int k = j+1; k < qtSettings.size(); k++){
                    if(qtSetting.getQuestionType()==qtSettings.get(k).getQuestionType()){
                            sb.append("\"").append(qtSetting.getQuestionType()).append("\":")
                         .append(qtSetting.getTotalQuestionCount()+qtSettings.get(k).getTotalQuestionCount());  
                    }else{
                                    sb.append("\"").append(qtSetting.getQuestionType()).append("\":")
                                    .append(qtSetting.getTotalQuestionCount()); 
                                }
                            }
                        }
                    }

Answer 1

List qtSettings;
Map qts = new HashMap();
if (null != qtSettings && qtSettings.size() > 0) {
for (QuestionTypeSettingVO qtSetting:qtSettings) {
if(qts.containsKey(qtSetting.getQuestionType())){
qts.get(qtSetting.getQuestionType).setTotalQuestionCount(qtSetting.getTotalQuestionCount() + qts.get(qtSetting.getQuestionType).getTotalQuestionCount());
}else{
qts.put(qtSetting.getQuestionType(), qtSetting);
}
}
}
然后你要的信息都在qts里面