ListView自定义适配器Try-Catch块内TextView初始化后不显示数据求助

核心问题：TextView赋值逻辑错误 #

你代码里最直接的bug是没有调用TextView的setText()方法，而是直接给ViewHolder里的TextView变量重新赋值，导致原来的控件引用被覆盖，自然不会显示任何内容。

错误写法：

viewHolder.ps_m = setPatientStatus(followupModel.PtStatus);

正确写法：

viewHolder.ps_m.setText(setPatientStatus(followupModel.PtStatus));

所有类似viewHolder.xxx = setPatientStatus(...)的代码都要改成调用setText()的形式。

优化方案：避免UI线程操作数据库 #

getView运行在UI线程，同步调用dbHelper.GetFollowupData()会阻塞UI，造成列表滑动卡顿甚至ANR，必须改成异步加载：

1. 预加载数据到数据源 #

在Adapter初始化时，通过异步任务一次性加载所有随访数据，给AdmissionModel添加followupData字段缓存结果，getView里直接使用缓存好的数据，无需实时查询数据库。

2. 单条数据异步加载（无法预加载时） #

如果必须在getView中加载单条数据，用AsyncTask或Coroutine实现异步查询（Java推荐AsyncTask，Kotlin推荐Coroutine）：

private class LoadFollowupTask extends AsyncTask<String, Void, List<FollowupModel>> {
    private AdmissionModel admissionModel;
    private AdmissionViewHolder viewHolder;

    public LoadFollowupTask(AdmissionModel model, AdmissionViewHolder holder) {
        this.admissionModel = model;
        this.viewHolder = holder;
    }

    @Override
    protected List<FollowupModel> doInBackground(String... params) {
        String previousDay = params[0];
        String toDay = params[1];
        return dbHelper.GetFollowupData(admissionModel.NtfSL, previousDay, toDay);
    }

    @Override
    protected void onPostExecute(List<FollowupModel> followupModels) {
        super.onPostExecute(followupModels);
        // 清空旧数据
        viewHolder.ps_m.setText("");
        viewHolder.ps_e.setText("");
        viewHolder.ps_n.setText("");
        viewHolder.ts_m.setText("");
        viewHolder.ts_e.setText("");
        viewHolder.ts_n.setText("");

        if(followupModels.size()>0){
            Map<String, List<FollowupModel>> groupByDateList = Stream.of(followupModels).collect(
                    Collectors.groupingBy(e->e.FollowupDateyyyMMdd));

            for (String dataKey : groupByDateList.keySet()){
                if(dataKey.equals(params[0])){
                    for (FollowupModel followupModel : groupByDateList.get(dataKey)){
                        if(followupModel.Type == 1){
                            viewHolder.ps_m.setText(setPatientStatus(followupModel.PtStatus));
                        }else if(followupModel.Type == 2){
                            viewHolder.ps_e.setText(setPatientStatus(followupModel.PtStatus));
                        }else if(followupModel.Type == 3){
                            viewHolder.ps_n.setText(setPatientStatus(followupModel.PtStatus));
                        }
                    }
                }else if(dataKey.equals(params[1])){
                    for (FollowupModel followupModel : groupByDateList.get(dataKey)){
                        if(followupModel.Type == 1){
                            viewHolder.ts_m.setText(setPatientStatus(followupModel.PtStatus));
                        }else if(followupModel.Type == 2){
                            viewHolder.ts_e.setText(setPatientStatus(followupModel.PtStatus));
                        }else if(followupModel.Type == 3){
                            viewHolder.ts_n.setText(setPatientStatus(followupModel.PtStatus));
                        }
                    }
                }
            }
        }
    }
}

在getView中启动任务：

try {
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
    Date date = new Date();
    String toDay = formatter.format(date);

    Calendar cal = Calendar.getInstance();
    cal.add(Calendar.DATE, -1);
    String previousDay = formatter.format(cal.getTime());

    new LoadFollowupTask(admissionModel, viewHolder).execute(previousDay, toDay);
} catch (Exception e) {
    e.printStackTrace();
}

其他优化点 #

• 处理数据为空的情况：在设置数据前清空TextView，避免ListView复用控件时显示旧数据。
• 线程安全的日期格式化：SimpleDateFormat线程不安全，用ThreadLocal包装：

private static ThreadLocal<SimpleDateFormat> dateFormatter = new ThreadLocal<SimpleDateFormat>() {
    @Override
    protected SimpleDateFormat initialValue() {
        return new SimpleDateFormat("yyyy-MM-dd");
    }
};
// 使用时
String toDay = dateFormatter.get().format(date);

• 简化数据分组逻辑：用双层Map直接存储日期+类型对应的状态，避免嵌套遍历：

Map<String, Map<Integer, String>> statusMap = new HashMap<>();
for(FollowupModel model : followupModelList) {
    statusMap.computeIfAbsent(model.FollowupDateyyyMMdd, k -> new HashMap<>())
             .put(model.Type, setPatientStatus(model.PtStatus));
}
// 直接取值设置
viewHolder.ps_m.setText(statusMap.getOrDefault(previousDay, new HashMap<>()).getOrDefault(1, ""));

修复后的核心代码片段 #

try {
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
    Date date = new Date();
    String toDay = formatter.format(date);

    Calendar cal = Calendar.getInstance();
    cal.add(Calendar.DATE, -1);
    String previousDay = formatter.format(cal.getTime());

    // 清空旧数据
    viewHolder.ps_m.setText("");
    viewHolder.ps_e.setText("");
    viewHolder.ps_n.setText("");
    viewHolder.ts_m.setText("");
    viewHolder.ts_e.setText("");
    viewHolder.ts_n.setText("");

    List<FollowupModel> followupModelList = dbHelper.GetFollowupData(admissionModel.NtfSL,previousDay,toDay);

    if(followupModelList.size()>0){
        Map<String, List<FollowupModel>> groupByDateList = Stream.of(followupModelList).collect(
                Collectors.groupingBy(e->e.FollowupDateyyyMMdd));

        for (String dataKey : groupByDateList.keySet()){
            if(dataKey.equals(previousDay)){
                for (FollowupModel followupModel : groupByDateList.get(dataKey)){
                    if(followupModel.Type == 1){
                        viewHolder.ps_m.setText(setPatientStatus(followupModel.PtStatus));
                    }else if(followupModel.Type == 2){
                        viewHolder.ps_e.setText(setPatientStatus(followupModel.PtStatus));
                    }else if(followupModel.Type == 3){
                        viewHolder.ps_n.setText(setPatientStatus(followupModel.PtStatus));
                    }
                }
            }else if(dataKey.equals(toDay)){
                for (FollowupModel followupModel : groupByDateList.get(dataKey)){
                    if(followupModel.Type == 1){
                        viewHolder.ts_m.setText(setPatientStatus(followupModel.PtStatus));
                    }else if(followupModel.Type == 2){
                        viewHolder.ts_e.setText(setPatientStatus(followupModel.PtStatus));
                    }else if(followupModel.Type == 3){
                        viewHolder.ts_n.setText(setPatientStatus(followupModel.PtStatus));
                    }
                }
            }
        }
    }

} catch (ParseException e) {
    e.printStackTrace();
}

内容的提问来源于stack exchange，提问作者Hossain Kabir