处理 Lambda 表达式中的空值

Question

I am trying to iterate List of Map using lambda expression and while iterating I have to set the values in one POJO using field setter method. The problem comes when there are null values in List of Map (in particular map field null should be handled). I tried so many things to handle NullPointerException .

Employee employee = new Employee();

employee.setEmployeeName(result.getOrDefault("employeeName", "").toString());

employee.setEmployeeName(!StringUtils.isEmpty(result.get("employeeName").toString()) ? result.get("employeeName").toString() : " "); 
// when i am using this solution it is not giving null pointer exception 
// but if the value is null then it is returning "null" value it means 
// null as a string which shouldn't be the expected output. 

employee.setEmployeeName(String.valueOf(result.get("employeeName").equals("null") ? "" : result.get("employeeName")));

List<Map<String,Object>> r1 = new ArrayList<Map<String,Object>>();
    response.forEach(result -> { 
        employee.setEmployeeName(result.getOrDefault("employeeName", "").toString());

    })

Answer 1

问题已解决，我使用了 Optional，如下所示。

Optional.ofNullable(result.get("employeeName")).orElse(" ").toString()