如何检查 JAVA 中对象的变量是 Empty 还是 NULL？

Question

如何检查 variables of Objects 是 JAVA 中的 empty or NULL？

Employee employee = repository.getEmployee(id).orElseGet(null);
if (employee == null) {
   employee = new Employee();
   employee.id(1);
   employee.name("Thirumal");
   employee.mobile("+91-8973-697-871");
   repository.save(employee);
}

我试图创建一个对象 new Employee()

而不是 NULL

Employee employee = repository.getEmployee(id).orElseGet(new Employee());
if (employee.isEmpty()) { //--------- How to do ????????
   employee = new Employee();
   employee.id(1);
   employee.name("Thirumal");
   employee.mobile("+91-8973-697-871");
   repository.save(employee);
}

如何检查 member of objects 是 empty/NULL？

Answer 1

只需将 isEmpty 方法添加到 Employee class 并在那里实现它，或者使用 null object pattern 而不是 new Employee().

至于您在代码中实际尝试做的事情，我建议改为这样做：

Employee employee = repository.getEmployee(id).orElseGet(() -> {
   Employee emp = new Employee();
   emp.id(1);
   emp.name("Thirumal");
   emp.mobile("+91-8973-697-871");
   return repository.save(emp);
});

如何检查 JAVA 中对象的变量是 Empty 还是 NULL？

How to check the variables of an Object are Empty or NULL in JAVA?

java

null

initialization

isnullorempty

java-11