有人可以用Java解释这个方法吗：

Question

This is in a class called a resource. I'm not sure what it does and need help understanding it. trainingDTO has a UUID and an Item.

if (this.toDoList.addItem(trainingDto.getItem())) {
          return Response.status(200).build();
          TrainingDTO returnDTO = new TrainingDTO();
          returnDTO.setItem(trainingDto.getItem());
          UUID uuid = toDoList.findUUIDByValue(trainingDto.getItem());
          returnDTO.setUUID(uuid.toString());
          return Response.ok(returnDTO).build();
        }

Answer 1

Explaining this block is a little difficult for two reasons. 1.) you didn't give us much context: ie we don't have the method containing the block, or any other surrounding code. 2.) this method has some odd code. That being said, let's go through line by line:

if (this.toDoList.addItem(trainingDto.getItem())) {

This if condition is a little complicated because addItem() obviously does more than just return a boolean. Generally, this is considered bad form (methods should do just one thing, and adding to a list and returning a boolean are two things). But that's what it does: it adds (or tries to add) to toDoList , and returns a boolean.

    return Response.status(200).build();

As written, this will always be the last line executed. This return statement will always cause the function to return, and it means the lines below will not be executed. But if it didn't, then the lines below would...

    TrainingDTO returnDTO = new TrainingDTO();

Create a new object of type TrainingDTO

    returnDTO.setItem(trainingDto.getItem());

Set a field of that object based on a field of an existing object (the same one referenced in the if condition)

    UUID uuid = toDoList.findUUIDByValue(trainingDto.getItem());

Find the value of something called a UUID for the object from the if condition

    returnDTO.setUUID(uuid.toString());

Use the UUID value above to set the UUID value for our new object

    return Response.ok(returnDTO).build();

Make a Response using the new object, and call its build() method, then return that result

}