Question

I’ll preface my question by saying that I’m a beginner Java EE developer.

I wrote the following code. Why does this get the ID?

MsItemDTO msItemDTO = new MsItemDTO();
msItemDTO.setItemID(trInboundD.getItemID().getItemID());
trInboundDDTO.setItemID(msItemDTO);

Any why doesn’t get the ID (the ID = null)?

trInboundDDTO.setItemID(new MsItemDTO(trInboundD.getItemID().getItemID()));

Answer 1

MsItemDTO msItemDTO = new MsItemDTO(); 
msItemDTO.setItemID(trInboundD.getItemID().getItemID()); 
trInboundDDTO.setItemID(msItemDTO); 

We will walk through above code in detail:

1. First line, It will create an instance or object of MsItemDTO class and object name is msItemDTO.
2. Second line, We are setting Item Id to object msItemDTO that we have create in first line.
3. Third Line, we are setting the object msItemDTO to another object trInboundDDTO Item Id value.

Now we will have a look into the other code:

trInboundDDTO.setItemID(new MsItemDTO(trInboundD.getItemID().getItemID()));  

This line will create an object for MsItemDTO with some arguments called trInboundD.getItemID().getItemID(). Here you need to write a constructor to create object with this arguments. Otherwise it will not create any object and it saves Item id as null. So object is different here. And second one is that we are trying to set this different object to another object trInboundDDTO Item Id which will be conflict.

Hope this helps you 🙂