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在Java中使用< >和不使用它有什么区别?[副本]

java

Arezoo Bagherzadi · 技术社区 · 6 年前

这个问题已经有了答案:

What is a raw type and why shouldn't we use it? 15个答案

我有一段这样的代码:

@RequestMapping(value = "/find/{id}")
@GetMapping
public ResponseEntity<QuestionModel> find(@PathVariable("id") Long id) {
    Question question = questionService.find(id);
    QuestionModel questionModel = new QuestionModel(question);
    **return new ResponseEntity<>(questionModel, HttpStatus.OK);**
}

我想知道这两者之间有什么区别:

@RequestMapping(value = "/find/{id}")
@GetMapping
public ResponseEntity<QuestionModel> find(@PathVariable("id") Long id) {
    Question question = questionService.find(id);
    QuestionModel questionModel = new QuestionModel(question);
    **return new ResponseEntity(questionModel, HttpStatus.OK);**
}

1 回复 | 直到 6 年前

Zabuzard Louis-Philippe Lebouthillier 6 年前

<...> < What is a raw type and why shouldn't we use it?

<> <Foo> var What is the point of the diamond operator in Java 7?

// Are the same
List<Integer> values = new ArrayList<Integer>();
List<Integer> values = new ArrayList<>();

// Raw types, don't use if > Java 5
List values = new ArrayList();
// Assigning a raw-type to a generic variable, mixing both, don't use
List<Integer> values = new ArrayList();

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