我們如何在沒有 lambda 表達式和流的情況下轉換以下代碼？

Question

如何在不使用 Java 中的 lambda 表達式和流的情況下將以下代碼轉換為每個循環？

@Override
protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException ex,
        HttpHeaders headers, HttpStatus status, WebRequest request) {
    List<String> validationList = ex.getBindingResult().getFieldErrors().stream()
            .map(fieldError -> fieldError.getDefaultMessage()).collect(Collectors.toList());
    return new ResponseEntity<>(validationList, status);
}

Answer 1

@Override
protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException ex,
                HttpHeaders headers, HttpStatus status, WebRequest request) {
    List<String> validationList = ex.getBindingResult().getFieldErrors().stream()
            .map(fieldError -> fieldError.getDefaultMessage()).collect(Collectors.toList());
    return new ResponseEntity<>(validationList, status);
}

它將轉換為以下代碼：

@Override
protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException ex,
                HttpHeaders headers, 
                HttpStatus status, 
                WebRequest request) {
    List<String> validationList = new ArrayList<>();
    List<FieldError> validationErrorList = ex.getBindingResult().getFieldErrors();
    for(FieldError fieldError: validationErrorList) {
        validationList.add(fieldError.getDefaultMessage());
    }
    return new ResponseEntity<>(validationList, status);
}