java – 返回不可变列表

但是,如果用户对答案进行了更改,我希望用户调用更新方法,以便我可以进行其他验证等.现在,如果用户获得答案列表,他仍然可以通过说问题更改答案. ().get(0).setDescription(“BLAH BLAH”).

所以我想回复每个答案的副本,让用户改变这个,他必须将它合并/更新回问题.通过这种方法,我可以确保答案是有效的,但答案的equals方法是基于描述和正确的字段而不是id字段,因为我使用JPA.如果用户使用此方法更改答案,则更新方法将找不到答案,因为说明字段已更改且不再相等,因此在列表中找不到它.

有什么建议吗？

public void updateAnswer(Answer answer) {
    int index = answers.indexOf(answer);
    answers.set(index,answer);
}

public List<Answer> getAnswers() {
    return Collections.unmodifiableList(answers);
}


@Test
public void shouldUpdateAnswerInQuestion() {
    // Get first answer,make an update on the description
    // and then update answer on question.
    Answer answerThatWillBeUpdated = question.getAnswers().get(0);
    String updatedAnswerDescription = "Hey,it is now updated!";
    answerThatWillBeUpdated.setDescription(updatedAnswerDescription);
    question.updateAnswer(answerThatWillBeUpdated);

    // After updating check that the answer in the list is equal
    // to the answer updated.
    Answer answerFromList = question.getAnswers().get(0);

    assertEquals(answerThatWillBeUpdated,answerFromList);
}

答案类：

public class Answer {

    private long id;
    private String description;
    private Boolean correct;
    ...
}