如何解决无法实例化HttpStatusCodeException类型的问题

HttpStatusCodeException是抽象类，Java不允许直接实例化抽象类，这就是报错的核心原因。

针对你的404 NOT FOUND场景，可改用它的具体实现子类来抛出异常，以下是两种常用写法：

方案1：使用HttpClientErrorException指定状态码 #

public CommitResponse getOneCommitInfo(String commitHash) {
    CommitResponse commit = new CommitResponse();
    for (int i = 0; i < allCommitsList.size(); i++) {
        if (((CommitResponse) allCommitsList.get(i)).getHash().equals(commitHash)) {
            commit = (CommitResponse) allCommitsList.get(i);
            return commit;
        }
    }
    throw new HttpClientErrorException(HttpStatus.NOT_FOUND);
}

方案2：使用更具体的NotFound子类（Spring 5.3+支持） #

public CommitResponse getOneCommitInfo(String commitHash) {
    CommitResponse commit = new CommitResponse();
    for (int i = 0; i < allCommitsList.size(); i++) {
        if (((CommitResponse) allCommitsList.get(i)).getHash().equals(commitHash)) {
            commit = (CommitResponse) allCommitsList.get(i);
            return commit;
        }
    }
    throw new HttpClientErrorException.NotFound();
}

额外优化：你可以把循环改成增强for循环，让代码更简洁：

public CommitResponse getOneCommitInfo(String commitHash) {
    for (Object obj : allCommitsList) {
        CommitResponse commit = (CommitResponse) obj;
        if (commit.getHash().equals(commitHash)) {
            return commit;
        }
    }
    throw new HttpClientErrorException(HttpStatus.NOT_FOUND);
}

内容的提问来源于stack exchange，提问作者Tindona