关于save的判断
为什么repository.put()的值为空就表明保存成功啊
夜樱奏
2018-11-28
1 回答
参照源码的相关说明
/** * @return the previous value associated with <tt>key</tt>, or * <tt>null</tt> if there was no mapping for <tt>key</tt>. * (A <tt>null</tt> return can also indicate that the map * previously associated <tt>null</tt> with <tt>key</tt>, * if the implementation supports <tt>null</tt> values.) */
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