好的，这可能是一个简单的问题，但当我读到关于集合和我得到的响应时，我很困惑。
我从数据库中获取重复记录，并使用set仅存储一个条件（代码）的一条记录，以忽略剩余的重复记录。
Set<DiagnosisInfo> diagnosisInfoSet = patientDiagnosisHistoryRepository
.findBydiagnosisdesc(UUID.fromString(patientID.toUpperCase()));
我得到的回应是
"diagnosisInfo": [
{
"diagnosisCode": "T49.1X6S",
"diagnosisCodeDescription": "Underdosing of antipruritics, sequela"
},
{
"diagnosisCode": "T49.1X6S",
"diagnosisCodeDescription": "Underdosing of antipruritics, sequela"
},
{
"diagnosisCode": "T49.1X6S",
"diagnosisCodeDescription": "Underdosing of antipruritics, sequela"
},
{
"diagnosisCode": "T49.1X6S",
"diagnosisCodeDescription": "Underdosing of antipruritics, sequela"
},
{
"diagnosisCode": "V09.20",
"diagnosisCodeDescription": "Pedestrian injured in traffic accident involving unspecified motor vehicles*"
},
{
"diagnosisCode": "V09.20",
"diagnosisCodeDescription": "Pedestrian injured in traffic accident involving unspecified motor vehicles*"
},
{
"diagnosisCode": "V09.20",
"diagnosisCodeDescription": "Pedestrian injured in traffic accident involving unspecified motor vehicles*"
},
{
"diagnosisCode": "E09.8",
"diagnosisCodeDescription": "Drug or chemical induced diabetes mellitus with unspecified complications"
},
{
"diagnosisCode": "E09.8",
"diagnosisCodeDescription": "Drug or chemical induced diabetes mellitus with unspecified complications"
},
{
"diagnosisCode": "E09.8",
"diagnosisCodeDescription": "Drug or chemical induced diabetes mellitus with unspecified complications"
},
{
"diagnosisCode": "E09.8",
"diagnosisCodeDescription": "Drug or chemical induced diabetes mellitus with unspecified complications"
},
{
"diagnosisCode": "E09.8",
"diagnosisCodeDescription": "Drug or chemical induced diabetes mellitus with unspecified complications"
}
]
我们可以看到相同的诊断代码记录虽然重复，但会多次显示。我想看到的回复是
"diagnosisInfo": [
{
"diagnosisCode": "T49.1X6S",
"diagnosisCodeDescription": "Underdosing of antipruritics, sequela"
},
{
"diagnosisCode": "V09.20",
"diagnosisCodeDescription": "Pedestrian injured in traffic accident involving unspecified motor vehicles*"
},
{
"diagnosisCode": "E09.8",
"diagnosisCodeDescription": "Drug or chemical induced diabetes mellitus with unspecified complications"
}
]
一个代码的一个响应。我不知道是否必须更改我的查询，或者有关设置的内容。
答案 0 :(得分：1)
是的，这是在DiagnosisInfo不覆盖Equals和haschCode
时获得的您的Set无法知道如何检查此对象
{
"diagnosisCode": "V09.20",
"diagnosisCodeDescription": "Pedestrian injured in traffic accident involving unspecified motor vehicles*"
},
和这一个
{
"diagnosisCode": "V09.20",
"diagnosisCodeDescription": "Pedestrian injured in traffic accident involving unspecified motor vehicles*"
},
是一样的......
假设您调用的方法实现了HashSet<E>，那么spource代码：
/**
* Adds the specified element to this set if it is not already present.
* More formally, adds the specified element <tt>e</tt> to this set if
* this set contains no element <tt>e2</tt> such that
* <tt>(e==null ? e2==null : e.equals(e2))</tt>.
* If this set already contains the element, the call leaves the set
* unchanged and returns <tt>false</tt>.
*
* @param e element to be added to this set
* @return <tt>true</tt> if this set did not already contain the specified
* element
*/
public boolean add(E e) {
return map.put(e, PRESENT)==null;
}
其中map.put调用 putVal
和putval使用equals和hashcode ...哈！
final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
boolean evict) {
Node<K,V>[] tab; Node<K,V> p; int n, i;
if ((tab = table) == null || (n = tab.length) == 0)
n = (tab = resize()).length;
if ((p = tab[i = (n - 1) & hash]) == null)
tab[i] = newNode(hash, key, value, null);
else {
Node<K,V> e; K k;
if (p.hash == hash &&
((k = p.key) == key || (key != null && key.equals(k))))
e = p;
else if (p instanceof TreeNode)
e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
else {
for (int binCount = 0; ; ++binCount) {
if ((e = p.next) == null) {
p.next = newNode(hash, key, value, null);
if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
treeifyBin(tab, hash);
break;
}
if (e.hash == hash &&
((k = e.key) == key || (key != null && key.equals(k))))
break;
p = e;
}
}
if (e != null) { // existing mapping for key
V oldValue = e.value;
if (!onlyIfAbsent || oldValue == null)
e.value = value;
afterNodeAccess(e);
return oldValue;
}
}
++modCount;
if (++size > threshold)
resize();
afterNodeInsertion(evict);
return null;
}
答案 1 :(得分：1)
重点是：
我们可以看到相同的诊断代码记录虽然重复，但会多次显示。
不，他们不相同。您必须为您的类DiagnosisInfo实现正确的 equals（）和 hashCode（）方法！
为了确定两个物体是“相同的”; Set实现将使用这些对象提供的equals方法。而且最有可能的是，你要么在课堂上忘记了@Override equals（）;您提供的结果为false;即使是那些你认为“相同”的物品。
有关详细信息，请参阅here。
鉴于您的最新评论，您似乎仍然有逻辑向后。你仍然认为你“知道”哪些对象是重复的，哪些不是。但你认为不的重要性。唯一重要的是在equals（）方法中实现。 操作的结果确定对象是否相等/相似;或者如果它们不同。
所以：当你向一个类添加新字段时;并使用您的IDE重新生成这些方法，现在您对结果“不满意”;那么你的问题是你在生成过程中包含字段，你实际上认为“应该没关系”。代码执行告诉要执行的操作。
因此，真实在这里回答：