我正在尝试获取 String ArrayList 的重复值的计数，我已经完成了任务，但还没有完全完成。我能够得到 counts重复项 elements我的arrayList ，但问题是order的arrayList当我得到occurrences时破坏的elements
这是我的code :
Map<String, Integer> counts = new HashMap<String, Integer>();
for (String str : t.courseName) {
if (counts.containsKey(str)) {
counts.put(str, counts.get(str) + 1);
} else {
counts.put(str, 1);
}
}
for (Map.Entry<String, Integer> entry : counts.entrySet()) {
System.out.println(entry.getKey() + " = " + entry.getValue());
}
此代码可以很好地获取 occurrences但请注意，此代码会破坏 order 。我想要的是 order也不应该被破坏。
最佳答案
使用LinkedHashMap而不是 HashMap 来保留插入顺序
A LinkedHashMap is a combination of hash table and linked list. It has a predictable iteration order (a la linked list), yet the retrieval speed is that of a HashMap. The order of the iteration is determined by the insertion order, so you will get the key/values back in the order that they were added to this Map.
关于java - Java中获取arrayList中重复值的计数而不影响arrayList的顺序，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41380274/