Java 如何计算arrayList中出现的相同值
下面是我想查找多次出现的动物名称的代码片段 我已经编写了比较列表索引的代码,但无法理解如何比较名称并计算每个名称的出现次数Java 如何计算arrayList中出现的相同值,java,arraylist,count,Java,Arraylist,Count,下面是我想查找多次出现的动物名称的代码片段 我已经编写了比较列表索引的代码,但无法理解如何比较名称并计算每个名称的出现次数 List<Animals> animalList= new ArrayList<Animals>(); try { CallableStatement stmt = conn.prepareCall(callProcedure, ResultSet.TYPE_SCROLL_INSENSITIV
List<Animals> animalList= new ArrayList<Animals>();
try {
CallableStatement stmt = conn.prepareCall(callProcedure, ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
boolean results = stmt.execute();
if (results) {
ResultSet rs = stmt.getResultSet();
int count = 0;
while (rs.next()) {
Animals animal = new Animals();
animal.setAnimalName(rs.getString("animal_name"));
animal.setAge(rs.getString("age"));
animal.setHealth(rs.getString("health"));
animalList.add(animal);
count++;
}
}
int nbOccurences = 1;
for (int i = 0, length = animalList.size(); i < length; i++) {
if (i < length - 1) {
if (animalList.get(i) == animalList.get(i+1)) {
nbOccurences++;
}
} else {
System.out.println( animalList.get(i) + " occurs " + nbOccurences
+ " time(s)"); //end of array
}
if (i < length - 1 && animalList.get(i) != animalList.get(i+1)) {
System.out.println( animalList.get(i) + " occurs " + nbOccurences
+ " time(s)"); //moving to new element in array
nbOccurences = i;
}
}
} catch (SQLException sqlE) {
sqlE.printStackTrace();
}
return animalList;
IMHO最简单的解决方案是将动物列表按名称和数量分组:
Map<String, Long> nameCount =
animalList.stream()
.collect(Collectors.groupingBy(Animal::getName,
Collectors.counting()));
IMHO最简单的解决方案是将动物列表按名称和数量分组:
Map<String, Long> nameCount =
animalList.stream()
.collect(Collectors.groupingBy(Animal::getName,
Collectors.counting()));
首先,您应该记住Java中==和equals之间的差异,然后不应该在animalsList.getx上进行比较,而应该在animalsList.getx.getAnimalName之类的东西上进行比较,因为您希望找到多次出现的动物名称。首先,您应该记住Java中==和equals之间的差异,然后,您不应该在animallist.getx上进行比较,而应该在animallist.getx.getAnimalName上进行比较,因为您希望找到多次出现的动物名称。感谢您提供的解决方案。!!谢谢你的解决方案。!!