Java 如何检查 ArrayList 是否包含 2 个值？
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How to Check if an ArrayList Contain 2 values?
提问by Yehia Awad
is there any way to check if a collection contain a value or more with better performance than looping twice with contains?
有什么方法可以检查集合是否包含一个或多个值，其性能比使用包含循环两次更好？
in other meaning something that would look like this
换句话说，看起来像这样的东西
person.contains("Joe" || "Jasha");
采纳答案by Bohemian
The implementation of ArrayList.contains()loops through every element and does an equals()test, so calling .contains()twice is inefficient.
实现ArrayList.contains()遍历每个元素并进行equals()测试，因此调用.contains()两次效率低下。
You could write your own loop that check both at once using a compiled regex Patternthat looks for either name at the same time:
您可以编写自己的循环，使用同时查找任一名称的已编译正则表达式模式一次检查两者：
Pattern p = Pattern.compile("Joe|Jasha");
boolean found = false;
for (String s : person) {
if (p.matcher(s).find()) {
found = true;
break;
}
}
回答by Suresh Atta
contains takes only one param
contains 只需要一个参数
if(person.contains("Joe") || person.contains("Jasha")){
// do something
}
If you are worrying about Nnumber of elements
如果您担心N元素的数量
String[] items ={"Joe","jon","And So On".....};
for (String item : items ) {
if (person.contains(item)) {
//found
break;
}
}
Edit:
编辑：
That ||is most helpful in your case, since you have the benefit of Short-circuit_evaluation
这||对您的情况最有帮助，因为您受益于Short-circuit_evaluation
The second argument is only executed or evaluated if the first argument does not suffice to determine the value of the expression:
仅当第一个参数不足以确定表达式的值时，才执行或评估第二个参数：
回答by Shiju K Babu
You have to search each string.
您必须搜索每个字符串。
UPDATED
更新
List list=new ArrayList();
list.add("Joe");
list.add("Jasha");
if(person.containsAll(list))
{
//do something
}
回答by Infinite Recursion
You can also use regex as follows:
您还可以按如下方式使用正则表达式：
person.toString().matches(".*\b(Joe|Jasha)\b.*");
You will get a boolean value indicating whether it is present or not.
您将获得一个布尔值，指示它是否存在。
回答by Chandrayya G K
Simply use Arrays class
只需使用 Arrays 类
person.containsAll(Arrays.asList("Jasha","Joe"));
回答by awwsmm
You can also do
你也可以这样做
String person1 = "Joe Smith"; // contains "Joe"
String person2 = "Jasha Thompson"; // contains "Jasha"
String person3 = "Jasha Joesephson"; // contains "Joe" and "Jasha"
String person4 = "Steve Smith"; // contains neither
public boolean containsJoeOrJasha(String stringToCheck) {
return !Collections.disjoint(
Arrays.asList(stringToCheck.split(" ")),
Arrays.asList("Joe", "Jasha"));
}
Collections.disjoint returns true if the two collections are disjoint, meaning that they have no elements in common. So...
如果两个集合不相交，则 Collections.disjoint 返回 true ，这意味着它们没有共同的元素。所以...
jshell> containsJoeOrJasha(person1)
==> true
jshell> containsJoeOrJasha(person2)
==> true
jshell> containsJoeOrJasha(person3)
==> true
jshell> containsJoeOrJasha(person4)
==> false
