java 将整数集转换为 int[] 数组的问题
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Problems converting Set of Integers to int[] array
提问by L-Samuels
I have no problems converting a Set of Strings to a string[] array, but I'm having problems doing so with converting a Set of Integer to an int[] array. How can I convert the Integers to its primitive?
我在将一组字符串转换为 string[] 数组时没有问题，但是在将一组整数转换为 int[] 数组时遇到了问题。如何将整数转换为其原始类型？
I cannot seem to find any related questions. Any quick suggestions that can help?
我似乎找不到任何相关的问题。任何可以提供帮助的快速建议？
Sometimes, autoboxing cannot be used, as in the case of arrays. I don't think an array of integers will automatically be converted to an array of ints.
有时，不能使用自动装箱，例如数组。我认为整数数组不会自动转换为整数数组。
回答by Thomas
string[]doesn't exist, I guess you mean String[].
string[]不存在，我猜你的意思是String[]。
For converting a Set<Integer>to int[]you'd have to iterate over the set manually.
Set<Integer>要将a 转换为int[]您必须手动迭代该集合。
Like this:
像这样：
Set<Integer> set = ...;
int[] arr = new int[set.size()];
int index = 0;
for( Integer i : set ) {
arr[index++] = i; //note the autounboxing here
}
Note that sets don't have any particular order, if the order is important, you'd need to use a SortedSet.
请注意，集合没有任何特定顺序，如果顺序很重要，则需要使用 SortedSet.
回答by Kevin Bourrillion
This is why Guava has an Ints.toArray(Collection<Integer>)method, returning int[].
这就是为什么 Guava 有一个Ints.toArray(Collection<Integer>)方法，返回int[].
回答by linh nguyenvan
With java 8:
使用 Java 8：
Set<Integer> set = new HashSet<>();
// TODO: Add implement for set
int[] array = set.stream().mapToInt(Integer::intValue).toArray();
回答by Péter T?r?k
I guess the problem is that Set<Integer>.toArrayconverts to Integer[], rather than int[]. So you have no simple way: you need to iterate through the set manually and add its elements to the int array. Converting an individual Integerto intis handled by autoboxing in Java 5 and above.
我想问题是Set<Integer>.toArray转换为Integer[], 而不是int[]. 所以你没有简单的方法：你需要手动遍历集合并将其元素添加到 int 数组中。转换的个体Integer，以int通过在Java 5及更高自动装箱处理。
回答by filip-fku
This should work, assuming auto unboxing!
这应该有效，假设自动拆箱！
Set<Integer> myIntegers; // your set
int[] ints = new int[myIntegers.size()];
int index = 0;
for(Integer i : myIntegers){
ints[index++] = i;
}
回答by MozenRath
you can call the
你可以打电话给
Integer.intValue();
function...
功能...
lemme know more specifics of what you need :)
让我知道你需要什么的更多细节:)
回答by Cygnusx1
If you use Java 5+ Autoboxing should take care of this...!
如果您使用 Java 5+ 自动装箱应该注意这一点...！
What error do you get?
你得到什么错误？
edit: ok i see..
编辑：好的，我明白了..
Like other said:
就像其他人说的：
loop on your Set and just put the Integer inside the int[], autoboxing should convert it.
在你的 Set 上循环并将整数放在 int[] 中，自动装箱应该转换它。
