java 检测数组中的空引用
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Detect null reference in an array
提问by fredoverflow
I want to detect whether or not a subrange of an array contains the null reference. Somehow like this:
我想检测数组的子范围是否包含空引用。有点像这样：
public static <T> boolean containsNull
(T[] array, int fromInclusive, int toExclusive)
{
for (int i = fromInclusive; i < toExclusive; ++i)
{
if (array[i] == null) return true;
}
return false;
}
Is there a method like this in the Java library so I don't have to manually loop over the array? Maybe I have been spoiled by C++'s excellent support for algorithmically focused code, where I can just write:
Java 库中是否有这样的方法，因此我不必手动遍历数组？也许我被 C++ 对算法重点代码的出色支持所宠坏，我可以在其中编写：
#include <algorithm>
bool found_null = (std::find(array + from, array + to, 0) != array + to);
回答by SLaks
Check whether Arrays.asList(myArray).contains(null).
检查是否Arrays.asList(myArray).contains(null).
To check part of an array, check whether
要检查数组的一部分，请检查是否
Arrays.asList(myArray).subList(from, to).contains(null)
This will not create unnecessary copies of the array; both asListand subListcreate ArrayListand RandomAccessSubListobjects that wrap the original array without copying it.
这不会创建不必要的数组副本；双方asList并subList创建ArrayList和RandomAccessSubList对象那套原始数组不复制它。
回答by Bozho
Apache commons-langgives you ArrayUtils.contains(array, null)
Apache commons-lang给你ArrayUtils.contains(array, null)
For the range: ArrayUtils.contains(Arrays.copyOfRange(array, from, to), null)
对于范围： ArrayUtils.contains(Arrays.copyOfRange(array, from, to), null)
