deepHashCode与字节数组

出于某种原因， Arrays.deepHashCode()不能与byte[] 。
还有其他等价物吗？

Answer 1

首先，不需要“深度”。 这是一个原始的。 你不需要Deep。

只需使用Arrays.hashCode(byte[] yourArray)

编辑：为了澄清，Deep意味着深入研究数组中包含的对象。 鉴于您正在处理基元，您只需在计算中使用原始值本身。 这就是为什么Deep方法都不围绕基元的原因。

Answer 2

接受的答案是正确的：使用Arrays.hashCode为byte []提供具有相同值的相同结果。 如果您有嵌套（深层）结构，则必须使用Arrays.deepHashCode 。

 import java.util.Arrays; public class A { public static void main(String[] args) { byte[] a = {10, 32, -43, 80}; byte[] b = {13, -40}; byte[] c = {10, 32, -43, 80}; System.out.println("NOTE: A and C have identical values, B differs"); System.out.println("Using byte[].hashCode(): A and C have different hash codes"); System.out.println("a = " + a.hashCode()); System.out.println("b = " + b.hashCode()); System.out.println("c = " + c.hashCode()); System.out.println("Using Arrays.hashCode(): A and C have identical hash codes"); System.out.println("a = " + Arrays.hashCode(a)); System.out.println("b = " + Arrays.hashCode(b)); System.out.println("c = " + Arrays.hashCode(c)); System.out.println("Using Arrays.deepHashCode(): A and C have identical hash codes"); System.out.println("a = " + Arrays.deepHashCode(new Object[]{a})); System.out.println("b = " + Arrays.deepHashCode(new Object[]{b})); System.out.println("c = " + Arrays.deepHashCode(new Object[]{c})); } } 

这导致输出：

 NOTE: A and C have identical values, B differs Using byte[].hashCode(): A and C have different hash codes a = 141847843 b = 329849131 c = 1119051810 Using Arrays.hashCode(): A and C have identical hash codes a = 1250930 b = 1324 c = 1250930 Using Arrays.deepHashCode(): A and C have identical hash codes a = 1250961 b = 1355 c = 1250961 

这是一个需要Arrays.deepHashCode的例子

 import java.util.Arrays; public class B { public static void main(String[] args) { Object[] d = {"abc", "def", new String[]{"ghi"}}; Object[] e = {"abc", "def", new String[]{"ghi"}}; System.out.println("NOTE: D and E have identical nested values"); System.out.println("Using Object[].hashCode(): different"); System.out.println("d = " + d.hashCode()); System.out.println("f = " + e.hashCode()); System.out.println("Using Arrays.hashCode(): still different"); System.out.println("d = " + Arrays.hashCode(d)); System.out.println("e = " + Arrays.hashCode(e)); System.out.println("Using Arrays.deepHashCode(): identical"); System.out.println("d = " + Arrays.deepHashCode(d)); System.out.println("e = " + Arrays.deepHashCode(e)); } } 

输出：

 NOTE: D and E have identical nested values Using Object[].hashCode(): different d = 241990244 f = 1943487137 Using Arrays.hashCode(): still different d = 1057745997 e = 709187068 Using Arrays.deepHashCode(): identical d = 95807651 e = 95807651 

Answer 3

如果你想要包含相同字节的两个字节数组具有等效的哈希码，那么使用deepHashCode确实是正确的，你只需要对byte []数组进行一些额外的转换。

 import java.utils.Arrays; public class A { public static void main(String[] args) { byte[] a = {10,32,-43,80}; byte[] b = {13,-40}; byte[] c = {10,32,-43,80}; // A and C will have different hash codes System.out.println(a.hashCode()); System.out.println(b.hashCode()); System.out.println(c.hashCode()); // A and C will now have equivalent hash codes System.out.println(Arrays.deepHashCode(new Object[]{a})); System.out.println(Arrays.deepHashCode(new Object[]{b})); System.out.println(Arrays.deepHashCode(new Object[]{c})); } } 

这导致输出类似于……

 // Hash Codes a = 16130931 b = 26315233 c = 32716405 // Deep hash codes a = 1250961 b = 1355 c = 1250961