如何克隆 Java 字节数组？
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How do I clone a java byte array?
提问by JavaRocky
I have a byte array which i want to copy/clone to avoid calling code from modifying my internal representation.
我有一个字节数组，我想复制/克隆它以避免调用代码修改我的内部表示。
How do I clone a java byte array?
如何克隆 Java 字节数组？
采纳答案by polygenelubricants
JLS 6.4.5 The Members of an Array Type
The members of an array type are all of the following:
- The
public final field length, which contains the number of components of the array (length may be positive or zero).- The
publicmethodclone, which overrides the method of the same name in classObjectand throws no checked exceptions. The return type of the clone method of an array typeT[]isT[].- All the members inherited from class
Object; the only method ofObjectthat is not inherited is itsclonemethod.
JLS 6.4.5 数组类型的成员
数组类型的成员如下：
- 的
public final field length，其中包含所述阵列的组件的数量（长度可以是正的或零）。- 该
public方法clone，它覆盖类同名的方法Object，并没有抛出checked异常。数组类型的 clone 方法的返回类型T[]是T[].- 从 class 继承的所有成员
Object；唯一Object不被继承的clone方法是它的方法。
Thus:
因此：
byte[] original = ...;
byte[] copy = original.clone();
Note that for array of reference types, clone()is essentially a shallow copy.
请注意，对于引用类型的数组，clone()本质上是浅拷贝。
Also, Java doesn't have multidimensional arrays; it has array of arrays. Thus, a byte[][]is an Object[], and is also subject to shallow copy.
此外，Java 没有多维数组；它有数组数组。因此， abyte[][]是 an Object[]，并且也服从浅拷贝。
See also
也可以看看
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Other options
其他选项
Note that clone()returns a newarray object. If you simply want to copy the values from one array to an already existing array, you can use e.g. System.arraycopy.
请注意，clone()返回一个新的数组对象。如果您只是想将值从一个数组复制到一个已经存在的数组，您可以使用 eg System.arraycopy。
There's also java.util.Arrays.copyOfthat allows you to create a copy with a different length (either truncating or padding).
还java.util.Arrays.copyOf允许您创建具有不同长度（截断或填充）的副本。
Related questions
相关问题
回答by erickson
It's easy, and it's a great idea to do it.
这很容易，而且这样做是个好主意。
byte[] copy = arr.clone();
Note that the return type of the clone()method of arrays is the type of the array, so no cast is required.
注意clone()数组的方法的返回类型是数组的类型，所以不需要强制转换。
回答by TofuBeer
System.arraycopy(src, 0, dst, 0, src.length);
System.arraycopy(src, 0, dst, 0, src.length);
回答by Cooper
In order to avoid a possible Null Pointer Exception I use the following syntax:
为了避免可能的空指针异常，我使用以下语法：
byte[] copy = (arr == null) ? null : arr.clone();
