检查 java.lang.reflect.Field 类型是否为字节数组
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Check if java.lang.reflect.Field type is a byte array
提问by Paulius Matulionis
I don't do much of reflection so this question might be obvious. For e.g. I have a class:
我没有做太多反思，所以这个问题可能很明显。例如，我有一堂课：
public class Document {
private String someStr;
private byte[] contents;
//Getters and setters
}
I am trying to check if the field contentsis an instance of byte array. What I tried:
我正在尝试检查该字段contents是否是字节数组的实例。我试过的：
Class clazz = Document.class;
Field[] fields = clazz.getDeclaredFields();
for (Field field : fields) {
if (field.getType().isArray()) {
Object array = field.getType();
System.out.println(array);
}
}
The output of this code is: class [B. I see that byte array is found, but if I do:
这段代码的输出是：class [B。我看到找到了字节数组，但如果我这样做：
if (array instanceof byte[]) {...}
This condition is never true. Why is that? And how to check if the object contains fields which are of type of byte[]?
这种情况是从来没有的true。这是为什么？以及如何检查对象是否包含类型为 的字段byte[]？
回答by axtavt
array instanceof byte[]checks whether arrayis an object of type byte[]. But in your case arrayis not a byte[], it's an object of type Classthat represents byte[].
array instanceof byte[]检查是否array是类型的对象byte[]。但在你的情况下array不是 a byte[]，它是一个Class代表byte[].
You can access a Classthat represents some type Tas T.class, therefore you need the following check:
您可以访问Class表示某种类型T的T.class，因此，你需要以下检查：
if (array == byte[].class) { ... }
回答by Peter Lawrey
if the array is a class only instanceof Classwill be true..
如果数组是一个类只会instanceof Class是真的..
If you want to check the type of a field you can use
如果要检查字段的类型，可以使用
if(field.getType() == byte[].class)
回答by Jesper
Try this:
试试这个：
Class<?> cls = field.getType();
if (cls.isAssignableFrom(byte[].class)) {
System.out.println("It's a byte array");
}
回答by Brian Agnew
See this useful tutorial from Oracle
Array types may be identified by invoking Class.isArray()
数组类型可以通过调用 Class.isArray() 来识别
回答by assylias
If you try:
如果你试试：
Class<?> array = field.getType();
System.out.println(array.getCanonicalName());
it prints byte[]. But @axtavt's answer is better.
它打印byte[]。但@axtavt 的回答更好。
