Java源代码中的“ .class”到底是什么

Question

I was surfing in SO & I found syntax in Java as below:

String.class.getDeclaredField("value");

I could not understand how it works

Example:

In System.out.println(); out is static variable in System class of PrintWriter

Can any one explain what String.class.getDeclaredField("value"); and it's returning object of Field class means?

I just looked & I couldn't find class property(field) in String class.

What is it actually doing?

Thanks in advance.

Answer 1

String.class is a literal that represents the String class which is of type Class<String> . getDeclaredField() is a method defined on the class Class .

see also: What is a class literal in Java?

The literals are defined in the Java Language Specification 15.8.2

Answer 2

查找Java Reflection API和Class.getDeclaredField() 。