What are the three methods of java reflection

There are three methods of java reflection: 1. Get the Class object; 2. Get the constructor, fields and methods of the class; 3. Call methods and access fields through reflection. Detailed introduction: 1. Obtain the Class object: You can obtain the Class object through one of three methods: object acquisition, class name acquisition, and fully qualified name acquisition of the class, so as to obtain information about the class; 2. Obtain the constructor method of the class , Fields and methods: Through the Class object, you can obtain the constructor, fields and methods of the class; 3. Call methods and access fields through reflection, etc.

Operating system for this tutorial: Windows 10 system, Dell G3 computer.

In Java, reflection is a powerful mechanism that allows obtaining class information, calling class methods, accessing class fields, etc. at runtime. Reflection provides three main methods to implement these operations:

1. Obtain the Class object: You can use one of the following three methods to obtain the Class object to obtain information about the class. information.

Get through the object: Use the getClass() method of the object.

MyClass obj = new MyClass();
Class<?> myClass = obj.getClass();

Get by class name: Use the class attribute of the class name.

Class<?> myClass = MyClass.class;

Get through the fully qualified name of the class: use the Class.forName() method.

Class<?> myClass = Class.forName("com.example.MyClass");

2. Obtain the constructor, fields and methods of the class: Through the Class object, you can obtain the constructor, fields and methods of the class.

Get the constructor:

Constructor<?>[] constructors = myClass.getConstructors();

Get the field:

Field[] fields = myClass.getDeclaredFields();

Get the method:

Method[] methods = myClass.getMethods();

3, Call methods and access fields through reflection: Using Method objects and Field objects, you can call class methods and access field values.

Calling method:

Method myMethod = myClass.getMethod("methodName", parameterTypes);
myMethod.invoke(objectInstance, args);

Accessing fields:

Field myField = myClass.getDeclaredField("fieldName");
myField.setAccessible(true); // 如果字段是私有的，需要设置为可访问
Object fieldValue = myField.get(objectInstance);

These three methods provide the flexibility to obtain class information, call methods and access fields at runtime. However, be aware that reflection operations may incur performance overhead and require exception handling when used.

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