Brief introduction and example __java of JAVA reflection mechanism-reflect

In the Java environment, the reflection mechanism allows a program to obtain a variety of its own definition information, such as properties and methods, that can also implement the ability to dynamically create objects of a class, change the contents of a property, or perform a specific method. So that Java has dynamic language characteristics, enhance the flexibility and portability of the program.

the function of the reflection mechanism:

1. At runtime, determine the type of any object to which it belongs;
2. Constructs an object of any class at run time;
3. Judge the member variables and methods of any class at run time;
4. Call a method of any object at run time, or even invoke the private method.

Java Reflection mechanism API:

The API that implements the Java reflection mechanism has a few points under the Java.lang.reflect package:

1.Class class: Representing a class;
2.Field class: Representing the member variables of the class;
3.Method class: Method of representing class;
4.Constructor class: Represents the construction method of class;
5.Array class: Provides a static method for dynamically creating arrays and accessing elements of an array. All methods in the class are static.

Sample code One:

/* Print out all the properties and methods of the String class */public
void Test () {
    Class C = String.class;
    Method[] methods = C.getmethods ();
    for (int i=0;i<methods.length;i++) {
        System.out.println (methods[i].getname);
    }
    fields[] Fields = C.getfields ()
    for (Field f:fields) {
        System.out.println (F.gettype () + "," +f.getname ());
    }
}

Example two:

/* Dynamically create object based on class name/public
void Test () {
    Class C = Class.forName ("Student");
    Student Student = (Student) c.newinstance ();
    Student.setname ("Tom");
    Student.setage (ten);
    SYSTEM.OUT.PRINTLN (student);
    Override ToString ()  method
}

Example three:

/* Dynamically create array objects, assign values and values for arrays/public
void Test () {
    Class c = class.forname ("java.lang.String");
    Create a String type array,the length is ten
    Object arr = array.newinstance (c,10);
    At the index =5, assignment the parameter value
    array.set (arr,5, "It is a Test");
    Get the index=5 value
    String s = (string) array.get (arr,5);
    System.out.println (s);
}

Click to see reflection for detailed reference