[Learn Java for beginners] reflection learning notes and java learning notes

[Learn Java for beginners] reflection learning notes and java learning notes

Example

@ SuppressWarnings ("unused") public class Person {public String Name; private int Age; public Gender; private static String Species = "human"; public Person () {Name = "Alias name"; Age =-1;} public Person (String Name) {name = name;} private Person (String Name, int age) {name = Name; age = age;} private Person (Gender g) {Gender = g;} public void Run () {System. out. println (Name + "Run! ");} Public void Attack () {System. out. println (Name +! ");} Public void Attack (String name) {System. out. println (Name +" "+ name + "! ");} Private void Eat (String food) {System. out. println (Name + "eat" + food);} public void Introduce () {System. out. println ("My Name is" + Name + ", I am" + Age + "years old. ");} Public static void PlayGame (String gameName) {System. out. println ("play" + gameName + "game");} public static void main (String [] args) {System. out. println ("main"); for (String s: args) System. out. println (s) ;}} enum Gender {Male, Female}

No-argument constructor of the reflection class:

@ Test // The non-argument constructor of the reflection Class public void constructor1 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Constructor c = clazz. getConstructor (); Person p = (Person) c. newInstance (); Person p1 = (Person) clazz. newInstance (); p. introduce (); p. run (); p1.Introduce (); p1.Run ();}

The constructor of the reflection class has the following parameters:

@ Test // The constructor2 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Constructor c = clazz. getConstructor (String. class); Person p = (Person) c. newInstance ("James"); p. introduce (); p. run ();}

Private constructor of the reflection class:

@ Test // private constructor of the reflection Class public void constructor3 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); // when reflecting private constructors, you must use the getDeclaredConstructor method Constructor c = clazz. getDeclaredConstructor (String. class, int. class); c. setAccessible (true); // violent reflection Person p = (Person) c. newInstance ("James", 25); p. introduce (); p. run ();}

Public parameter-free method of the reflection class:

@ Test // public Non-argument public void method1 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Person p = (Person) clazz. newInstance (); Method method = clazz. getMethod ("Run"); method. invoke (p );}

Public Parameter Method of the reflection class:

@ Test // public parameter public void method2 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Person p = (Person) clazz. newInstance (); Method method = clazz. getMethod ("Attack", String. class); method. invoke (p, "Li Si ");}

The reflection class has the following private parameter methods:

@ Test // The Private parameter public void method3 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Person p = (Person) clazz. newInstance (); Method method = clazz. getDeclaredMethod ("Eat", String. class); method. setAccessible (true); method. invoke (p, "banana ");}

Static Parameter Method of the reflection class:

@ Test // static parametric public void method4 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Person p = (Person) clazz. newInstance (); Method method = clazz. getDeclaredMethod ("PlayGame", String. class); method. setAccessible (true); method. invoke (p, "mine clearance ");}

The main method of the reflection class:

@ Test // main method of the reflection Class public void method5 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Person p = (Person) clazz. newInstance (); Method method = clazz. getDeclaredMethod ("main", String []. class); method. setAccessible (true); method. invoke (p, (Object) new String [] {"1", "2 "});}

Public reflection fields:

@ Test // public reflection Class field public void field1 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Person p = (Person) clazz. newInstance (); Field field = clazz. getField ("Name"); System. out. println (field. get (p); field. set (p, "Wang Wu"); p. introduce ();}

Private reflection fields:

@ Test // public void field2 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Person p = (Person) clazz. newInstance (); Field field = clazz. getDeclaredField ("Age"); field. setAccessible (true); System. out. println (field. get (p); field. set (p, 7); p. introduce ();}

Private and static reflection fields:

@ Test // reflection Class private static field public void field3 () throws Exception {Class clazz = Class. forName ("pro. shaowei. reflect. person "); Person p = (Person) clazz. newInstance (); Field field = clazz. getDeclaredField ("Species"); field. setAccessible (true); System. out. println (field. get (p); field. set (p, "non-dead"); System. out. println (field. get (p ));}