Examples of common Java reflection methods and java reflection examples

Examples of common Java reflection methods and java reflection examples

<Pre name = "code" class = "java"> import java. lang. reflect. constructor; import java. lang. reflect. field; import java. lang. reflect. method; class Point {int x; private int y; public Point () {x = 1; y = 2;} public void setX (int x) {this. x = x;} public void setY (int y) {this. y = y;} private Point (int x) {this (); this. x = x;} public Point (int x, int y) {super (); this. x = x; this. y = y;} public void printPoint () {System. out. println ("x =" + x + ", y =" + y) ;}} public class ReflectTest2 {public static void main (String [] args) throws Exception {// use the first method to create the object Class cls1 = Class. forName ("Point"); Constructor con1 = cls1.getConstructor (int. class, int. class); Point p1 = (Point) con1.newInstance (5, 6); p1.printPoint (); // use the second method to create an object Class cls2 = Point. class; Point p2 = (Point) cls2.newInstance (); // No parameter constructor p2.printPoint (); // use the third method to create the object Class cls3 = p1.getClass (); // use the setX Method of the p1 object to change the x value to 10 Method m1 = cls3.getMethod ("setX", int. class); m1.invoke (p1, 10); p1.printPoint ();/** Note: * getDeclaredConstructor can return the constructor of the specified parameter, * getConstructor can only return the public Constructor of the specified parameter. **/Constructor con2 = cls3.getDeclaredConstructor (int. class); // accessiblecon2.setAccessible (true) must be set for accessing private variables and functions; Point p4 = (Point) con2.newInstance (3); p4.printPoint (); // Field f1 = cls3.getField ("y"); // errorField f1 = cls3.getDeclaredField ("y"); f1.setAccessible (true); // obtain the y value of p1 System. out. println (f1.get (p1 ));}}

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