反射获取Person类构造器并实例化对象演示

package _5_32;

 

 

import java.lang.reflect.Constructor;

 

class Person {

private String name;

private int age;

 

public Person() {

this.name = "default";

this.age = 0;

}

 

public Person(String name) {

this.name = name;

this.age = 0;

}

 

public Person(int age) {

this.name = "null";

this.age = age;

}

 

public Person(String name, int age) {

this.name = name;

this.age = age;

}

 

public String getName() {

return name;

}

 

public int getAge() {

return age;

}

 

public String toString() {

return "[" + this.name + " " + this.age + "]";

}

 

public int addAge(int a) {

return age + a;

}

}

 

public class GetConstructor {

public static void main(String[] args) {

Class<?> demo = null;

try {

demo = Class.forName("code0508.Person");

} catch (Exception e) {

e.printStackTrace();

}

 

// Get all constructors

Constructor<?>[] cons = demo.getConstructors();

try {

Constructor<?> cons0 = demo.getConstructor();

Constructor<?> cons1 = demo.getConstructor(String.class);

Constructor<?> cons2 = demo.getConstructor(int.class);

Constructor<?> cons3 = demo.getConstructor(String.class, int.class);

 

Person per1 = (Person) cons0.newInstance();

Person per2 = (Person) cons1.newInstance("ZhangShan");

Person per3 = (Person) cons2.newInstance(20);

Person per4 = (Person) cons3.newInstance("Lisi", 20);

 

System.out.println(per1); // [default 0]

System.out.println(per2); // [ZhangShan 0]

System.out.println(per3); // [null 20]

System.out.println(per4); // [Lisi 20]

 

} catch (Exception e) {

e.printStackTrace();

}

}

}