package cn.com.reflect;
public class Person {
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Person(int age) {
super();
this.age = age;
}
public Person(String name) {
super();
this.name = name;
}
public Person() {
super();
}
public Person(String name, int age) {
super();
this.name = name;
this.age = age;
}
}
package cn.com.reflect;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
public class ReflectDemo4 {
public static void main(String[] args) {
Class<?> clazz = null;
try {
clazz = Class.forName("cn.com.reflect.Person");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
Person demo1 = null;
Constructor<?>[] con = clazz.getConstructors();
try {
demo1 = (Person) con[0].newInstance(12);
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
System.out.println(demo1.getAge());
}
}
java.lang.IllegalArgumentException: wrong number of arguments
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at cn.com.reflect.ReflectDemo4.main(ReflectDemo4.java:20)
Exception in thread "main" java.lang.NullPointerException
at cn.com.reflect.ReflectDemo4.main(ReflectDemo4.java:31)