Reflection in java

• Reflection is used to analyse a class at runtime.
• It is used to get the structure of a class at run time.
• Through reflection we are able to retrieve the information like constructors, fields and methods associated with the class.
• Reflection is used to change the values of data fields in objects.
  
  For example consider the class 'Person'
  
  package com.java;
  
  public class Person {
  private String name;
  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;
  }
  private int age;
  
  }
  
  Reflection class
  
  package com.java;
  import java.lang.reflect.Constructor;
  import java.lang.reflect.Field;
  import java.lang.reflect.Method;
  public class ReflectionExample {
  
  public static void main(String[] args) {
  try {
  // Creates an object of type Class which contains the information of
  // the class String
  Class cl = Class.forName("com.java.Person");
  
  // getDeclaredFields() returns all the constructors of the class.
  Constructor cnst[] = cl.getConstructors();
  
  // getFields() returns all the declared fields of the class.
  Field fld[] = cl.getDeclaredFields();
  
  // getMethods() returns all the declared methods of the class.
  Method mtd[] = cl.getMethods();
  System.out.println("Name of the Constructors of the String class");
  
  for (int i = 0; i < cnst.length; i++) {
  System.out.println(cnst[i].getName().toString());
  }
  
  System.out.println("Name of the Declared fields");
  
  for (int i = 0; i < fld.length; i++) {
  System.out.println(fld[i].getName().toString());
  }
  
  System.out.println("Name of the Methods");
  
  for (int i = 0; i < mtd.length; i++) {
  System.out.println(mtd[i].getName().toString());
  }
  
  } catch (ClassNotFoundException e) {
  e.printStackTrace();
  }
  }
  
  }
  
  Result
  Name of the Constructors of the String class
  com.java.Person
  Name of the Declared fields
  name
  age
  Name of the Methods
  getAge
  setAge
  getName
  setName
  wait
  wait
  wait
  hashCode
  getClass
  equals
  toString
  notify
  notifyAll