Invoke Setters And Getters Of A POJO Class Using Variable Name At Runtime.

We can invoke setters and getters of a POJO class by using its variable name by using Reflection API of java.

Reflection API is used to examine the behavior of classes, interfaces, methods at runtime.

When we make some generics methods, we will need some common behavior which will work with any kind of class. For example, a common insertion method, to insert any kind of class(entity) data in the database. This will reduce code redundancy and improve the performance of the program. 

Reflection API of java make it possible for us.

We use Method class and its methods to achieve this goal.

Here is an example(Invoking getter method at runtime and get the desired output):-

HelloWorld.java

import java.lang.reflect.*;
public class HelloWorld{
    String name;
    public HelloWorld(String name){
    this.name=name;
    }
    public void setName(String name){
    this.name=name;
    }
    public String getName(){
     return name;
    }
    // this method does the work to invoke the method at runtime
 protected String getValueFromObject(Object object, String fieldName) {
        // get class
        Class clazz = object.getClass() ;
        if (clazz == null) {
          return null;
        }
     Object valueObject =null;
        // get object value using reflection
        String getterName = "get" + fieldName;
        try {
          Method method = clazz.getDeclaredMethod(getterName);
          valueObject = method.invoke(object,(Object[]) null);
        } catch (Exception e) {
          System.out.println(e);
        }
        return valueObject != null ? valueObject.toString() : "";
      }
     public static void main(String []args){
     HelloWorld h = new HelloWorld("Hello World");
     h.getName();
     System.out.println(h.getValueFromObject(h,"Name"));
     }
}

To Run it:-

$ javac HelloWorld.java

$ java HelloWorld

Output:-

Hello World