How do we create an instance of VarHandle in Java 9?

Generally speaking, Variable handle is just a typed reference to a variable. It will be an array element of the class, an instance or a static field . The VarHandle class can provide write and read access to variables under specific conditions. They are immutable and have no visible conditions. Additionally, they cannot be subdivided, each VarHandle has a generic type T, which is the type of each variable represented by this VarHandle. The goal of VarHandle is to define a standard for calling the equivalent sum of java.util.concurrent.atomic and sun.misc.Unsafe operations on a field. Array elements.

In the following example, we can use the MethodHandle.lookup() method to create a VarHandle instance.

Example

import java.lang.invoke.VarHandle;
import java.lang.invoke.MethodHandles;

public class VarHandleInstanceTest {
   public static void main(String args[]) {
      try {
         <strong>VarHandle </strong>fieldHandle = <strong>MethodHandles.lookup().in</strong>(Student.class).<strong>findVarHandle</strong>(Student.class, "<strong>studentId</strong>", int.class);
         System.out.println("VarHandle instance created successfully!!!");
      } catch (NoSuchFieldException | IllegalAccessException e) {
         e.printStackTrace();
      }
   }
}

<strong>// Stundent class</strong>
class Student {
   protected int studentId;
   private String[] marks;
   public Student() {
      studentId = 0 ;
      marks = new String[] {"75" , "85" , "95"} ;
   }
}

Output

<strong>VarHandle instance created successfully!!!</strong>

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