Method class isSynthetic() method in Java

java.lang.reflectMethod class help us to get information of a single method on a class or interface. This class also provides access to the methods of classes and invoke them at runtime.

isSynthetic() method of Method class: This function checks whether Method Object is a synthetic construct or not. If the method is a synthetic construct then the function returns true otherwise it will return false.

Synthetic Construct: Synthetic Construct are Class, Fields, and Methods that are created by the Java compiler for internal purposes.

Syntax:

public boolean isSynthetic()

Return Value: This method returns true if and only if Method is a synthetic construct as specified by the JVM. Else it returns false.

Below programs illustrates isSynthetic() method of Method class:

Example 1:

In below program when the main method creates an object of nested private class Demo and tries to access the private variable name “message”. When it is compiled, it will create a synthetic method. The details of that synthetic method can be obtained by getting the object of that method with the use of isSynthetic() method as shown in below program.

// Java program to demonstrate isSynthetic()
// method of Method Class.

import java.lang.reflect.Method;

public class GFG {

    // create Demo class
    private static final class Demo {
        private String message = "A Computer Science"
                                 + " portal for geeks";
    }

    // create main method
    public static void main(String args[])
    {

        try {
            // create object of Demo class
            Demo obj = new Demo();

            // print message of nested demo class
            System.out.println("private Message"
                               + " variable of Demo class"
                               + obj.message);

            // get class object of demo class
            Class classobj = obj.getClass();

            // get list of declared method objects
            // of class object of Demo
            Method[] methods = classobj.getDeclaredMethods();

            // loop through method list
            for (Method method : methods) {

                // check method is Synthetic or not
                boolean isSynthetic = method.isSynthetic();

                // print result
                System.out.println(method
                                   + " method is Synthetic Method :"
                                   + isSynthetic);
            }
        }
        catch (Exception e) {

            // Print Exception if any Exception occurs
            e.printStackTrace();
        }
    }
}

Output:

private Message variable of Demo classA Computer Science portal for geeks
static java.lang.String GFG$Demo.access$100(GFG$Demo) method is Synthetic Method :true

Example 2: Program to return all the Synthetic construct Methods of BigInteger class.

Explanation: In this Method, at first, BigInteger Class Object is created. After creating Class Object of BigInteger Class, a list of Method Objects is created by calling getMethods() of class Object. Iterate through Method list and get Synthetic Method by checking Method is Synthetic or not using isSynthetic(). At last print Synthetic Method name.

// Java program to Demonstrate isSynthetic()
// method of Method Class.

import java.lang.reflect.Method;
import java.math.BigInteger;

public class GFG {

    // create main method
    public static void main(String args[])
    {

        try {

            // create class object for class BigInteger
            Class c = BigInteger.class;

            // get list of Method object
            Method[] methods = c.getMethods();

            System.out.println("Synthetic Methods"
                               + " of BigInteger Class are");
            // Loop through Methods list
            for (Method m : methods) {

                // check whether the method is
                // Synthetic Method or not
                if (m.isSynthetic()) {
                    // Print Method name
                    System.out.println("Method: "
                                       + m.getName());
                }
            }
        }
        catch (Exception e) {
            // print Exception if any Exception occurs
            e.printStackTrace();
        }
    }
}

Output:

Synthetic Methods of BigInteger Class are
Method: compareTo

Reference:

• https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Method.html#isSynthetic–
• https://nagakishoresidde.wordpress.com/2015/10/18/synthetic-constructs-in-java/