The isSynthetic() method of java.lang.reflect.Field is used to check whether Field Object is a synthetic field or not. If the field is a synthetic field then the function returns true otherwise it will return false. Synthetic Construct: Synthetic Construct is Class, Fields, and Methods that are created by the Java compiler for internal purposes. Syntax:
public boolean isSynthetic()
Parameters: This method accepts  nothing. Return: This method returns true if and only if this field is a synthetic field as defined by the Java Language Specification. Below programs illustrate isSynthetic() method: Program 1:Â
Java
// Java program to illustrate isSynthetic() methodÂ
import java.lang.reflect.Field;import java.time.Month;Â
public class GFG {Â
    public static void main(String[] args)        throws Exception    {Â
        // Get field object        Field field            = Numbers.class.getField("value");Â
        // check field is synthetic or not        System.out.println(            "The Field is isSynthetic: "            + field.isSynthetic());    }}Â
// sample Numbers classclass Numbers {Â
    // static short value    public static long value = 3114256;} |
Output:
The Field is isSynthetic: false
Program 2:Â
Java
// Java program to illustrate isSynthetic() methodÂ
import java.lang.reflect.Field;import java.time.DayOfWeek;Â
public class GFG {Â
    public static void main(String[] args)        throws Exception    {Â
        // Get field object of Month class        Field[] fields            = DayOfWeek.class                  .getDeclaredFields();Â
        for (int i = 0; i < fields.length; i++) {Â
            // print name of Fields            System.out.println(                "The Field "                + fields[i].toString()                + "\n is isSynthetic:"                + fields[i].isSynthetic());        }    }} |
Output:The Field public static final java.time.DayOfWeek java.time.DayOfWeek.MONDAY is isSynthetic:false The Field public static final java.time.DayOfWeek java.time.DayOfWeek.TUESDAY is isSynthetic:false The Field public static final java.time.DayOfWeek java.time.DayOfWeek.WEDNESDAY is isSynthetic:false The Field public static final java.time.DayOfWeek java.time.DayOfWeek.THURSDAY is isSynthetic:false The Field public static final java.time.DayOfWeek java.time.DayOfWeek.FRIDAY is isSynthetic:false The Field public static final java.time.DayOfWeek java.time.DayOfWeek.SATURDAY is isSynthetic:false The Field public static final java.time.DayOfWeek java.time.DayOfWeek.SUNDAY is isSynthetic:false The Field private static final java.time.DayOfWeek[] java.time.DayOfWeek.ENUMS is isSynthetic:false The Field private static final java.time.DayOfWeek[] java.time.DayOfWeek.$VALUES is isSynthetic:true
References: https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Field.html#isSynthetic–java
