The getBoolean() method of java.lang.reflect.Field class is used to get the value of a static or instance Boolean field contains in a class. When a class contains a static or instance Boolean field and we want to get the value of that field then we can use this method to return the value of Field.
Syntax:
public boolean getBoolean(Object obj)
throws IllegalArgumentException,
IllegalAccessException
Parameters: This method accepts a single parameter obj which is the object to extract the boolean value from.
Return value: This method returns the value of the required boolean field.
Exception: This method throws following Exception:
- IllegalAccessException: This exception is thrown if Field object is enforcing Java language access control and the underlying field is inaccessible.
- IllegalArgumentException: This exception is thrown if the specified object is not an instance of the class or interface declaring the underlying field or if the field value cannot be converted to the type boolean by a widening conversion.
- NullPointerException: This exception is thrown if the specified object is null and the field is an instance field.
- ExceptionInInitializerError: This exception is thrown if the initialization provoked by this method fails.
Below programs illustrate getBoolean() method:
Program 1:
// Java program to demonstrate the above method import java.lang.reflect.Field; public class GFG { public static void main(String[] args) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException { // Create the User class object User user = new User(); // Get the isEmployee field object Field field = User.class.getField("isEmployee"); // Apply getBoolean Method on User Object // to get the value of isEmployee field boolean value = field.getBoolean(user); // print result System.out.println("Value of Boolean Field" + " isEmployee is " + value); // Now Get the isActive field object field = User.class.getField("isActive"); // Apply getBoolean Method on User Object // to get the value of isActive field value = field.getBoolean(user); // print result System.out.println("Value of Boolean Field" + " isActive is " + value); }} // sample User classclass User { // static boolean values public static boolean isEmployee = true; public static boolean isActive = false; public static boolean isEmployee() { return isEmployee; } public static void setEmployee(boolean isEmployee) { User.isEmployee = isEmployee; } public static boolean isActive() { return isActive; } public static void setActive(boolean isActive) { User.isActive = isActive; }} |
Value of Boolean Field isEmployee is true
Value of Boolean Field isActive is false
Program 2:
// Java program to demonstrate the above method import java.lang.reflect.Field; public class GFG { public static void main(String[] args) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException { // Create the mathDigit class object mathDigit math = new mathDigit(); // Get the isEmployee field object Field field = mathDigit.class.getField("isZero"); // Apply getBoolean Method on field Object // to get the value of isZero field boolean value = field.getBoolean(math); // print result System.out.println("Value: " + value); } // mathDigit class static class mathDigit { public static boolean isZero = false; public int number; public static boolean isZero() { return isZero; } public static void setZero(boolean isZero) { mathDigit.isZero = isZero; } public int getNumber() { return number; } public void setNumber(int number) { this.number = number; } }} |
Value: false
References: https://docs.oracle.com/javase/10/docs/api/java/lang/reflect/Field.html#getBoolean(java.lang.Object)
