Java non access modifiers
9 likes4,430 views
The document discusses the non-access modifiers in Java including final, static, abstract, strictfp, native, synchronized, transient, and volatile. It provides details on what types of classes, methods, or variables each modifier can be applied to and how each modifier affects the behavior or implementation of code.
![public static void main(String[] args){ }
www.JAVA9S.com](https://image.slidesharecdn.com/javanonaccessmodifiers-120701091327-phpapp01/85/Java-non-access-modifiers-11-320.jpg)
Java non access modifiers
- 1. Java Non Access Modifiers SCJP/OCJP exam objectives – 1.1,1.3,1.4 By, Srinivas Reddy.S www.JAVA9S.com
- 2. Non Access Modifiers • final • static • abstract • strictfp • native • synchronized • transient • volatile www.JAVA9S.com
- 3. final • final can be applied for classes, methods, instance variables, local variables. • A class marked as final cannot be extended. • A method marked with final cannot be overridden. • A primitive data type or an object reference will not change its value or object when marked final. www.JAVA9S.com
- 4. static public class Ford{ int maxSpeed; public Ford(int maxSpeed){ Ford f = new Ford(100); this.maxSpeed = maxSpeed; } Ford a = new Ford(200); public void move(){ Ford e = new Ford(150); int speed = 0; while(speed<maxSpeed){ System.out.println(“Racing with speed”+speed); speed++; } function f.move(); } of method a.move(); public void printCarInfo(){ e.move(); varies from Object System.out.println(“Car name : Ford“); to object System.out.println(“ Car weight : 230”); f.printCarInfo(); System.out.println(“Engine Capacity: 3000cc”); a.printCarInfo(); Same output } e.printCarInfo(); } www.JAVA9S.com
- 5. static Virtual Memory .Class File Members marked as static belong to the Class file and not the instances www.JAVA9S.com
- 6. static • static can be applied for methods and variables. • A method or variable marked as static belongs to class file. • A static member should be accessed using the class name. www.JAVA9S.com
- 7. Accessing static members • static members can be accessed using the class name. E.g., public class Ford{ public static void printCarInfo(){ System.out.println(“Car name : Ford“); System.out.println(“ Car weight : 230”); System.out.println(“Engine Capacity: 3000cc”); } } Ford.printCarInfo(); www.JAVA9S.com
- 8. Accessing static members public class Ford{ public static void printCarInfo(){ System.out.println(“Car name : Ford“); System.out.println(“ Car weight : 230”); System.out.println(“Engine Capacity: 3000cc”); } } public class FordShowRoom(){ public class FordShowRoom(){ public void getCarInfo(){ public void getCarInfo(){ Ford f = new Ford(); Ford.printCarInfo(); f.printCarInfo(); } } } } www.JAVA9S.com
- 9. static - rules • The static variable and static methods are called class members. • A method marked as static can only access other static methods and variables directly. • To access the instance variables and methods, a static method should have an instance on which the object members should be invoked. • Any instance can access the static variables and can change them. But, the changes will reflect for all the objects. • Members marked as static can be final www.JAVA9S.com
- 11. public static void main(String[] args){ } www.JAVA9S.com
- 12. abstract public class Car{ public void move(){ System.out.println(“Moves at max 40 kmph”); } } Benz Ford BMW Ferrari Toyota www.JAVA9S.com
- 13. abstract public abstract class Car{ public abstract void move(); } public class Ford extends Car{ public void move(){ System.out.println(“Move at 120 kmph”); } } public class Benz extends Car{ public void move(){ System.out.println(“Move at 200 kmph – Comfortably ”); } } www.JAVA9S.com
- 14. abstract - rules • abstract can be applied for classes and methods only. • When a method is marked as abstract – It should not have implementation. E.g., public abstract void move(); • Abstract methods should end with ‘;’ and not with ‘{ }’. www.JAVA9S.com
- 15. abstract - Rules • When a method marked as abstract, the whole class should be marked as abstract. • A class can be abstract with out any abstract methods in it. • We cannot create an instance of abstract class. • An abstract method should be overridden in the subclass or should be marked as abstract. www.JAVA9S.com
- 16. abstract - rules • Abstract classes can have concrete(non- abstract) methods in it. • Abstract methods cannot be marked as final. • Abstract classes cannot be marked as final. • Abstract methods cannot be static. • Abstract methods cannot be private www.JAVA9S.com
- 17. abstract - rules • Cannot create an instance of abstract class??? – An abstract class can contain abstract methods which does not have functionality and if we can create objects, we do not have functionality in abstract methods. – So, abstract classes are incomplete and are not eligible for creating instances. www.JAVA9S.com
- 18. strictfp • strictfp can only be declared for methods and classes. • When declared, the code inside a class or method will conform to IEEE754 standard which makes the methods or classes behave in a platform independent way regarding the floating points. • strictfp cannot be used with abstract. www.JAVA9S.com
- 19. native • native modifier can only be applied to methods. • A native method will always have platform dependent code like C. • A native method should not have the implementation and should end with ‘;’. • A native methods implementation is omitted. www.JAVA9S.com
- 20. synchronized • synchronized can only be applied for methods. • Any method or block that is synchronized will only allow one single thread to execute the code at a given time. • synchronized can be used with any access modifier. www.JAVA9S.com
- 21. transient • only instance variables can be marked as transient. • A variable marked as transient will not be serialized. volatile • volatile can only be applied to instance variables www.JAVA9S.com
- 22. Access and non access modifiers - classes • public • default • abstract • strictfp • final www.JAVA9S.com
- 23. Access and non access modifiers- variables and members Methods Instance variables Local variables public public - protected protected - default default - private private - static static - final final final strictfp - - native - - - transient - synchronized - - abstract - - www.JAVA9S.com
- 24. Thank you Follow me on to get more updates on latest video posts Subscribe on http://www.youtube.com/user/java9s Twitter : @java9s facebook: www.facebook.com/java9s www.JAVA9S.com