Method overriding inward Java
Method overriding inward Java is a concept based on polymorphism OOPS concept which allows programmer to do ii methods amongst same get upwards together with method signature on interface together with its diverse implementation together with actual method is called at runtime depending upon type of object at runtime. Method overriding allows you lot to write flexible together with extensible code inward Java because you lot tin innovate novel functionality amongst minimal code change. Method overriding is dissimilar than method overloading inward Java which nosotros accept discussed inward in conclusion article. In method overloading, Only get upwards of ii overloaded methods are same precisely method signature must last dissimilar spell inward method overriding, method signature must last same. method overriding stand upwards for truthful polymorphic behaviour, where exclusively get upwards needs to last same underlying method logic tin last different. In this Java tutorial nosotros volition see What is method overriding inward Java, Rules to override method inward Java together with an representative of How to override method inward Java. We won't utter over difference betwixt method overloading together with overriding inward Java, may last about other post.
Rules of method overriding inward Java
There are few rules which needs to last followed spell overriding whatsoever method inward Java, failure to follow these rules termination inward compile fourth dimension mistake inward Java. 1) First together with almost of import dominion regarding method overriding inward Java is that you lot tin exclusively override method inward sub class. You tin non override method inward same class.
2) Second of import dominion of method overriding inward Java that get upwards together with signature of method must last same inward Super class together with Sub class or inward interface together with its implementation.
3) Third dominion to override method inward Java is that overriding method tin non trim back accessibility of overridden method inward Java. For representative if overridden method is populace than overriding method tin non last protected, soul or package-private; But contrary is truthful overriding method tin growth accessibility of method inward Java, i.e. if overridden method is protected than overriding method tin last protected or public.
4) Another worth noting dominion of method overriding inward Java is that overriding method tin non throw checked Exception which is higher inward hierarchy than overridden method. Which agency if overridden method throws IOException than overriding method tin non throw java.lang.Exception inward its throws clause because java.lang.Exception comes higher than IOException inward Exception hierarchy. This dominion doesn't apply to RuntimeException inward Java, which is non fifty-fifty demand to last declared inward throws clause inward Java.
5) You tin non override private, static together with final method inward Java. soul together with static method are bonded during compile fourth dimension using static binding inward Java and doesn't resolve during runtime. overriding in conclusion method inward Java is compile fourth dimension error. Though soul together with static method tin last hidden if you lot declare about other method amongst same together with signature inward sub class.
6) Overridden method is called using dynamic binding inward Java at runtime based upon type of Object. As shown inward next representative of method overloading.
7) If you lot are extending abstract class or implementing interface than you lot demand to override all abstract method unless your class is non abstract. abstract method tin exclusively last used yesteryear using method overriding.
8) Always usage @Override annotation spell overriding method inward Java. Though this is non dominion precisely its 1 of the best Java coding do to follow. From Java vi you lot tin usage @Override annotation on method inherited from interface every bit well.
Method Overloading Example inward Java
Now nosotros know what is method overriding inward Java together with rules of method overriding, It's fourth dimension to meet an representative of how to override method inward Java. In this representative nosotros accept used Runnable interface which has an abstract run() method. We accept ii class Task together with PeriodicTask which implements Runnable interface together with override run method. For the purpose of demonstrating how method overriding industrial plant inward Java nosotros are calling run() method inward same thread, which you lot should not, meet difference betwixt run together with starting fourth dimension method to know why. Because run() is overridden inward ii split class, telephone phone to run() method volition last resolved during runtime depending upon type of Object.
/**
*
* Java plan to demonstrate how to override method inward Java.
* Overridden method are resolved during runtime based upon type of object
*
* @author Javin
*/
public class CollectionTest {
public static void main(String args[]) {
Runnable chore = new Task();
task.run(); //call overridden method inward Task
chore = new PeriodicTask();
task.run(); //calls overridden method inward PeriodicTas
}
}
class Task implements Runnable{
@Override
public void run() {
System.out.println("Run method overridden inward Task class");
}
}
class PeriodicTask extends Task{
@Override
public void run() {
System.err.println("overridden method run() inward PeriodicTask class");
}
}
Output:
Run method overridden inward Task class
overridden method run() inward PeriodicTask class
*
* Java plan to demonstrate how to override method inward Java.
* Overridden method are resolved during runtime based upon type of object
*
* @author Javin
*/
public class CollectionTest {
public static void main(String args[]) {
Runnable chore = new Task();
task.run(); //call overridden method inward Task
chore = new PeriodicTask();
task.run(); //calls overridden method inward PeriodicTas
}
}
class Task implements Runnable{
@Override
public void run() {
System.out.println("Run method overridden inward Task class");
}
}
class PeriodicTask extends Task{
@Override
public void run() {
System.err.println("overridden method run() inward PeriodicTask class");
}
}
Output:
Run method overridden inward Task class
overridden method run() inward PeriodicTask class
That's all on What is method overriding inward Java, Rules of method overriding inward Java together with an representative of How to override method inward Java. In summary think to override all abstract method spell extending cast abstract class or implementing interface. Overridden method are besides slower every bit compared to static together with in conclusion methods because of dynamic binding precisely it provides you lot flexibility, many popular Object oriented pattern principles are based upon method overriding inward Java.
Further Learning
How to traverse iterate or loop ArrayList inward Java
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