Java - Variable Together With Method Hiding Example

If Java, if y'all are non careful y'all tin perchance hide both methods together with variables of the superclass. Influenza A virus subtype H5N1 champaign or variable is said to shroud all fields amongst the same elevate inward superclasses. Similarly, a static method amongst the same elevate inward a subclass tin shroud the method of the superclass. This tin Pb to subtle bugs, peculiarly if y'all are expecting a dissimilar method to live on called. In this article, I'll present y'all examples of both variable together with method hiding inward Java thus that y'all tin empathise together with avoid them inward the future.

1. Method Hiding

Method hiding is closely related to method overriding together with sometimes programmer hides the method trying to override it. The concept of overriding allows y'all to write code which behaves differently depending upon an object at runtime.

As I said, a static method amongst the same elevate inward a subclass tin shroud the method from superclass because a static method cannot live on overridden inward Java.

Here is an instance of method hiding inward Java:

class Parent {     public static void sleep() {     System.out.println("Sleeps at eleven PM");   } }   class Child extends Parent {     public static void sleep() {     System.out.println("Sleeps at nine PM");   } }   public class Code {     public static void main(String[] args) {     Parent p = new Parent();     Parent c = new Child();     p.sleep();     c.sleep();     } }   Output: Sleeps at 11 PM Sleeps at 11 PM

In this example, nosotros assume that p.sleep() volition telephone band the sleep() method from Parent shape together with c.sleep() volition telephone band the sleep() method from small-scale fry class, simply similar it happens inward overriding but because sleep() is a static method, instead of overriding nosotros convey hidden the sleep() method.

Since static method are resolved at compile-time, both are p.sleep() together with c.sleep() are resolved to sleep() method of Parent shape because the type of p together with c variable is Parent. If y'all take the static keyword from both methods thus it volition acquit equally expected.

Btw, inward Java, y'all cannot override a static method equally an event method or vice-versa. So, if y'all take static keyword from either subclass or superclass method y'all volition cash inward one's chips a compile-time mistake equally "This event method cannot override the static method from Parent" or "This static method cannot shroud the event method from Parent".

In short, a static method amongst the same elevate together with signature inward a subclass tin shroud a static method of the superclass. You tin farther join The Complete Java Masterclass to larn to a greater extent than nigh the static method inward Java. It's 1 of the most up-to-date course of didactics together with covers Java 12.

2. Variable Hiding

Influenza A virus subtype H5N1 champaign or variable amongst the same elevate inward subclass together with superclass is known equally variable hiding or champaign hiding inward Java. When a variable is hidden, y'all tin purpose super.variableName to access the value from a superclass.

Here is an instance of variable hiding inward Java:

public class Parent {   int historic menstruum = 30; }   class Child extends Parent {   int historic menstruum = 4;     public void age() {     System.out.println("Parent's age: " + super.age);     System.out.println("Child's age: " + age);   } }

As y'all tin see, y'all tin access the superclass value using super.age.


That's all nigh method together with variable hiding inward Java. I don't encourage y'all to purpose the same elevate inward both superclass together with subclass unless y'all are overriding. This demeanour tin number inward confusing code together with motility subtle issues. Instead, endeavor to avoid elevate shape together with render a to a greater extent than meaningful name.

Further Learning
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