Multiple inheritance possible in Java

Multiple inheritance possible in Java

• 1.
  Multiple inheritance In Java
• 2.
  • What isinheritance? • Example of inheritance • What is meant by multiple inheritance? • Example of multiple inheritance? • What is diamond problem? • What is actual problem? • Does java multiple inheritance possible with interfaces? • Multiple inheritance possible and its example is…
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  What is inheritance? •An object which acquires the properties of another object is called inheritance • Properties means code & data/ method & fields
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  Simple example ofinheritance class First { int i=10; void inherit() { System.out.println("Hello"); } } class Second extends First { void inherit() { System.out.println("World"); } public static void main(String a[]) { Second s=new Second(); s.inherit(); System.out.println(s.i); } } C:Users>javac First.java C:Users>java Second World 10
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  What is meantby multiple inheritance? • An object which acquires properties from two are more objects at a time. Class C Class B Class A
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  Example of multipleinheritance? class First { int i=10; void inherit() { System.out.println("Hello"); } } class Second extends First { void inherit() { System.out.println("World"); } } class Third extends First,Second { void inherit() { System.out.println("Does this exists in java?"); } public static void main(String a[]) { Second s=new Second(); s.inherit(); System.out.println(s.i); } } C:Users>javac First.java First.java:16: error: '{' expected class Third extends First,Second ^ 1 error
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  What is DiamondProblem? Class A Class B Class C Class D
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  Example of multipleinheritance? class First { int i=10; void inherit() { System.out.println("Hello"); } } class Second extends First { void inherit() { System.out.println("World"); } } class Third extends First,Second { void inherit() { System.out.println("Does this exists in java?"); } public static void main(String a[]) { Second s=new Second(); s.inherit(); System.out.println(s.i); } } C:Users>javac First.java First.java:16: error: '{' expected class Third extends First,Second ^ 1 error
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  What is actualproblem? • James gosling in February 1995 gives an idea on why multiple inheritance is not supported in java • JAVA omits many rarely used, poorly understood, confusing features of C++ that in our experience bring more grief than benefit. This primarily consists of operator overloading (although it does have method overloading), multiple inheritance, and extensive automatic coercions
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  Multiple inheritance usinginterfaces interface inter { void dis(); } interface inter1 { void dis1(); } class myclass implements inter, inter1 { public void dis() { System.out.println("First interface method"); } public void dis1() { System.out.println("Second interface method"); } public static void main(String a[]) { myclass m=new myclass(); m.dis(); m.dis1(); } } Does this is the multiple inheritance or not? Yes, it is not an actual multiple inheritance but is just a syntactical multiple inheritance. Because the behaviors cannot be defined inside the methods of the interfaces.
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  Conclusion • As perthe above, multiple inheritance through classes in java is not possible and can be possible through interfaces but is not a full multiple inheritance. Pure Multiple Inheritance is possible in java HOW
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  • From theversion 8 of java, It supports default methods. • Default methods are the normal methods those can be implemented inside the interface • Ex: public interface Special { default void normalMethod() { System.out.println(“I am normal method"); } }
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  A class thatinherits the behaviors‘ from two parents called multiple inheritance. interface First { default void firstMethod(){ System.out.println(“I am the first default method in first interface"); } } interface Second { default void secondMethod(){ System.out.println(“I am the second default method in second interface"); } } public class Multiple implements First, Second { public static void main(String[] args) { Multiple Obj = new Multiple(); Obj.moveFast(); Obj.crawl(); } }
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  What if incaseof diamond problem? Interface First { default void same(){ System.out.println(“Same method of first interface"); } } interface Second { default void same(){ System.out.println(“Same method of second interface"); } } public class Third implements First, Second { public static void main(String[] args) { Third obj=new Third(); First.super.run(); //Call First’s same() method //or First.super.run(); //Call Second’s same() method } }