Why is multiple inheritance not possible in Java?

Java Interview Questions and Answers (part 1)

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140. Why is multiple inheritance not possible in Java?

It depends on how you understand "inheritance". Java can only "extends" one super class, but can "implements" many interfaces; that doesn't mean the multiple inheritance is not possible. You may use interfaces to make inheritance work for you. Or you may need to work around. For example, if you cannot get a feature from a class because your class has a super class already, you may get that class's feature by declaring it as a member field or getting an instance of that class. So the answer is that multiple inheritance in Java is possible.

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Other Interview Questions

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• What does a well-written OO program look like?
• Can you have virtual functions in Java?
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• How could Java classes direct program messages to the system console, but error messages, say to a file?
• What's the difference between an interface and an abstract class?
• Name the containers which uses Border Layout as their default layout?
• What do you understand by Synchronization?
• What is Collection API?
• Is Iterator a Class or Interface? What is its use?
• What is similarities/difference between an Abstract class and Interface?
• How to define an Abstract class?
• How to define an Interface?
• If a class is located in a package, what do you need to change in the OS environment to be able to use it?
• How many methods in the Serializable interface?
• How many methods in the Externalizable interface?
• What is the difference between Serializalble and Externalizable interface?
• What is a transient variable?
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• How are Observer and Observable used?
• What is synchronization and why is it important?
• What are synchronized methods and synchronized statements?
• What are three ways in which a thread can enter the waiting state?
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• What is thread?
• What is multi-threading?
• How does multi-threading take place on a computer with a single CPU?
• How to create a thread in a program?
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• What happens when a thread cannot acquire a lock on an object?
• What is the difference between Process and Thread?
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• If a method is declared as protected, where may the method be accessed?
• What is an Iterator interface?
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• What is a native method?
• How can you write a loop indefinitely?
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• When should the method invokeLater()be used?
• How many methods in Object class?
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• What is the numeric promotion?
• Is the numeric promotion available in other plantform?
• What is the difference between the Boolean & operator and the && operator?
• When is the ArithmeticException throwQuestion: What is the GregorianCalendar class?
• What is the SimpleTimeZone class?
• How can a subclass call a method or a constructor defined in a superclass?
• What is the Properties class?
• What is the purpose of the Runtime class?
• What is the purpose of the System class?
• What is the purpose of the finally clause of a try-catch-finally statement?
• What is the Locale class?
• What is an abstract method?
• What is the difference between interface and abstract class?
• What is a static method?
• What is a protected method?
• What is the difference between a static and a non-static inner class?
• What is an object's lock and which object's have locks?
• When can an object reference be cast to an interface reference?
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• Which package has light weight components?
• What are peerless components?
• What is the difference between the Font and FontMetrics classes?
• What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?
• What classes of exceptions may be caught by a catch clause?
• What is the difference between throw and throws keywords?
• If a class is declared without any access modifiers, where may the class be accessed?
• What is the Map interface?
• Does a class inherit the constructors of its superclass?
• Name primitive Java types.
• Which class should you use to obtain design information about an object?
• How can a GUI component handle its own events?
• How are the elements of a GridBagLayout organized?
• What advantage do Java's layout managers provide over traditional windowing systems?
• What are the problems faced by Java programmers who don't use layout managers?
• What is the difference between static and non-static variables?
• What is the difference between the paint() and repaint() methods?
• What is the purpose of the File class?
• Why would you use a synchronized block vs. synchronized method?
• What restrictions are placed on method overriding?
• What is casting?
• Explain the usage of the keyword transient?
• What class allows you to read objects directly from a stream?
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• What is the Set interface?
• How can you force garbage collection?
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• What are the Object and Class classes used for?
• What is Serialization and deserialization?
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• What is design by contract?
• What are use cases?
• What is scalability and performance?
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