Given the following piece of code:public interface Guard{ void doYourJob();}abstract public class Dog implements Guard{ }which of the following statements is correct?

JAVA Interfaces and Abstract Classes
Given the following piece of code:public interface Guard{ void doYourJob();}abstract public class Dog implements Guard{ }which of the following statements is correct?

This code will not compile, because method doYourJob() in interface Guard must be defined abstract.

This code will not compile, because in the declaration of class Dog we must use the keyword extends instead of implements.

This code will compile without any errors.

This code will not compile, because class Dog must implement method doYourJob() from interface Guard.

This code will not compile, because method doYourJob() in interface Guard must be defined abstract.

This code will not compile, because in the declaration of class Dog we must use the keyword extends instead of implements.

This code will compile without any errors.

This code will not compile, because class Dog must implement method doYourJob() from interface Guard.

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JAVA Interfaces and Abstract Classes
Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a default constructor. Which of the following is correct?1. A a = new A();2. A a = new B();3. B b = new A();4. B b = new B();

1 and 2

2 and 4

2 and 3

1 and 3

3 and 4

1 and 2

2 and 4

2 and 3

1 and 3

3 and 4

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JAVA Interfaces and Abstract Classes
What will be the output?1. public interface InfA{2. protected String getName();3. }public class Test implements InfA{ public String getName(){ return "test-name"; } public static void main (String[] args){ Test t = new Test(); System.out.println(t.getName()); }}

test-name

Compilation fails due to an error on lines 2

None of these

Compilation succeed but Runtime Exception

Compilation fails due to an error on lines 1

test-name

Compilation fails due to an error on lines 2

None of these

Compilation succeed but Runtime Exception

Compilation fails due to an error on lines 1

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JAVA Interfaces and Abstract Classes
interface Base{ boolean m1 (); byte m2(short s);}which two code fragments will compile?1. interface Base2 implements Base {}2. abstract class Class2 extends Base { public boolean m1(){ return true; }}3. abstract class Class2 implements Base {}4. abstract class Class2 implements Base { public boolean m1(){ return (7 > 4); }}5. abstract class Class2 implements Base { protected boolean m1(){ return (5 > 7) }}

3 and 4

2 and 3

1 and 2

1 and 3

4 and 5

3 and 4

2 and 3

1 and 2

1 and 3

4 and 5

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JAVA Interfaces and Abstract Classes
In Java, declaring a class abstract is useful

When it makes sense to have objects of that class.

When default implementations of some methods are not desirable.

To force developers to extend the class not to use its capabilities.

When it doesn't make sense to have objects of that class.

To prevent developers from further extending the class.

When it makes sense to have objects of that class.

When default implementations of some methods are not desirable.

To force developers to extend the class not to use its capabilities.

When it doesn't make sense to have objects of that class.

To prevent developers from further extending the class.

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JAVA Interfaces and Abstract Classes
Runnable is a _____ .

interface

method

class

vaiable

abstract class

interface

method

class

vaiable

abstract class

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JAVA Interfaces and Abstract Classes

JAVA Interfaces and Abstract Classes Given the following piece of code:public interface Guard{ void doYourJob();}abstract public class Dog implements Guard{ }which of the following statements is correct?

JAVA Interfaces and Abstract Classes Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a default constructor. Which of the following is correct?1. A a = new A();2. A a = new B();3. B b = new A();4. B b = new B();

JAVA Interfaces and Abstract Classes What will be the output?1. public interface InfA{2. protected String getName();3. }public class Test implements InfA{ public String getName(){ return "test-name"; } public static void main (String[] args){ Test t = new Test(); System.out.println(t.getName()); }}

JAVA Interfaces and Abstract Classes In Java, declaring a class abstract is useful

JAVA Interfaces and Abstract Classes Runnable is a _____ .

JAVA Interfaces and Abstract Classes
Given the following piece of code:public interface Guard{ void doYourJob();}abstract public class Dog implements Guard{ }which of the following statements is correct?

JAVA Interfaces and Abstract Classes
Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a default constructor. Which of the following is correct?1. A a = new A();2. A a = new B();3. B b = new A();4. B b = new B();

JAVA Interfaces and Abstract Classes
What will be the output?1. public interface InfA{2. protected String getName();3. }public class Test implements InfA{ public String getName(){ return "test-name"; } public static void main (String[] args){ Test t = new Test(); System.out.println(t.getName()); }}

JAVA Interfaces and Abstract Classes
In Java, declaring a class abstract is useful

JAVA Interfaces and Abstract Classes
Runnable is a _____ .