Which two of the following are legal declarations for abstract classes and interfaces?1. final abstract class Test {}2. public static interface Test {}3. final public class Test {}4. protected abstract class Test {}5. protected interface Test {}6. abstract public class Test {}

JAVA Interfaces and Abstract Classes
Which two of the following are legal declarations for abstract classes and interfaces?1. final abstract class Test {}2. public static interface Test {}3. final public class Test {}4. protected abstract class Test {}5. protected interface Test {}6. abstract public class Test {}

3 and 6

5 and 6

2 and 4

1 and 2

3 and 5

3 and 6

5 and 6

2 and 4

1 and 2

3 and 5

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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 3

3 and 4

2 and 3

1 and 2

2 and 4

1 and 3

3 and 4

2 and 3

1 and 2

2 and 4

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JAVA Interfaces and Abstract Classes
Which of the following declares an abstract method in an abstract Java class?

public abstract method();

public abstract void method();

public abstract void method() {}

public void method() {}

public void abstract Method();

public abstract method();

public abstract void method();

public abstract void method() {}

public void method() {}

public void abstract Method();

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JAVA Interfaces and Abstract Classes
Determine output of the following code.interface A { }class C { }class D extends C { }class B extends D implements A { }public class Test extends Thread{ public static void main(String[] args){ B b = new B(); if (b instanceof A) System.out.println("b is an instance of A"); if (b instanceof C) System.out.println("b is an instance of C"); }}

b is an instance of A followed by b is an instance of

b is an instance of

Nothing.

b is an instance of

b is an instance of A followed by b is an instance of

b is an instance of

Nothing.

b is an instance of

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JAVA Interfaces and Abstract Classes
Which of the following statements regarding abstract classes are true?

All of these

An abstract class can be extended.

An abstract class can be used as a data type.

A subclass can override a concrete method in a superclass to declare it abstract.

A subclass of a non-abstract superclass can be abstract.

All of these

An abstract class can be extended.

An abstract class can be used as a data type.

A subclass can override a concrete method in a superclass to declare it abstract.

A subclass of a non-abstract superclass can be abstract.

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JAVA Interfaces and Abstract Classes
interface Test{ int p = 10; //line 1 public int q = 20; //line 2 public static int r = 30; //line 3 public static final int s = 40; //line 4}Which of the above line will give compilation error?

1

4

None of these

2

3

1

4

None of these

2

3

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JAVA Interfaces and Abstract Classes

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 Which of the following declares an abstract method in an abstract Java class?

JAVA Interfaces and Abstract Classes Which of the following statements regarding abstract classes are true?

JAVA Interfaces and Abstract Classes interface Test{ int p = 10; //line 1 public int q = 20; //line 2 public static int r = 30; //line 3 public static final int s = 40; //line 4}Which of the above line will give compilation error?

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
Which of the following declares an abstract method in an abstract Java class?

JAVA Interfaces and Abstract Classes
Which of the following statements regarding abstract classes are true?

JAVA Interfaces and Abstract Classes
interface Test{ int p = 10; //line 1 public int q = 20; //line 2 public static int r = 30; //line 3 public static final int s = 40; //line 4}Which of the above line will give compilation error?