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) }}

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) }}

1 and 2

2 and 3

3 and 4

1 and 3

4 and 5

1 and 2

2 and 3

3 and 4

1 and 3

4 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();

2 and 3

1 and 3

1 and 2

3 and 4

2 and 4

2 and 3

1 and 3

1 and 2

3 and 4

2 and 4

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JAVA Interfaces and Abstract Classes
Which of the following class definitions defines a legal abstract class?

public class abstract A { abstract void unfinished(); }

abstract class A { abstract void unfinished(); }

class A { abstract void unfinished() { } }

class A { abstract void unfinished(); }

public class abstract A { abstract void unfinished(); }

abstract class A { abstract void unfinished(); }

class A { abstract void unfinished() { } }

class A { abstract void unfinished(); }

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

All of these

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

An abstract class can be used as a data type.

An abstract class can be extended.

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

All of these

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

An abstract class can be used as a data type.

An abstract class can be extended.

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

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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 compile without any errors.

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

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 compile without any errors.

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

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

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JAVA Interfaces and Abstract Classes
What will happen after compiling this program code?abstract class MyClass{ //line 1 private int a, b; public void call(int a, int b){ this.a = a; this.b = b; System.out.print(a+b); }}public class Test{ public static void main(String args[]){ MyClass m = new MyClass(); //line 2 m.call(12,25); }}

Compilation error due to line 2

Compilation error due to line 1

Runtime error

None of these

Successful run and print 37

Compilation error due to line 2

Compilation error due to line 1

Runtime error

None of these

Successful run and print 37

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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 class definitions defines a legal abstract class?

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

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
Which of the following class definitions defines a legal abstract class?

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

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?