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Which among the following best describes abstract classes?

Which among the following best describes abstract classes? Correct Answer If a class has at least one pure virtual function, it’s abstract class

The condition for a class to be called abstract class is that it must have at least one pure virtual function. The keyword abstract must be used while defining abstract class in java.

Related Questions

Which of the following is/are true for an abstract class? i) Abstract classes in PHP are declared with the help of abstract keyword. ii) A class is declare abstract by using the keyword implements. iii) It is a class that really isn’t supposed to ever be instantiated but instead serves as a base class. iv) Attempting to instantiate an abstract class results in an error.
Which of the following is/are true for an abstract class?
1. A class is declared abstract by prefacing the definition with the word abstract.
2. A class is declare abstract by using the keyword implements.
3. It is a class that really isn’t supposed to ever be instantiated but instead serves as a base class.
4. Attempting to instantiate an abstract class results in an error.
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 {} 
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) }}
Which two classes use the Shape class correctly?
A. public class Circle implements Shape { private int radius; }B. public abstract class Circle extends Shape { private int radius; }C. public class Circle extends Shape { private int radius; public void draw(); }D. public abstract class Circle implements Shape { private int radius; public void draw(); }E. public class Circle extends Shape { private int radius; public void draw() { /* code here */ } }F. public abstract class Circle implements Shape { private int radius; public void draw() { /* code here */ } }
Read the given statements carefully. Assuming that the information given in the statements is true, decide which of the given conclusions is based on the Statements. Statements: 1. Ram goes to mathematics class on Monday. 2. He attends literature classes on Friday. 3. He goes to guitar classes the day before he goes to history classes. 4. He attends history classes 2 days before literature classes.
What is the output of following program? abstract class Sum { public abstract int sumOfTwo(int n1, int n2); public abstract int sumOfThree(int n1, int n2, int n3); public void disp( ){ System.out.println("Method of class Sum"); } } class DemoAbstract1 extends Sum { public int sumOfTwo(int num1, int num2) { return num1+num2; } public int sumOfThree(int num1, int num2, int num3) { return num1+num2+num3; } public static void main(String args[ ]){ Sum obj = new DemoAbstract1( ); System.out.println(obj.sumOfTwo(3, 7)); System.out.println(obj.sumOfThree(4, 3, 19)); obj.disp( ); } }
Which of the following declaration is illegal? = “Best C programming classes by Sanfoundry”; c) char str = “Best C programming classes by Sanfoundry”; d) char str = “Best C programming classes by Sanfoundry”;
public abstract class Shape { private int x; private int y; public abstract void draw(); public void setAnchor(int x, int y) { this.x = x; this.y = y; } } Which two classes use the Shape class correctly?
Consider the following statements: 1. The classes of type 15-19, 20-24, 25-29 etc. are exclusive classes. 2. The classes of type 15-20, 20-25, 25-30 etc. are inclusive classes. Which of the above statements is/are correct?