JAVA Interfaces and Abstract Classes
Given the following piece of code:public class School{ public abstract double numberOfStudent();}which of the following statements is true?

You must add a return statement in method numberOfStudent().
The method numberOfStudent() in class School must have a body.
Class School must be defined abstract.
The keywords public and abstract cannot be used together.

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JAVA Interfaces and Abstract Classes
What will be the output when the following program is compiled and executed?abstract class TestAbstract{ String my_name; String myName(){ my_name = "Examveda"; return my_name; } abstract void display();}public class Test extends TestAbstract{ void display(){ String n = myName(); System.out.print("My name is "+ n); } public static void main(String args[]){ Test t = new Test(); t.display(); }}

Program compiles but leads to runtime exception.
Compilation error as class can not be declared as abstract.
Compilation error occurs as the abstract class TestAbstract contains a non-abstract method.
None of these
Program will compile and execute successfully and prints

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

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

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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()); }}

None of these
test-name
Compilation fails due to an error on lines 2
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) }}

2 and 3
1 and 2
4 and 5
1 and 3
3 and 4

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