JAVA Interfaces and Abstract Classes In Java, declaring a class abstract is useful When default implementations of some methods are not desirable. When it doesn't make sense to have objects of that class. When it makes sense to have objects of that class. To prevent developers from further extending the class. To force developers to extend the class not to use its capabilities. When default implementations of some methods are not desirable. When it doesn't make sense to have objects of that class. When it makes sense to have objects of that class. To prevent developers from further extending the class. To force developers to extend the class not to use its capabilities. ANSWER DOWNLOAD EXAMIANS APP
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 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. ANSWER DOWNLOAD EXAMIANS APP
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 in the declaration of class Dog we must use the keyword extends instead of implements. This code will not compile, because method doYourJob() in interface Guard must be defined abstract. This code will not compile, because class Dog must implement method doYourJob() from interface Guard. 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 method doYourJob() in interface Guard must be defined abstract. This code will not compile, because class Dog must implement method doYourJob() from interface Guard. This code will compile without any errors. ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes Which of the following class definitions defines a legal abstract class? public class abstract A { abstract void unfinished(); } class A { abstract void unfinished() { } } class A { abstract void unfinished(); } abstract class A { abstract void unfinished(); } public class abstract A { abstract void unfinished(); } class A { abstract void unfinished() { } } class A { abstract void unfinished(); } abstract class A { abstract void unfinished(); } ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes What will be the output?interface A{public void method();}class One{public void method(){System.out.println("Class One method");}}class Two extends One implements A{public void method(){System.out.println("Class Two method");}}public class Test extends Two{public static void main(String[] args){A a = new Two();a.method();}} Compilation Error None of these will print Class One method will print Class Two method compiles fine but print nothing Compilation Error None of these will print Class One method will print Class Two method compiles fine but print nothing ANSWER DOWNLOAD EXAMIANS APP
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); }} Successful run and print 37 None of these Runtime error Compilation error due to line 2 Compilation error due to line 1 Successful run and print 37 None of these Runtime error Compilation error due to line 2 Compilation error due to line 1 ANSWER DOWNLOAD EXAMIANS APP
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