Interfaces And Abstract Classes - Study Mode
[#216] What will be the output of the following Java program? class Output
{
public static void main(String args[])
{
String str = "TRUE"
boolean x = Boolean.valueOf(str)
System.out.print(x)
}
}
Correct Answer
(A) True
(E) True
[#217] Which of the following is method of wrapper Integer for converting the value of an object into int?
Correct Answer
(B) int intValue()
[#218] Will this Java program generate same output is executed again? class Output
{
public static void main(String args[])
{
int y = double z = Math.random()
System.out.print(y)
}
}
Correct Answer
(B) No
[#219] What will be the output of the following Java program? class Output
{
public static void main(String args[])
{
String str = "true false true"
boolean x = Boolean.valueOf(str)
System.out.print(x)
}
}
Correct Answer
(B) False
[#220] 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) }}
Correct Answer
(C) 3 and 4
Explanation
Solution: (3) is correct because an abstract class doesn't have to implement any or all of its interface's methods. (4) is correct because this method is correctly implemented ((7 > 4) is a boolean). (1) is incorrect because interfaces doesn't implement anything. (2) is incorrect because classes don't extend interfaces. (5) is incorrect because interface methods are implicitly public, so the methods being implemented must be public.