Objective type questions on interface in java and answers
(1)
(1)
interface Apple{
float cost=9.5f;
public void display();
}
class Try implements Apple{
public static void main(String[] args){
Try t=new Try();
t.display();
}
public void display(){
System.out.print("cost of apple is :"+cost);
}
}
What will output when you compile and run the above code?
(a) cost of apple is :9.5
(b) cost of apple is :0.0
(c) cost of apple is :9.5f
(d)Compiler error
Answer: (a)
(2)
interface Inf{
double a,b;
public void add(double p,double q);
}
class Try implements Inf{
public static void main(String[] args){
Try t=new Try();
t.add(11.0,22.0);
}
public void add(double p,double q){
a=p;
b=q;
System.out.print(a+b);
}
}
What will output when you compile and run the above code?
(a)11.0
(b)22.0
(c)33.0
(d)Compiler error
Answer: (d)
(3)
interface Inf{
public long add(int p,int q);
public void display(long sum){
Systm.out.print(sum);
}
}
class Try implements Inf{
public static void main(String[] args){
Try t=new Try();
long sum=t.add(130,120);
t.display(sum);
}
public long add(int p,int q){
return p+q;
}
}
What will output when you compile and run the above code?
(a)130
(b)120
(c)250
(d)Compiler error
Answer: (d)
(4)
interface Inf{
long cal(int p);
}
class Try implements Inf{
public static void main(String[] args){
Try t=new Try();
long sum=t.cal(25);
System.out.print(sum);
}
long cal(int p){
return p++;
}
}
What will output when you compile and run the above code?
(a)25
(b)26
(c)27
(d)Compiler error
Answer: (d)
(5)
interface Inf{
int a=5;
}
class Test{
int b;
}
class Try extends Test implements Inf{
public static void main(String[] args){
Try t=new Try();
System.out.print(a+t.b);
}
}
What will output when you compile and run the above code?
(a)5
(b)10
(c)Garbage value
(d)Compiler error
Answer: (a)
(6)
class Test{
int a=0;
protected interface Ni{
short calculation(int p);
}
}
class Try extends Test implements Test.Ni{
public static void main(String[] args){
Try t=new Try();
short val=t.calculation(t.a);
System.out.print(val);
}
public short calculation(int p){
for(int i=0;i<2;i++){
int a=2;
++a;
}
return (short)(a+p);
}
}
What will output when you compile and run the above code?
(a)0
(b)3
(c)4
(d)Compiler error
Answer: (a)
(7)
class Mango{
final int a=5;
}
class Fruit extends Mango {
final int a=10;
}
class DynamicDispatch extends Fruit{
final int a=20;
public static void main(String[] args){
Mango m=new DynamicDispatch();
Fruit f=new DynamicDispatch();
System.out.print(m.a|f.a);
}
}
What will be output of above program?
(a)15
(b)20
(c)30
(d)Compiler error
Answer: (a)
(8)
class Mango{
final int a=5;
}
class Fruit extends Mango {
final int a=10;
}
class DynamicDispatch extends Fruit{
final int a=15;
public static void main(String[] args){
DynamicDispatch t=new Mango();
System.out.print(t.a);
}
}
What will be output of above program?
(a)5
(b)10
(c)15
(d)Compiler error
Answer: (d)
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