Mistakes

Question 1

Does it compile?

int num =0, num2=0;

Answer 1

Yes

Question 2

public static void main(String[] args) {

	String chair, table = "metal";
	chair = chair+table;
	System.out.println(chair);
}

Answer 2

DNC bc local variable is not initialzed and they dont have the default value.

Question 3

double chair = 8.0f;
System.out.println(chair);

Answer 3

runs fine

Question 4

public static String convert(Integer value) {
return value.toString();
}

public static String convert(int value) {
	return value.toString();
}

public static String convert(Object value) {
	return value.toString();
}

Answer 4

yes
DNC
yes

Question 5

What can you put to have d=0?
short, double, int, byte?
public static void main(String[] args) {
____ d;
System.out.println(d);

}

Answer 5

DNC because local variables does not have a default value

Question 6

What can you put to have d=0?
double d;
public static void main(String[] args) {
System.out.println(d);
}

Answer 6

DNC

Question 7

What will be the output?
public class Birthday {
double d;
public static void main(String[] args) {
Birthday d = new Birthday();
System.out.println(d.d);
}

Answer 7

0.0

Question 8

finalize() method memorize how it may be called?

Answer 8

It may be callled zero or one times

Question 9

int Integer =1;
int String = 1;
System.out.println(Integer);

Answer 9

1, compiles both cases.

Question 10

Will this compile?
public static void main(String[] args) {
Double d = new Double(100);
double dd = new Double(100);
}

Answer 10

yes
you can convert a primitive to wrapper class object simply by assigning it.

Question 11

Can you force garbage collection to occur at certain point?

Answer 11

never.

Question 12

parseInt() is used with which primitive or reference?

Answer 12

primitive

Question 13

valueOf() is used with which? primitive or reference?

Answer 13

reference

Question 14

String message = 11>10? “Greagt”:false;

Answer 14

dnc

Question 15

String a =null;
int b = 2;
System.out.println(a==b);

Answer 15

DNC

Question 16

Can you use native with abstract ?

Answer 16

never

Question 17

Conversion from short to char needs a cast.

Answer 17

true. reverse is true.

Question 18

final int k = 10; byte b = k;

Answer 18

yes. its called implicit narrowing.

Question 19

Which of the following are correct about java.util.function.Predicate?

Answer 19

It is an interface that has only one abstract method (among other non-abstract methods) with the signature - public boolean test(T t);