1-
import java.util.*;
class GenDemo1 {
public static void main(String... args) {
List<? super String> list1 = new ArrayList<Object>();
list1.add(new String()); //Line 1
list1.add(new Object()); //Line 2
}
}
2-
import java.util.*;
class Person implements Comparable<Person> {
String name;
Person() {}
Person(String name) {this.name =name;}
public int compareTo(Person p1) {
return name.compareTo(p1.name);
}
}
class Manager extends Person {
}
//Insert code here
public void add(T item) {
}
}
class GenDemo2 {
public static void main(String... args) {
MyList<Person> list1 = new MyList<Person>();
MyList<Manager> list2 = new MyList<Person>();
}
}
What inserted independently at the marked location will allow the code to compile and run well.
(Choose all that apply)
A- class MyList<T extends Comparable<T>> {
B- class MyList<T extends Comparable> {
C- class MyList<T extends Comparable<? super T>> {
D- class MyList<T extends Comparable<? extends T>> {
E- class MyList<T> {
F- class MyList<?> {
G- class MyList<? extends Comparable> {
H- class MyList<T extends Comparable<?> {
3-
1. import java.util.*;
2. public class Fruits {
3. public static void main(String [] args) {
4. Set c1 = new TreeSet();
5. Set o1 = new TreeSet();
6. bite(c1);
7. bite(o1);
8. }
9. // insert code here
10. }
11. class Citrus { }
12. class Orange extends Citrus { }
Which, inserted independently at line 9, will compile? (Choose all that apply.)
A: static void bite(Set<?> st1){}
B: static void bite(Set<? extends Citrus> st1){}
C: static void bite(Set<? extends Orange> st1){}
D: static void bite(Set<Object> st1){}
E: static void bite(Set<? extends Object> st1){}
F: static void bite(Set<? extends Fruits> st1){}
G: public static void bite(Set<Object> s) { }
4-
1. import java.util.*;
2. public class Fruits {
3. public static void main(String [] args) {
4. Set<Citrus> c1 = new TreeSet();
5. Set<Citrus> o1 = new TreeSet();
6. bite(c1);
7. bite(o1);
8. }
9. // insert code here
10. }
11. class Citrus { }
12. class Orange extends Citrus { }
Which, inserted independently at line 9, will compile? (Choose all that apply.)
A: static void bite(Set<Citrus> st1){}
B: static void bite(Set<? super Citrus> st1){}
C: static void bite(Set<? extends java.io.Serializable> st1){}
D: public static void bite(Set<Object> s) { }
E: static void bite(Set<? extends Comparable> st1){}
F: static void bite(Collection col){}
G: static void bite(Collection<? extends Citrus> st1){}
H: static void bite(Object st1){}
5-
import java.util.*;
public class DemoGen {
public static void main(String... args) {
List<? extends Number> list1 = new ArrayList<Integer>(); //Line1
list1.add(new Integer(10)); //Line 2
}
}
A: Compilation fails at line 1
B: Compilation fails at line 2
C: Compiles and runs fins
D: Compiles but run time exception
6-
import java.util.*;
public class DemoGen {
public static void main(String... args) {
List<? super Number> list1 = new ArrayList<Object>(); //Line 1
list1.add(new Integer(10)); //Line 2
list1.add(12); //Line 3
list1.add(120.01f); //Line 4
}
}
A: Compilation fails at line 3
B: Compilation fails at line 4
C: Multiple compile error
D: Compiles and runs fins
E: Compiles but run time exception
7-
import java.util.*;
public class DemoGen {
public static void main(String... args) {
List list1 = new ArrayList<Integer>(); //Line 1
list1.add(12);
list1.add(13);
list1.add(14);
list1.add(15);
for(Integer x : list1) {
System.out.print(x + ",");
}
}
}
A: Prints 12,13,14,15
B: Compilation fails due to error at Line 1
C: Comlilation fails
D: Compiles but run time exception
E: None of the above
8-
import java.util.*;
public class DemoGen {
public static void main(String... args) {
Set list = new TreeSet<Integer>(); //Line 1
list1.add(15);
list1.add(12);
list1.add(new String("13e")); //Line 2
list1.add(14);
for(Integer x : list1) { // Line 3
System.out.print(x + ",");
}
}
}
A: Compilation fails due to error at Line 1
B: Compilation fails due to error at Line 2
B: Compilation fails due to error at Line 3
C: Line 1 and Line 2 cause compilation error
D: Compiles fine but run time exception
E: Compiles and runs fine and prints 12,13,14,15
9-
import java.util.*;
public class DemoGen {
public static void main(String... args) {
Set<Integer> list = new TreeSet(); //Line 1
list1.add(14);
list1.add(15);
list1.add(12);
list1.add(new Integer("13")); //Line 2
for(Integer x : list1) { // Line 3
System.out.print(x + ",");
}
}
}
A: Compilation fails due to error at Line 1
B: Compilation fails due to error at Line 2
B: Compilation fails due to error at Line 3
C: Line 1 and Line 2 cause compilation error
D: Compiles fine but run time exception
E: Compiles and runs fine and prints 12,13,14,15
10-
import java.util.*;
public class DemoGen {
public static void main(String... args) {
Set list = new TreeSet(); //Line 1
list1.add(14.12f);
list1.add(15.01);
list1.add(1.21);
list1.add(new Integer("13")); //Line 2
for(Object x : list1) { // Line 3
System.out.print(x + ",");
}
}
}
A: Compilation fails due to error at Line 1
B: Compilation fails due to error at Line 2
B: Compilation fails due to error at Line 3
C: Line 1 and Line 2 cause compilation error
D: Compiles fine but run time exception
E: Compiles and runs fine and prints 12,13,14,15
11-
public class Employee implements Comparable {
String name;
private Employee(String name){
this.name = name;
}
public int compareTo(Employee e1) {
return name.compareTo(e1.name);
}
}
A: Compiles fine
B: Compiler error due to failing contract of interface implementation
C: Compiler error because constructor can't be private
C: compiler error because public class must have a main() method to compile the code
D: Compiles with an exception