Given the code. What is the output?
public class Test {
int a = 10;
public void doStuff(int a) {
a += 1;
System.out.println(++a);
}
public static void main(String args[]) {
Test t = new Test();
t.doStuff(3);
}
}
0/p : 5
------------------------------------------------------------------
Given the code. What is the result?
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
public class HashTest {
private String str;
public HashTest(String str) {
this.str = str;
}
@Override
public String toString() {
return this.str;
}
public static void main(String args[]) {
HashTest h1 = new HashTest("2");
String s1 = new String("1");
List<Object> list = new LinkedList<Object>();
list.add(h1);
list.add(s1);
Collections.sort(list);
for (Object o : list) {
System.out.print(o + " ");
}
}
}
A) "2 1" is printed.
B) "1 2" is printed.
C) Compilation fails.
D) An exception is thrown at runtime
o/p :
-----------------------------------------------------------------
Given the code. What is the result?
public static void main(String args[]) {
String str = "null";
if (str == null) {
System.out.print("1");
} else if (str.length() == 0) {
System.out.print("2");
} else {
System.out.print("3");
}
}
A) Compilation fails.
B) "1" is printed.
C) "2" is printed.
D) "3" is printed.
E) An exception is thrown at runtime.
--------------------------------------------------------------
What should be called after the code below to suggest that the JVM expend effort toward recycling the memory used by the object a? (Select two)
BigObject a = MyFactory.createBigObject();
a.doStuff();
a = null;
A) System.gc()
B) Runtime.gc()
C) System.freeMemory()
D) Runtime.getRuntime().freeMemory()
E) Runtime.getRuntime().gc()
--------------------------------------------------------------
class Hotel {
public void book() throws Exception {
throw new Exception();
}
}
public class SuperHotel extends Hotel {
public void book() {
System.out.print("booked");
}
public static void main(String args[]) {
Hotel h = new SuperHotel();
h.book();
}
}
A) An exception is thrown at runtime.
B) Compilation fails.
C) The code runs without any output.
D) "boked" is printed.
------------------------------------------------------------
class Hotel {
public void book() throws Exception {
throw new Exception();
}
}
public class SuperHotel extends Hotel {
public void book() {
System.out.print("booked");
}
public static void main(String args[]) {
Hotel h = new SuperHotel();
h.book();
}
}
-----------------------------------------------------------
Given the code. What is the result?
public class Test {
private static void doStuff(String str) {
int var = 4;
if (var == str.length()) {
System.out.print(str.charAt(var--) + " ");
}
else {
System.out.print(str.charAt(0) + " ");
}
}
public static void main(String args[]) {
doStuff("abcd");
doStuff("efg");
doStuff("hi");
}
}
A) Compilation fails.
B) An exception is thrown at runtime.
C) d e h
D) d f i
E) c f i
F) c e h
--------------------------------------------------------
Given the code. Which statements are true? (Select two)
public class Hotel {
public static void book() {
//some code goes here
}
public void cancelBooking() {
//some code goes here
}
}
A) Method book() can directly call method cancelBooking()
B) Method cancelBooking() can directly call method book()
C) Hotel.book() is a valid invocation of book()
D) Hotel.cancelBooking() is a valid invocation of cancelBooking()
expalnation :
public class StaticEx1 {
public static void book() {
// cancelBooking();
}
public void cancelBooking() {
//some code goes here
}
}
if we call method cancelBooking in book() method we will get the following output:
StaticEx1.java:4: non-static method cancelBooking() cannot be referenced from a
static context
cancelBooking();
^
1 error
so Correct answer is
public class StaticEx1 {
public static void book() {
}
public void cancelBooking() {
//some code goes here
book();
}
}
i.e we can call a static method in non static context. But not a non-static method in static context.
class StaticEx {
public static void book() {
// cancelBooking();
System.out.println(" Hi! I am a static method ");
}
public void cancelBooking() {
//some code goes here
book();
System.out.println(" Hi! I am a non-static method ");
}
}
class StaticEx1
{
public static void main(String[] args)
{
StaticEx.book();
// StaticEx.cancelBooking(); //a non-static method cannot be referenced from a static context.
}
}
------------------------------------------------------------------
Given the code. What is the result?
public class Cruiser implements Runnable {
public static void main(String[] args) {
Thread a = new Thread(new Cruiser());
a.start();
System.out.print("Begin");
a.join();
System.out.print("End");
}
public void run() {
System.out.print("Run");
}
}
A) Compilation fails.
B) An exception is thrown at runtime.
C) "BeginRunEnd" is printed.
D) "BeginEndRun" is printed.
E) "BeginEnd" is printed.
-----------------------------------------------------------------
public class TryMe {
public static void printB(String str) {
System.out.print(Boolean.valueOf(str) ? "true" : "false");
}
public static void main(String args[]) {
printB("tRuE");
printB("false");
}
}
-------------------------------------------------------------------
Given the code. What is the result?
public static void main(String args[]) {
String str = null;
if (str == null) {
System.out.print("1");
} else (str.length() == 0) {
System.out.print("2");
} else {
System.out.print("3");
}
}
A) Compilation fails.
B) "1" is printed.
C) "2" is printed.
D) "3" is printed.
E) An exception is thrown at runtime.
-----------------------------------------------------------------
Given the code. What is the result?
public class Hotel {
private static void book() {
System.out.print("book");
}
public static void main(String[] args) {
Thread.sleep(1);
book();
}
}
A) Compilation fails.
B) An exception is thrown at runtime.
C) "book" is printed.
D) The code executes normally, but nothing is printed.
----------------------------------------------------------------
import java.util.HashSet;
public class HashTest {
private String str;
public HashTest(String str) {
this.str = str;
}
@Override
public int hashCode() {
return this.str.hashCode();
}
@Override
public boolean equals(Object obj) {
return this.str.equals(obj);
}
public static void main(String args[]) {
HashTest h1 = new HashTest("1");
HashTest h2 = new HashTest("1");
String s1 = new String("2");
String s2 = new String("2");
HashSet<Object> hs = new HashSet<Object>();
hs.add(h1);
hs.add(h2);
hs.add(s1);
hs.add(s2);
System.out.print(hs.size());
}
}
)
A)"4" is printed.
B) "3" is printed.
C) "2" is printed.
D) Compilation fails.
E) An exception is thrown at runtime.
------------------------------------------------------------------------
Given the code. What is the result?
public static void main(String args[]) {
try {
String arr[] = new String[10];
arr = null;
arr[0] = "one";
System.out.print(arr[0]);
} catch(NullPointerException nex) {
System.out.print("null pointer exception");
} catch(Exception ex) {
System.out.print("exception");
}
}
A) "one" is printed.
B) "exception" is printed.
C) "null pointer exception" is printed. // correct answer
D) Compilation fails.
-----------------------------------------------------------------------
.
Which of the following lines will print false?
1.public class MyClass
2.{
3. static String s1 = "I am unique!";
4. public static void main(String[] args)
5. {
6. String s2 = "I am unique!";
7. String s3 = new String(s1);
8. System.out.println(s1 == s2);
9. System.out.println(s1.equals(s2));
10. System.out.println(s3 == s1);
11. System.out.println(s3.equals(s1));
12. }
13.}
a. Line 8
b. Line 9
c. Line 10
d. Line 11
e. None of these
-------------------------------------------------------------------
Given the code. What is the result?
import java.util.Collections;
import java.util.LinkedList;
public class TryMe {
public static void main(String args[]) {
LinkedList<String> list = new LinkedList<String>();
list.add("BbB1");
list.add("bBb2");
list.add("bbB3");
list.add("BBb4");
Collections.sort(list);
for (String str : list) {
System.out.print(str + ":");
}
}
}
A) "BbB1:bBb2:bbB3:BBb4:" is printed.
B) "BBb4:bbB3:bBb2:BbB1:" is printed.
C) "BBb4:BbB1:bBb2:bbB3:" is printed. // correct answer
D) "bbB3:bBb2:BbB1:BBb4:" is printed
E) Compilation fails.
F) An exception is thrown at runtime.
--------------------------------------------------------------------
Give the code. What is the result?
class Hotel {
public int bookings;
public void book() {
bookings++;
}
}
public class SuperHotel extends Hotel {
public void book() {
bookings--;
}
public void book(int size) {
book();
super.book();
bookings += size;
}
public static void main(String args[]) {
SuperHotel hotel = new SuperHotel();
hotel.book(2);
System.out.print(hotel.bookings);
}
}
A) Compilation fails.
B) An exception is thrown at runtime.
C) 0
D) 1
E) 2
F) -1
-----------------------------------------------------------------------------
Given the code. What is the result?
public class Cruiser implements Runnable {
public void run() {
System.out.print("go");
}
public static void main(String arg[]) {
Thread t = new Thread(new Cruiser());
t.run();
t.run();
t.start();
}
}
A) Compilation fails.
B) An exception is thrown at runtime.
C) "go" is printed
D) "gogogo" is printed // cORRECT ANSWER
E) "gogo" is printed
================================================================================
Given the code. What is the result?
class Small {
public Small() {
System.out.print("a ");
}
}
class Small2 extends Small {
public Small2() {
System.out.print("b ");
}
}
class Small3 extends Small2 {
public Small3() {
System.out.print("c ");
}
}
public class Test {
public static void main(String args[]) {
new Small3();
}
}
A) a
B) c
C) a b c
D) c b a
E) The code runs without output.
---------------------------------------------------------------------------------
class Test2{
public static void main(String args[]) {
Object myObj = new String[]{"one", "two", "three"};
{
for (String s : (String[])myObj) System.out.print(s + ".");
}
}
}
o/p : Error at line 3 or one.two.three if declaration is ended with semicoaln in line 3.
----------------------------------------------------------------------------------
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
public class TryMe3 {
public static void main(String args[]) {
List list = new LinkedList<String>();
list.add("one");
list.add("two");
list.add("three");
Collections.reverse(list);
Iterator iter = list.iterator();
for (Object o : list) {
System.out.print(o + " ");
}
// System.out.println(iter);
}
}
three two one is output
-------------------------------------------------------------------------------
Given the code. What is the result?
import java.io.*;
public class Hotel implements Serializable {
private transient Room room = new Room();
public static void main(String[] args) {
Hotel h = new Hotel();
try {
FileOutputStream fos = new FileOutputStream("Hotel.dat");
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(h);
oos.close();
} catch(Exception ex) {
ex.printStackTrace();
}
}
}
class Room {
}
A) Compilation fails.
B) An exception is thrown at runtime.
C) An instance of Hotel is serialized.
D) An instance of Hotel and an instance of Room are both serialized.
-----------------------------------------------------------------------------
Give a piece of code. Which two are possible results? (Select two)
public class Cruiser {
private int a = 0;
public void foo() {
Runnable r = new LittleCruiser();
new Thread(r).start();
new Thread(r).start();
}
public static void main(String arg[]) {
Cruiser c = new Cruiser();
c.foo();
}
public class LittleCruiser implements Runnable {
public void run() {
int current = 0;
for (int i = 0; i < 4; i++) {
current = a;
System.out.print(current + ", ");
a = current + 2;
}
}
}
}
A) 0, 2, 4, 0, 2, 4, 6, 6,
B) 0, 2, 4, 6, 8, 10, 12, 14,
C) 0, 2, 4, 6, 8, 10, 2, 4,
D) 0, 0, 2, 2, 4, 4, 6, 6, 8, 8, 10, 10, 12, 12, 14, 14,
E) 0, 2, 4, 6, 8, 10, 12, 14, 0, 2, 4, 6, 8, 10, 12, 14,
===============================================================================
package com.mycompany;
public class Hotel {
public int roomNr = 100;
}
A) Only the Hotel class.
B) Any class.
C) Any class in com.mycompany package.
D) Any class that extends Hotel.
--------------------------------------------------------------------------------
Given the exhibit. What is the result?
public class Hotel {
public static void book(short a) {
System.out.print("short ");
}
public static void book(Short a) {
System.out.print("SHORT ");
}
public static void book(Long a) {
System.out.print("LONG ");
}
public static void main(String[] args) {
short shortRoom = 1;
int intRoom = 2;
book(shortRoom);
book(intRoom);
}
}
A) SHORT LONG
B) short LONG
C) Compilation fails
D) An exception is thrown at runtime
-----------------------------------------------------------------------------
Given the code. What is the output?
public class Hotel {
private int roomNr;
public Hotel(int roomNr) {
this.roomNr = roomNr;
}
public int getRoomNr() {
return this.roomNr;
}
static Hotel doStuff(Hotel hotel) {
hotel = new Hotel(1);
return hotel;
}
public static void main(String args[]) {
Hotel h1 = new Hotel(100);
System.out.print(h1.getRoomNr() + " ");
Hotel h2 = doStuff(h1);
System.out.print(h1.getRoomNr() + " ");
System.out.print(h2.getRoomNr() + " ");
h1 = doStuff(h2);
System.out.print(h1.getRoomNr() + " ");
System.out.print(h2.getRoomNr() + " ");
}
}
A) 100 1 1 1 1
B) 100 100 1 1 1
C) 100 100 100 1 1
D) 100 100 100 100 1
E) 100 100 100 100 100
-------------------------------------------------------------------------
Given the code. What is the result?
public class Test {
private static void doStuff(String str) {
int var = 4;
if (var == str.length()) {
System.out.print(str.charAt(--var) + " ");
}
else {
System.out.print(str.charAt(0) + " ");
}
}
public static void main(String args[]) {
doStuff("abcd");
doStuff("efg");
doStuff("hi");
}
}
A) Compilation fails.
B) An exception is thrown at runtime.
C) d e h
D) d f i
E) c f i
F) c e h
-----------------------------------------------------------------------
The code below is executed by "java -Dmyprop=myprop Test". Which two, placed instead of "//some code goes here", will produce the output "myprop"? (Choose two)
public class Test {
public static void main(String args[]) {
String prop = //some code goes here//
System.out.print(prop);
}
}
A) System.getEnv("myprop");
B) System.load("myprop");
C) System.property("myprop");
D) System.getProperty("myprop");
E) System.get("myprop");
F) System.getProperties().getProperty("myprop");
---------------------------------------------------------------------------
Given the code. Select correct calls of methods. (Select all that apply)
import java.util.*;
class Empty {
}
class Extended extends Empty {
}
public class TryMe {
public static void doStuff1(List<Empty> list) {
// some code
}
public static void doStuff2(List list) {
// some code
}
public static void doStuff3(List<? extends Empty> list) {
// some code
}
public static void main(String args[]) {
List<Empty> list1 = new LinkedList<Empty>();
List<Extended> list2 = new LinkedList<Extended>();
// more code here
}
}
A) doStuff1(list1);
B) doStuff2(list2);
C) doStuff2(list1);
D) doStuff3(list1);
E) doStuff3(list2);
F) doStuff1(list2);
---------------------------------------------------------------------------------
Given the code. What is the result after the class TryMe execution?
class A {
public void doA() {
B b = new B();
b.dobB();
System.out.print("doA");
}
}
class B {
public void dobB() {
C c = new C();
c.doC();
System.out.print("doB");
}
}
class C {
public void doC() {
if (true)
throw new NullPointerException();
System.out.print("doC");
}
}
public class TryMe {
public static void main(String args[]) {
try {
A a = new A();
a.doA();
} catch (Exception ex) {
System.out.print("error");
}
}
}
A) "doCdoBdoA" is printed
B) "doAdoBdoC" is printed
C) "doBdoAerror" is printed
D) "error" is printed
E) nothing is printed
---------------------------------------------------------------------
Given:
System.out.printf("Pi = %f and E = %b", Math.PI, Math.E).
Place values where they would appear in the output
Pi = 3.141593 and E = 2.718282
3 2 true false
--------------------------------------------------------------------
Given the code. What is the result?
public class SomeClass {
private int value = 1;
public int getValue() {
return value;
}
public void changeVal(int value) {
value = value;
}
public static void main(String args[]) {
int a = 2;
SomeClass c = new SomeClass();
c.changeVal(a);
System.out.print(c.getValue());
}
}
A) "1" is printed // correct answer
B) "2" is printed
C) Compilation fails
D) An exception is thrown at runtime
-------------------------------------------------------------------
Which of the following lines will print false?
1.public class MyClass
2.{
3. static String s1 = "I am unique!";
4. public static void main(String[] args)
5. {
6. String s2 = "I am unique!";
7. String s3 = new String(s1);
8. System.out.println(s1 == s2);
9. System.out.println(s1.equals(s2));
10. System.out.println(s3 == s1);
11. System.out.println(s3.equals(s1));
12. }
13.}
a. Line 8
b. Line 9
c. Line 10// correct answer
d. Line 11
e. None of these
-------------------------------------------------------------------
What is the result of compiling and running the following code?
public class IntegerTest
{
public static void main(String[] argv)
{
Integer i1 = new Integer("1");
Integer i2 = new Integer("2");
Integer i3 = Integer.valueOf("3");
int i4 = i1 + i2 + i3;
System.out.println(i4);
}
}
a. Compiler error: Integer class has no constructors which take a String argument
b. Compiler error: Incorrect argument passed to the valueOf method
c. Compiler error: Integer objects cannot work with + operator
d. Prints 6 // CORRECT ANSWER
e. Prints 123
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