Oracle Advacned Java Advanced Certification Questions and Answers (Dumps and Practice Questions)
Question : You have been given below code, what is the expected behavior?
package com.hadoopexam;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
class Welcome {
public enum Courses {
HADOOP, SPARK, JAVA
}
String name;
Courses course;
public Welcome(String na, Courses cs) {
name = na;
course = cs;
}
public String getName() {
return name;
}
public Courses getCourses() {
return course;
}
public static void main(String[] args) {
List
new Welcome ("Jayesh", Welcome.Courses.HADOOP),
new Welcome ("Imtiaz", Welcome.Courses.HADOOP),
new Welcome ("Gautam", Welcome.Courses.SPARK));
Map
.collect(Collectors.groupingBy (Welcome ::getCourses,Collectors.mapping(Welcome::getName, Collectors.toList())));
System.out.println(userMap);
}
}
1. Compilation error
2. It will print {SPARK=[Gautam], HADOOP=[Jayesh, Imtiaz]}
3. It will print {Gautam =[ SPARK], Jayesh=[ HADOOP, HADOOP]}
4. It will print {Gautam =[ SPARK], Jayesh=[ HADOOP], Imtiaz=[HADOOP]}
Correct Answer : 2
Explanation: The arrow operator ("->") for defining lambda functions, the double colon operator ("::") used for method references.
Method references use the "::" operator. Here is a simplified expression using method references:
strings.forEach(System.out::println);
Method references route the given parameters. In this case, System.out::println is equivalent to using
the lambda expression string -> System.out.println(string).
How about simplifying the following statement to use method references?
strings.forEach(string -> System.out.println(string.toUpperCase()));
The lambda expression in this code calls toUpperCase() method on the given String object. Since
method references just route the parameters, so you cannot use them directly for simplifying this lambda
expression. An alternative is to put this code inside a method and use the reference of that method.
java.util.Collection.stream()
Returns a sequential Stream with this collection as its source.
This method should be overridden when the spliterator() method cannot return a spliterator that is IMMUTABLE, CONCURRENT, or late-binding. (See spliterator() for details.)
The groupingBy() . Will do the grouping based on key, value. Key is the course name and values is the all the users who had subscribed to the course.
Question : You have been given below code, what will be the behavior of the code ?
package com.hadoopexam;
public class Welcome {
CompanyName companyName;
enum CompanyName {
HADOOPEXAM, QUICKTECHIE, TRAINING4EXAM
};
public Welcome(CompanyName pType) {
companyName = pType;
}
public static void main(String[] args) {
CompanyName cName = new CompanyName();
Welcome wel = new Welcome(CompanyName.HADOOPEXAM);
}
}
1. It will compile and run perfectly
2. It will compile but will run with Error
3. It will run perfectly and print the HADOOPEXAM
4. It will give compile time error.
Correct Answer : 4
Explanation: It can not compile, because you are trying to instantiate enum CompanyName using new operator. Which you can not do.
Question : You have been given below code, what behavior you are expecting.
package com.hadoopexam;
public enum Welcome {
private int totalProducts; // n1
HadoopExam(30), QuickTechie(5), Training4Exam(50); // n2
private Welcome(int totalProducts) {
this.totalProducts = totalProducts;
}
public int getTotalProducts() {
return totalProducts;
}
}
1. It will compile successfully
2. It will compile, but can not run successfully.
3. This is enum definition is not correct, it will through compile time errors.'
4. It will compile and run successfully.
Correct Answer : 3
Explanation: When you define an enum class then , enum elements should be in first, before appearing any other enum. Hence, in given code n2 line should be above line n1.
Related Questions
Question : You have been given below code. What is the expected behavior ?
package com.hadoopexam;
class Welcome {
public static void main(String[] args) {
"HadoopExam.com".chars().distinct().peek(ch -> System.out.printf("%c ", ch)).sorted();
}
}
1. Code will through a compile time error.
2. Code will run perfectly and print "H a d o p E x m . c"
3. Access Mostly Uused Products by 50000+ Subscribers
4. Code will run perfectly and print ". a c d m o p x E H "
Question : You have been given below code, what is the expected behavior?
package com.hadoopexam;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.stream.Stream;
public class Welcome {
public static void main(String[] args) throws IOException {
Stream
userHomes.forEach (fName ->
{//line n1
try
{
Path aPath = fName.toAbsolutePath();//line n2
System.out.println(fName + ":" + Files.readAttributes(aPath, BasicFileAttributes.class).creationTime());
} catch (IOException ex)
{
ex.printStackTrace();
}
});
}
}
1. All files and directories under thehomedirectory are listed along with their attributes.
2. A compilation error occurs atline n1.
4. A compilation error occurs atline n2.
Question : You have been given below code, what is the behavior expected?
package com.hadoopexam;
import java.util.Set;
import java.util.TreeSet;
public class Welcome {
int userId;
String userName;
public Welcome(int userId, String userName) {
this.userId = userId;
this.userName = userName;
}
public String toString() {
return userId + ":" + userName;
}
public static void main(String[] args) {
Set
users.add(new Welcome (101, "Amit"));
users.add(new Welcome (102, "Anurag"));
System.out.println(users);
}
}
1. 101 : Amit , 102:Anurag
2. 102 : Anurag , 102: Amit
4. It will give compile time error.
5. It will give runtime error "java.lang.ClassCastException: com.hadoopexam.Welcome cannot be cast to java.lang.Comparable"
Question : You have been given below code, what is expected behavior?
package com.hadoopexam;
import java.io.FileInputStream;
import java.io.InputStreamReader;
public class Welcome {
public static void main(String[] args) {
int i;
char c;
try (FileInputStream fileInputStream = new FileInputStream("resources\\Message.properties");
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);) {
while (inputStreamReader.ready()) { // line n1
inputStreamReader.skip(2);
i = inputStreamReader.read();
c = (char) i;
System.out.print(c);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
1. tHoEmo?
2. t:HoEmo?
3. Access Mostly Uused Products by 50000+ Subscribers
4. A compilation error occurs at line n1.
Question : You have been given below code, what is the expected output?
package com.hadoopexam;
public class Welcome
private T t;
public T get() {
return t;
}
public void set(T t) {
this.t = t;
}
public static void main(String args[]) {
Welcome
Welcome userId = new Welcome();// line n1
siteName.set("HadoopExam.com");
userId.set(101);// line n2
System.out.print(siteName.get() + ":" + userId.get());
}
}
1. HadoopExam.com:101
2. java.lang.string@
Welcome userId = new Welcome();
4. A compilation error occurs. To rectify it, replace line n2with:
userId.set (Integer(101));
Question : You have been given below class and its member variables ,
package com.hadoopexam;
public class Welcome
String name;
void setName(String name) {
this.name = name;
}
String getName() {
return name;
}
}
Which action encapsulates the Welcome class?
1. Make the Vehicle class public.
2. Make the name variable public.
4. Make the name variable private.
5. Make the setName method private.