Oracle 1z1-829 Dumps - 100% Cover Real Exam Questions (Updated 50 Questions)
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NEW QUESTION # 21
Given the code fragment:
Which code line n1, obtains the java.io.Console object?
- A.
- B.
- C.
- D.
- E.
Answer: D
Explanation:
The code fragment is trying to obtain the java.io.Console object, which is a class that provides methods to access the character-based console device, if any, associated with the current Java virtual machine. The correct way to obtain the Console object is to call the static method Console console() in the java.lang.System class. This method returns the unique Console object associated with the current Java virtual machine, if any. Therefore, option A is correct, as it calls System.console() and assigns it to a Console variable. Reference:
https://docs.oracle.com/javase/17/docs/api/java.base/java/io/Console.html
https://docs.oracle.com/javase/17/docs/api/java.base/java/lang/System.html#console()
https://education.oracle.com/products/trackp_OCPJSE17
https://mylearn.oracle.com/ou/learning-path/java-se-17-developer/99487
NEW QUESTION # 22
Assume you have an automatic module from the module path display-ascii-0.2. jar. Which name is given to the automatic module based on the given JAR file?
- A. Display-ascii-0.2
- B. Display.ascii
- C. Display-ascii
- D. Display-ascii-0
Answer: C
Explanation:
Explanation
An automatic module name is derived from the name of the JAR file when it does not contain a module-info.class file. If the JAR file has an "Automatic-Module-Name" attribute in its main manifest, then its value is the module name. Otherwise, the module name is derived from the JAR file's name by removing any version numbers and converting it to lower case. Therefore, for a JAR named display-ascii-0.2.jar, the automatic module name would be display-ascii, following these rules.
NEW QUESTION # 23
Given:
Which two modifications enable the code to print Open Close?
- A.
- B.
- C.
- D.
- E.
Answer: A,C
Explanation:
The code given is a try-with-resources statement that declares a resource of type AutoCloseable. The resource is an anonymous class that implements the AutoCloseable interface and overrides the close() method. The code also has a print() method that prints the value of the variable s. The code is supposed to print "Open Close", but it does not compile because of two errors.
The first error is at line n1, where the anonymous class is missing a semicolon at the end of its declaration. This causes a syntax error and prevents the code from compiling. To fix this error, option B adds a semicolon after the closing curly brace of the anonymous class.
The second error is at line n2, where the print() method is called without an object reference. This causes a compilation error because the print() method is not static and cannot be invoked without an object. To fix this error, option E adds an object reference to the print() method by using the variable t.
Therefore, options B and E are correct and enable the code to print "Open Close".
NEW QUESTION # 24
Given:
What is the result?
- A. Mb
- B. Mb
- C. MA
- D. mA
- E. Mb
MC
Answer: D
Explanation:
The code snippet is an example of Java SE 17 code. The code is checking if the object is an instance of class C and if it is, it will print "mC". If it is not an instance of class C, it will print "mA". In this case, the object is not an instance of class C, so the output will be "mA". Reference: Pattern Matching for instanceof - Oracle Help Center
NEW QUESTION # 25
Given the code fragment:
What is the result?
- A. Logged out at: 2021-01-12T21:58:00z
- B. A compilation error occurs at Line n1.
- C. Can't logout
- D. Logged out at: 2021-0112T21:58:19.880z
Answer: A
Explanation:
Explanation
The code fragment is using the Java SE 17 API to get the current time and then truncating it to minutes. The result will be the current time truncated to minutes, which is why option B is correct. References:
https://education.oracle.com/products/trackp_OCPJSE17
https://mylearn.oracle.com/ou/learning-path/java-se-17-developer/99487
https://docs.oracle.com/javase/17/docs/api/java.base/java/time/Instant.html#truncatedTo(java.time.tempora
NEW QUESTION # 26
Given:
Which two method invocation execute?
- A. IFace.m2();
- B. iFace mucloassObj = new Myc ();
myClassObj.m4(); - C. IFace myclassobj = new Myc ();
myclassObj.m3 (); - D. IFace .,4():
- E. Ifnce.m3 ();
- F. new MyC() .m2 ();
Answer: D,F
Explanation:
The code given is an interface and a class that implements the interface. The interface has three methods, m1(), m2(), and m3(). The class has one method, m1(). The only two method invocations that will execute are D and E. D is a call to the m2() method in the class, and E is a call to the m3() method in the interface. Reference: https://education.oracle.com/products/trackp_OCPJSE17, 3, 4, 5
NEW QUESTION # 27
Given:
What is the result?
- A. 0 Snowy
- B. 1 Snowy
- C. 0 CLOUDY
- D. Compilation fails
- E. 1 RAINY
Answer: A
Explanation:
The code is defining an enum class called Forecast with three values: SUNNY, CLOUDY, and RAINY. The toString() method is overridden to always return "SNOWY". In the main method, the ordinal value of SUNNY is printed, which is 0, followed by the value of CLOUDY converted to uppercase, which is "CLOUDY". However, since the toString() method of Forecast returns "SNOWY" regardless of the actual value, the output will be "0 SNOWY". Reference: Enum (Java SE 17 & JDK 17), Enum.EnumDesc (Java SE 17 & JDK 17)
NEW QUESTION # 28
Given:
What is the result?
- A. flipsruns
- B. runsruns
- C. Compilation fails
- D. flipsflips
- E. runsflips
Answer: C
Explanation:
The code fragment will fail to compile because the play method in the Dog class is declared as private, which means that it cannot be accessed from outside the class. The main method is trying to call the play method on a Dog object, which is not allowed. Therefore, the code fragment will produce a compilation error.
NEW QUESTION # 29
Given the code fragment:
What is the result?
- A. Logged out at: 2021-01-12T21:58:00z
- B. A compilation error occurs at Line n1.
- C. Can't logout
- D. Logged out at: 2021-0112T21:58:19.880z
Answer: A
Explanation:
The code fragment is using the Java SE 17 API to get the current time and then truncating it to minutes. The result will be the current time truncated to minutes, which is why option B is correct. Reference:
https://education.oracle.com/products/trackp_OCPJSE17
https://mylearn.oracle.com/ou/learning-path/java-se-17-developer/99487
https://docs.oracle.com/javase/17/docs/api/java.base/java/time/Instant.html#truncatedTo(java.time.temporal.TemporalUnit)
NEW QUESTION # 30
Given the content of the in. tart file:
23456789
and the code fragment:
What is the content of the out .txt file?
- A. 012345678901234
- B. 01234567
- C. 012345678
- D. 0123456789234567
- E. 0123456789
- F. 01234567801234
Answer: E
Explanation:
Explanation
The answer is D because the code fragment reads the content of the in.txt file and writes it to the out.txt file.
The content of the in.txt file is "23456789". The code fragment uses a char array buffer of size 8 to read the content of the in.txt file. The while loop reads the content of the in.txt file and writes it to the out.txt file until the end of the file is reached. Therefore, the content of the out.txt file will be "0123456789".
NEW QUESTION # 31
Given:
What is the result?
- A. Software Game Chess 2
- B. Software Game Software Game Chese 2
- C. Software Game Software Game chess 0
- D. Software game write error
- E. Software Game Chess 0
- F. Software Game read error
Answer: B
Explanation:
Explanation
The answer is B because the code uses the writeObject and readObject methods of the ObjectOutputStream and ObjectInputStream classes to serialize and deserialize the Game object. These methods use the default serialization mechanism, which writes and reads the state of the object's fields, including the inherited ones. Therefore, the title field of the Software class is also serialized and deserialized along with the players field of the Game class. The toString method of the Game class calls the toString method of the Software class using super.toString(), which returns the value of the title field.
Hence, when the deserialized object is printed, it shows "Software Game Software Game Chess 2".
References:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Serialization and Deserialization in Java with Example
NEW QUESTION # 32
Given:
What is the result?
- A. Compilation fails.
- B. (3:bicycle, 0:car, 0motercycle, 5:truck)
- C. Bicycle-1, car=3, motorcycle=1, truck=2)
- D. Bicycle =7, car=7, motorcycle=7, truck=7)
- E. (Bicycle, car, motorcycle, truck)
Answer: A
Explanation:
The answer is E because the code fragment contains several syntax errors that prevent it from compiling. Some of the errors are:
The enum declaration is missing a semicolon after the list of constants.
The enum constants are not capitalized, which violates the Java naming convention for enums.
The switch expression is missing parentheses around the variable name.
The case labels are missing colons after the enum constants.
The default label is missing a break statement, which causes a fall-through to the next case.
The println statement is missing a closing parenthesis and a semicolon.
A possible corrected version of the code fragment is:
enum Vehicle { BICYCLE, CAR, MOTORCYCLE, TRUCK; } public class Test { public static void main(String[] args) { Vehicle v = Vehicle.BICYCLE; switch (v) { case BICYCLE: System.out.print("1"); break; case CAR: System.out.print("3"); break; case MOTORCYCLE: System.out.print("1"); break; case TRUCK: System.out.print("2"); break; default: System.out.print("0"); break; } System.out.println(); } } This would print 1 as the output. Reference:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Enum Types
The switch Statement
NEW QUESTION # 33
Given the code fragment:
What is the result?
- A. false 1
false 2 - B. true 1
false 2 - C. falase 0
true 1 - D. false 1
ture 2
Answer: B
Explanation:
Explanation
The code fragment is comparing the values of a, b, and c using the < and > operators. The first comparison, d, is checking if a is less than b and greater than c. Since a is equal to 2, b is equal to -2, and c is equal to -4, this comparison will evaluate to true. The second comparison, e, is checking if a is greater than b and a is greater than c. Since a is equal to 2, b is equal to -2, and c is equal to -4, this comparison will evaluate to false.
Therefore, the result will be true 1 false 2. References: Operators (The Java™ Tutorials > Learning the Java Language - Oracle
NEW QUESTION # 34
Given the code fragment:
What is the result?
- A. PT5000PT60MP6D
- B. PT5SPTIMP6D
- C. 5000$60M6D
- D. $SIM6D
Answer: A
Explanation:
The code fragment is creating a Duration object with a value of 5000 milliseconds, then printing it. Then, it is creating another Duration object with a value of 60 seconds, then printing it. Finally, it is creating a Period object with a value of 6 days, then printing it. The output will be "PT5000PT60MP6D". Reference: https://docs.oracle.com/javase/8/docs/api/java/time/Duration.html, https://docs.oracle.com/javase/8/docs/api/java/time/Period.html
NEW QUESTION # 35
Given the code fragment:
Which code fragment returns different values?
- A. int sum = listOfNumbers. Stream () reduce (5, (a, b) -> a + b) ;
- B. int sum = listOfNumbers. parallelStream () reduce ({m, n) -> m +n) orElse (5) +5;
- C. int sum = listOfNumbers. Stream () reduce (0, Integer:: sum) + 5
- D. int sum = listOfNumbers. parallelStream () reduce (5, Integer:: sum) ;
- E. int sum = listOfNumbers. Stream () reduce ( Integer:: sum) ; +5;
Answer: E
Explanation:
The answer is C because the code fragment uses a different syntax and logic for the reduce operation than the other options. The reduce method in option C takes a single parameter, which is a BinaryOperator that combines two elements of the stream into one. The method returns an Optional, which may or may not contain a value depending on whether the stream is empty or not. The code fragment then adds 5 to the result of the reduce method, regardless of whether it is present or not. This may cause an exception if the Optional is empty, or produce a different value than the other options if the Optional is not empty.
The other options use a different syntax and logic for the reduce operation. They all take two parameters, which are an identity value and a BinaryOperator that combines an element of the stream with an accumulator. The method returns the final accumulator value, which is equal to the identity value if the stream is empty, or the result of applying the BinaryOperator to all elements of the stream otherwise. The code fragments then add 5 to the result of the reduce method, which will always produce a valid value.
For example, suppose listOfNumbers contains [1, 2, 3]. Then, option A will perform the following steps:
Initialize accumulator to identity value 5
Apply BinaryOperator Integer::sum to accumulator and first element: 5 + 1 = 6 Update accumulator to 6 Apply BinaryOperator Integer::sum to accumulator and second element: 6 + 2 = 8 Update accumulator to 8 Apply BinaryOperator Integer::sum to accumulator and third element: 8 + 3 = 11 Update accumulator to 11 Return final accumulator value 11 Add 5 to final accumulator value: 11 + 5 = 16 Option B will perform the same steps as option A, except using a lambda expression instead of a method reference for the BinaryOperator. Option D will perform the same steps as option A, except using parallelStream instead of stream, which may change the order of applying the BinaryOperator but not the final result. Option E will perform the same steps as option A, except using identity value 0 instead of 5.
Option C, however, will perform the following steps:
Apply BinaryOperator Integer::sum to first and second element: 1 + 2 = 3 Apply BinaryOperator Integer::sum to previous result and third element: 3 + 3 = 6 Return Optional containing final result value 6 Add 5 to Optional value: Optional.of(6) + 5 = Optional.of(11) As you can see, option C produces a different value than the other options, and also uses a different syntax and logic for the reduce operation. Reference:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Guide to Stream.reduce()
NEW QUESTION # 36
Given the code fragments:
Which is true?
- A. The program prints an exception
- B. The program prints t1 : 1: t2 : 1: t1 : t2 : 2 : in random order.
- C. The program prints t1 : 1 : t2: 1 : t1 : 2 : t2: 2:
- D. The program prints t1 : 1: t2 : 1: t1 : 1 : t2 : 1 : indefinitely
Answer: C
Explanation:
The code creates two threads, t1 and t2, and starts them. The threads will print their names and the value of the Atomic Integer object, x, which is initially set to 1. The threads will then increment the value of x and print their names and the new value of x. Since the threads are started at the same time, the output will be in random order. However, the final output will always be t1 : 1 : t2: 1 : t1 : 2 : t2: 2: Reference: AtomicInteger (Java SE 17 & JDK 17) - Oracle
NEW QUESTION # 37
Given the code fragment:
What is the result?
- A. False true true optional (Newyear)
- B. 0110
- C. 010 optional (Newyear)
- D. True true false NewYear
Answer: A
Explanation:
The code fragment is using the stream methods allMatch, anyMatch, noneMatch, and findFirst on a list of strings called specialDays. These methods are used to perform matching operations on the elements of a stream, such as checking if all, any, or none of the elements satisfy a given predicate, or finding the first element that matches a predicate1. The predicate in this case is that the string equals "Labour" or "Halloween". The output will be:
False: because not all of the elements in specialDays are equal to "Labour" or "Halloween".
true: because at least one of the elements in specialDays is equal to "Labour" or "Halloween".
true: because none of the elements in specialDays are equal to both "Labour" and "Halloween".
Optional[NewYear]: because the first element in specialDays that matches the predicate is "NewYear", and the findFirst method returns an Optional object that may or may not contain a non-null value2.
NEW QUESTION # 38
Given the code fragment:
What is the result?
- A. 1
1
1 - B. 1
2
-4 - C. 0
B 2
C -2 - D. 2
2
0
Answer: D
Explanation:
The code fragment uses the Collections.binarySearch method to search for the string "e3" in the list. The first search returns the index of the element, which is 2. The second search returns the index of the element, which is 0. The third search returns the index of the element, which is -4. The final result is 2. Reference: Collections (Java SE 17 & JDK 17) - Oracle
NEW QUESTION # 39
Given:
What is the result?
- A. D D D
- B. B A D
- C. B A C
- D. D A D
Answer: B
Explanation:
Explanation
The answer is C because the code demonstrates the concept of method overloading and type conversion in Java. Method overloading allows different methods to have the same name but different parameters. Type conversion allows values of one data type to be assigned to another data type, either automatically or explicitly. In the code, the class Test has four methods named sum, each with different parameter types: int, float, and double. The main method creates an instance of Test and calls the sum method with different arguments. The compiler will choose the most specific method that matches the arguments, based on the following rules:
If there is an exact match between the argument types and the parameter types, that method is chosen.
If there is no exact match, but there is a method with compatible parameter types, that method is chosen.
Compatible types are those that can be converted from one to another automatically, such as int to long or float to double.
If there is more than one method with compatible parameter types, the most specific method is chosen.
The most specific method is the one whose parameter types are closest to the argument types in terms of size or precision.
In the code, the following method calls are made:
test.sum(10, 10.5) -> This matches the sum(int a, float b) method exactly, so it is chosen.
The result is 20.5, which is converted to int and printed as 20 (B).
test.sum(10) -> This does not match any method exactly, but it matches the sum(double a) method with compatible types, as int can be converted to double automatically. The result is 10.0, which is printed as 10
(A). test.sum(10.5, 10) -> This does not match any method exactly, but it matches two methods with compatible types: sum(float a, float b) and sum(double a, double b). The latter is more specific, as double is closer to the argument types than float. The result is 20.5, which is printed as 20 (D).
Therefore, the output is B A D. References
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Method Overloading in Java
Type conversion in Java with Examples
Java Method Overloading with automatic type conversions
NEW QUESTION # 40
Given the code fragment:
What is the result?
- A. false 1
false 2 - B. false 1
ture 2 - C. true 1
false 2 - D. falase 0
true 1
Answer: D
Explanation:
The code fragment is comparing the values of a, b, and c using the < and > operators. The first comparison, d, is checking if a is less than b and greater than c. Since a is equal to 2, b is equal to -2, and c is equal to -4, this comparison will evaluate to true. The second comparison, e, is checking if a is greater than b and a is greater than c. Since a is equal to 2, b is equal to -2, and c is equal to -4, this comparison will evaluate to false. Therefore, the result will be true 1 false 2. Reference: Operators (The Java™ Tutorials > Learning the Java Language - Oracle
NEW QUESTION # 41
Which two code fragments compile?
- A.
- B.
- C.
- D.
- E.
Answer: D,E
Explanation:
Explanation
The two code fragments that compile are B and E. These are the only ones that use the correct syntax for declaring and initializing a var variable. The var keyword is a reserved type name that allows the compiler to infer the type of the variable based on the initializer expression. However, the var variable must have an initializer, and the initializer must not be null or a lambda expression. Therefore, option A is invalid because it does not have an initializer, option C is invalid because it has a null initializer, and option D is invalid because it has a lambda expression as an initializer. Option B is valid because it has a String initializer, and option E is valid because it has an int initializer.
https://docs.oracle.com/en/java/javase/17/language/local-variable-type-inference.html
NEW QUESTION # 42
......
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