Oracle 1Z0-804 Dumps Questions 2021

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Given the code fragment: SimpleDataFormat sdf;
Which code fragment displays the three-character month abbreviation?

  • A. SimpleDateFormat sdf = new SimpleDateFormat ("mm", Locale.UK); System.out.println ("Result:" +sdf.format(new Date()));
  • B. SimpleDateFormat sdf = new SimpleDateFormat ("MM", Locale.UK); System.out.println ("Result:" +sdf.format(new Date()));
  • C. SimpleDateFormat sdf = new SimpleDateFormat ("MMM", Locale.UK); System.out.println ("Result:" +sdf.format(new Date()));
  • D. SimpleDateFormat sdf = new SimpleDateFormat ("MMMM", Locale.UK); System.out.println ("Result:" +sdf.format(new Date()));

Answer: C

View the exhibit:
1Z0-804 dumps exhibit
Given the code fragment:
1Z0-804 dumps exhibit
What is the result?

  • A. Compilation fails
  • B. 6
  • C. 4
  • D. 1
  • E. 3
  • F. Not possible to answer due to missing exhibit.

Answer: C

Explanation: C: 4 Falls geändert zu: return FileVisitResult.CONTINUEsonst A: weil CONTINUE als Konstante unbekannt
Note: TheFileSystems.getDefault() returns the default FileSystem. The default file system creates objects thatprovide access to the file systems accessible to the Java virtual machine. The working directory of the filesystem is the current user directory, named by the system property user.dir.

Which four are true about enums?

  • A. An enum is typesafe.
  • B. An enum cannot have public methods or fields.
  • C. An enum can declare a private constructor.
  • D. All enums implicitly implement Comparable.
  • E. An enum can subclass another enum.
  • F. An enum can implement an interface.

Answer: ACDF

Explanation: C: The constructor for an enum type must be package-private or private access. Reference: Java Tutorials,Enum Types

1Z0-804 dumps exhibit
What is the result?

  • A. Compilation succeeds.
  • B. Compilation fails due to an error on line 1.
  • C. Compilation fails due to an error on line 2.
  • D. Compilation fails due to an error on line 3.
  • E. Compilation fails due to an error on line 4.
  • F. Compilation fails due to an error on line 8.

Answer: A

Given the code fragment:
1Z0-804 dumps exhibit
What is the result of the employees table has no records before the code executed?

  • A. 1 Sam
  • B. 4 Jack
  • C. 3 John4 Jack
  • D. 1 Sam3 John4 Jack

Answer: C

Explanation: AutoCommit is set to false. The two following statements will be within the same transaction.
stmt.executeUpdate("insert into employees values(1,'Sam')"); stmt.executeUpdate("insert into employees values(2,'Jane')");
These two statements are rolled-back through (the savepoint is ignored! the savepoint must be specified (e.g.
conn.rollback(save1); ) in the rollback if you want to rollback to the savepoint): conn.rollback() ;
The next two insert statements are executed fine. Their result will be in the output.

Given this code fragment:
1Z0-804 dumps exhibit
Assume that the SQL query returns records. What is the result?

  • A. Compilation fails due to error at line 17
  • B. The program prints Error
  • C. The program prints each record
  • D. Compilation fails at line 14

Answer: C

Which statement creates a low overhead, low-contention random number generator that is isolated to thread togenerate a random number between 1 and 100?

  • A. int i = ThreadLocalRandom.current().nextInt(1, 101);
  • B. int i = ThreadSafeRandom.current().nextInt(1, 101);
  • C. int i = (int) Math.random()*100+1;
  • D. int i = (int) Math.random(1, 101);
  • E. int i = new random().nextInt(100)+1;

Answer: A

Explanation: public class ThreadLocalRandom extends Random
A random number generator isolated to the current thread. Like the global Random generator used by the Mathclass, a ThreadLocalRandom is initialized with an internally generated seed that may not otherwise bemodified. When applicable, use of ThreadLocalRandom rather than shared Random objects in concurrentprograms will typically encounter much less overhead and contention. Use of ThreadLocalRandom isparticularly appropriate when multiple tasks (for example, each a ForkJoinTask) use random numbers inparallel in thread pools. Usages of this class should typically be of the form: ThreadLocalRandom.current().nextX(...) (where X is Int, Long, etc). When all usages are of this form, it is never possible to accidently share a ThreadLocalRandom across multiple threads.
This class also provides additional commonly used bounded random generation methods. Reference:Class ThreadLocalRandom

Which code fragment demonstrates the proper way to handle JDBC resources?

  • A. try {ResultSet rs = stmt.executeQuery (query); statement stmt = con.createStatement(); while ( (/* . . . */)} catch (SQLException e) {}
  • B. try {Statement stmt = con.createStatement(); ResultSet rs = stmt.executeQuery (query); while ( (/* . . . */)} catch (SQLException e) {}
  • C. try {Statement stmt = con.createStatement();ResultSet rs = stmt.executeQuery (query); while ( (/* . . . */)} finally { rs.close();stmt.close();}
  • D. try {ResultSet rs = stmt.executeQuery (query); Statement stmt = con.createStatement(); while ( (/* . . . */)} finally { rs.close();stmt.close();}

Answer: C

Which two forms of abstraction can a programmer use in Java?

  • A. enums
  • B. interfaces
  • C. primitives
  • D. abstract classes
  • E. concrete classes
  • F. primitive wrappers

Answer: BD

Explanation: When To Use Interfaces
An interface allows somebody to start from scratch to implement your interface or implement your interface insome other code whose original or primary purpose was quite different from your interface. To them, yourinterface is only incidental, something that have to add on to thetheir code to be able to use your package. Thedisadvantage is every method in the interface must be public. You might not want to expose everything.
*When To Use Abstract classes
An abstract class, in contrast, provides more structure. It usually defines some default implementations andprovides some tools useful for a full implementation. The catch is, code using it must use your class as thebase. That may be highly inconvenient if the other programmers wanting to use your package have alreadydeveloped their own class hierarchy independently. In Java, a class can inherit from only one base class.*When to Use Both
You can offer the best of both worlds, an interface and an abstract class. Implementors can ignore yourabstract class if they choose. The only drawback of doing that is calling methods via their interface name isslightly slower than calling them via their abstract class name.

Given the code fragment:
1Z0-804 dumps exhibit
Which two try statements, when inserted at line ***, enable the code to successfully move the file info.txt to thedestination directory, even if a file by the same name already exists in the destination directory?

  • A. try (FileChannel in = new FileInputStream (source). getChannel(); FileChannel out = new FileOutputStream(dest).getChannel()) { in.transferTo(0, in.size(), out);
  • B. try ( Files.copy(Paths.get(source),Paths.get(dest)); Files.delete (Paths.get(source));
  • C. try ( Files.copy(Paths.get(source), Paths.get(dest),StandardCopyOption.REPLACE_EXISTING); Files.delete (Paths.get(source));
  • D. try (Files.move(Paths.get(source),Paths.get(dest));
  • E. try(BufferedReader br = Files.newBufferedReader(Paths.get(source), Charset.forName("UTF- 8"));BufferedWriter bw = Files.newBufferedWriter(Paths.get(dest), Charset.forName("UTF-8")); String record ="";while ((record = br.readLine()) ! = null) { bw.write(record);bw.newLine();}Files.delete(Paths.get(source));

Answer: CE

Explanation: A: copies only, don’t move operation
B,C,D (no try-with-resource !) syntax change to: try { … B: throws FileAlreadyExistsException
C: correct if syntax change to : StandardCopyOption.REPLACE_EXISTING (before REPLACE_Existing)
D: throws FileAlreadyExistsException
E: works properly if the sourcefile has the correct format, utf-8 here (else throws MalformedInputException)
AND syntax is corrected to:
try ( BufferedReader br = Files.newBufferedReader(Paths.get(source), Charset.forName(“UTF-8));
BufferedWriter bw = Files.newBufferedWriter(Paths.get(dest), Charset.forName(“UTF-8));
String record = “”;

1Z0-804 dumps exhibit
What is the result of invoking Car's scop method?

  • A. Both vehicles and Motorized's stop methods are invoked.
  • B. Vehicles stop method is invoked.
  • C. Motorized's stop method is invoked-
  • D. The implementation of the Car's stop determines the behavior.
  • E. Compilation fails.

Answer: D

Explanation: The Car class is implementing the methods. Methods are not implemented in interfaces.

1Z0-804 dumps exhibit
Which of the four are valid modifications to synchronize access to the valid list between threads t1 and t2?

  • A. Replace line 1 with:Synchronized (t2) (t1.start();) synchronized(t1) (t2.start(); )korrekte Schreibweise: synchronized (t2) {t1.start();} synchronized(t1) { t2.start();}
  • B. Replace Line 2 with:static CopyWriteArrayList<Integer> list = new CopyWriteArrayList<>(); korrekte Schreibweise: static CopyOnWriteArrayList<Integer> list = new CopyOnWriteArrayList<>();
  • C. Replace line 3 with:synchronized public static void addItem () {korrekte Schreibweise: synchronized public static void addItem () {
  • D. Replace line 4 with: synchronized (list) (list.add(1);)korrekte Schreibweise: synchronized (list) { (list.add(1); }
  • E. Replace line 5 with: Synchronized public void run () {korrekte Schreibweise: synchronized public void run () {
  • F. replace line 6 with:Synchronized (this) {for (in i = 0, i<5000, i++) WorkPool.addItem(); }korrekte Schreibweise: synchronized (this) {for (int i = 0; i<500; i++) WorkPool.addItem(); }
  • G. Replace line 6 with:synchronized (bar) {for (int i= 0; i<5000; i++) WorkPool.addItem(); }korrekte Schreibweise: synchronized (bar) {for (int i= 0; i<500; i++) WorkPool.addItem(); }

Answer: BCD

Explanation: Away to create synchronized code is with synchronized statements.
Unlike synchronized methods, synchronized statements must specify the object that provides theintrinsic lock:
For example:
public void addName(String name) { synchronized(this) {
lastName = name; nameCount++;
In this example, the addName method needs to synchronize changes to lastName and nameCount, but alsoneeds to avoid synchronizing invocations of other objects' methods. Without synchronized statements, therewould have to be a separate, unsynchronized method for the sole purpose of invoking nameList.add.
Reference: The Java Tutorial,Intrinsic Locks and Synchronization

Given the code fragment:
1Z0-804 dumps exhibit
Which three are true?

  • A. On line 3, the current thread stops and waits until the t1 thread finishes.
  • B. On line 3, the t1 thread stops and waits until the current thread finishes.
  • C. On line 4, the t1 thread is dead.
  • D. On line 4, the t1 thread is waiting to run.
  • E. This code cannot throw a checked exception.
  • F. This code may throw a checked exception.

Answer: ACF

Explanation: Thejoin()methods waits for this thread to die.

Given the code fragment:
1Z0-804 dumps exhibit
What is the result when the result.txt file already exists in c:student?

  • A. The program replaces the file contents and the file's attributes and prints Equal.
  • B. The program replaces the file contents as well as the file attributes and prints Not equal.
  • C. An UnsupportedOperationException is thrown at runtime.
  • D. The program replaces only the file attributes and prints Not equal.

Answer: B

Explanation: Assuming there is a file D:\faculty\report.txt then this file will be copied and will be replacing

Which concept allows generic collections to interoperate with java code that defines collections that use rawtypes?

  • A. bytecode manipulation
  • B. casting
  • C. autoboxing
  • D. auto-unboxing
  • E. type erasure

Answer: E

Explanation: The type erasure of its leftmost bound, or type Object if no bound was specified. Examples:
type parameters type erasure List<String> List Map.Entry<String,Long> Map.Entry
<T extends Cloneable & Comparable<T>> Cloneable
<T extends Object & Comparable<T>> Object
<T> T[] toArray(T[] a) Object[] toArray(Object[] a)
The type erasure process can be imagined as a translation from generic Java source code back into regularJava code. In reality the compiler is more efficient and translates directly to Java byte code. But the byte codecreated is equivalent to the non-generic Java code.

Which two statements are true about RowSet subinterfaces?

  • A. A JdbcRowSet object provides a JavaBean view of a result set.
  • B. A CachedRowSet provides a connected view of the database.
  • C. A FilteredRowSet object filter can be modified at any time.
  • D. A WebRowSet returns JSON-formatted data.

Answer: AC

Explanation: A: a JdbcRowSet object can be one of the Beans that a tool makes available for composing an application.
Because a JdbcRowSet is a connected RowSet, that is, it continually maintains its connection to a databaseusing a JDBC technology-enabled driver, it also effectively makes the driver a JavaBeans component.
C: The FilteredRowSet range criterion can be modified by applying a new Predicate object to the
FilteredRowSet instance at any time. This is possible if no additional references to the FilteredRowSet objectare detected. A new filter has an immediate effect on criterion enforcement within the FilteredRowSet object,and all subsequent views and updates will be subject to similar enforcement.
Reference: javax.sql Interface RowSet

1Z0-804 dumps exhibit
What is the result?

  • A. Nice to see you,be fine
  • B. Nice,see you,be fine
  • C. Nice,see you, to, be fine
  • D. Nice, see you, be fine
  • E. Nice to see y, u, be fine

Answer: A

Explanation: The text ",to," is replaced by the ","

Given the code fragment:
1Z0-804 dumps exhibit
Assume that the SQL query matches one record. What is the result of compiling and executing this code?

  • A. The code prints Error.
  • B. The code prints the employee ID.
  • C. Compilation fails due to an error at line 13.
  • D. Compilation fails due to an error at line 14.

Answer: A

Explanation: The code compiles fine.
A: prints Error: fehlt !! Fehlermeldung: Before start of result set mit Aufruf : The code would run fine.
public int getInt(String columnName) throws SQLException
Retrieves the value of the designated column in the current row of this ResultSet object as an int in the Javaprogramming language

Given the directory structure that contains three directories: company, Salesdat, and Finance:
- Salesdat
* Target.dat
- Finance
* Salary.dat
* Annual.dat
And the code fragment:
1Z0-804 dumps exhibit
If Company is the current directory, what is the result?

  • A. Prints only Annual.dat
  • B. Prints only Salesdat, Annual.dat
  • C. Prints only Annual.dat, Salary.dat, Target.dat
  • D. Prints at least Salesdat, Annual.dat, Salary.dat, Target.dat

Answer: A

Explanation: IF !! return FileVisitResult.CONTINUE;
The pattern *dat will match the directory name Salesdat and it will also match the file Annual.dat.
It will not be matched to Target.dat which is in a subdirectory.

1Z0-804 dumps exhibit
Which two are true?

  • A. A runtime exception is thrown on line 9.
  • B. No output is produced.
  • C. Greeting is printed once.
  • D. Greeting is printed twice.
  • E. No new threads of execution are started within the main method.
  • F. One new thread of execution is started within the main method.
  • G. Two new threads of execution are started within the main method.

Answer: CE

Explanation: Thread t2 is executed. Execution of T2 starts executionen of t1. Greeting is printed during theexecution of t1.

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