Verified 1Z0-804 Free Practice Questions 2019

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Online 1Z0-804 free questions and answers of New Version:

NEW QUESTION 1
Which method would you supply to a class implementing the Callable interface?

  • A. callable ()
  • B. executable ()
  • C. call ()
  • D. run ()
  • E. start ()

Answer: C

Explanation: public interface Callable<V>
A task that returns a result and may throw an exception. Implementors define a single method with noarguments called call.
Note:
Interface Callable<V> Type Parameters:
V - the result type of method call
The Callable interface is similar to Runnable, in that both are designed for classes whose instances arepotentially executed by another thread. A Runnable, however, does not return a result and cannot throw achecked exception.
The Executors class contains utility methods to convert from other common forms to Callable classes.
Reference:java.util.concurrent

NEW QUESTION 2
Given the integer implements comparable:
1Z0-804 dumps exhibit
What is the result?

  • A. 41
  • B. 12
  • C. 32
  • D. 21
  • E. 23

Answer: D

Explanation: binarySearch
public static <T> int binarySearch(List<? extends Comparable<? super T>> list, T key) Searches the specified list for the specified object using the binary search algorithm.
The list must be sorted into ascending order according to the natural ordering of its elements (as by the sort(List) method) prior to making this call. If it is not sorted, the results are undefined.
Parameters:
list - the list to be searched.
key - the key to be searched for. Returns:
the index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1).

NEW QUESTION 3
Given the code fragment:
1Z0-804 dumps exhibit
What is the result?

  • A. M001, ,
  • B. M001, null, null
  • C. M001, Sam,
  • D. M001, Sam, null
  • E. M001, Sam, ABC Inc (Frage unvolständig!!!)
  • F. Compilation fails
  • G. A NullPointerException is thrown at runtime

Answer: E

NEW QUESTION 4
Given these facts about Java types in an application:
- Type x is a template for other types in the application.
- Type x implements dostuff ().
- Type x declares, but does NOT implement doit().
- Type y declares doOther() .
- Which three are true?

  • A. Type y must be an interface.
  • B. Type x must be an abstract class.
  • C. Type y must be an abstract class.
  • D. Type x could implement or extend from Type y.
  • E. Type x could be an abstract class or an interface.
  • F. Type y could be an abstract class or an interface.

Answer: BDF

Explanation: Unlike interfaces, abstract classes can contain fields that are not static and final, and they can containimplemented methods. Such abstract classes are similar to interfaces, except that they provide a partialimplementation, leaving it to subclasses to complete the implementation. If an abstract class contains onlyabstract method declarations, it should be declared as an interface instead.
Note:
An interface in the Java programming language is an abstract type that is used to specify an interface (in thegeneric sense of the term) that classes must implement. Interfaces are declaredusing the interface keyword,and may only contain method signature and constant declarations (variable declarations that are declared tobe both static and final). An interface maynever contain method definitions.
Note 2: an abstract class is a class that is declared abstract--it may or may not include abstract methods.Abstract classes cannot be instantiated, but they can be subclassed. An abstract method is a method that isdeclared without an implementation (without braces, and followed by a semicolon)

NEW QUESTION 5
Given the interface:
Public interface Idgenerator { int getNextId();
}
Which class implements IdGenerator in a thread-safe manner, so that no threads can get a duplicate id valuecurrent access?

  • A. Public class generator Implements IdGenerator { Private AtomicInteger id = new AtomicInteger (0); return id.incrementAndget();}}
  • B. Public class Generator Implements idGenerator { private int id = 0;return ++id;}}
  • C. Public class Generator Implements IdGenerator { private volatile int Id = 0;return ++Id;}
  • D. Public class Generator Implements IdGenerator { private int id = 0;public int getNextId() { synchronized (new Generator()) { return ++id;}}}
  • E. Public class Generator Implements IdGenerator { private int id = 0;public int getnextId() { synchronized (id) { return ++id;}}}

Answer: D

Explanation: Code that is safe to call by multiple threads simultaneously is called thread safe. If a piece of code is threadsafe, then it contains no race conditions. Race condition only occur when multiple threads update sharedresources. Therefore it is important to know what resources Java threads share when executing.
In Java you can mark a method or a block of code as synchronized. Synchronized blocks can be used to avoidrace conditions.
A, B, C : false: wrong Implementation ( missing int getNextId(); ) E: false: synchronized (mutex Object! not Simple Data Type)

NEW QUESTION 6
Given:
1Z0-804 dumps exhibit
What is the result?

  • A. Up Down
  • B. Up Up
  • C. Up null
  • D. Compilation fails
  • E. An exception is thrown at runtime

Answer: D

Explanation: Exception in thread "main" java.lang.ExceptionInInitializerError at garden.Garden.main Caused by: java.lang.RuntimeException: Uncompilable source code - garden.Plant is not abstract and doesnot override abstract method growthDirection() in garden.Plant

NEW QUESTION 7
How many Threads are created when passing task to an Executor instance?

  • A. A new Thread is used for each task.
  • B. A number of Threads equal to the number of CPUs Is used to execute tasks.
  • C. A single Thread Is used to execute all tasks.
  • D. A developer-defined number of Threads is used to execute tasks.
  • E. A number of Threads determined by system load is used to execute tasks.
  • F. The method used to obtain the Executor determines how many Threads are used to execute tasks.

Answer: F

Explanation: The Executor interface provides a single method, execute, designed to be a drop-in replacementfor a common thread-creation idiom. If r is a Runnable object, and e is an Executor object you can replace(new Thread(r)).start();
with e.execute(r);
However, the definition of execute is less specific. The low-level idiom creates a new thread and launches it
immediately. Depending on the Executor implementation, execute may do the same thing, but is more likely to
use an existing worker thread to run r, or to place r in a queue to wait for a worker thread to become available.
Reference: The Java Tutorial,The Executor Interface

NEW QUESTION 8
ITEM Table
* ID, INTEGER: PK
* DESCRIP, VARCHAR(100)
* PRICE, REAL
* QUALITY, INTEGER
And given the code fragment (assuming that the SQL query is valid):
1Z0-804 dumps exhibit
What is the result of compiling and executing this code?

  • A. An exception is thrown at runtime
  • B. Compile fails
  • C. The code prints Error
  • D. The code prints information about Item 110

Answer: C

Explanation: Tricky:
Compiles successfully ! Not B !
D is correct, if Column Quantity instead of Quality
Table Item Column Quality --- System.out.println("Quantity: " + rs.getInt("Quantity")); wenn jedoch so gewollt: die Zeile gibt Error aus (die anderen funktionieren) !!!
The connection conn is not defined. The code will not compile.

NEW QUESTION 9
Given:
1Z0-804 dumps exhibit
What is the result?

  • A. 1 1 1 1 1
  • B. 1 2 3 4 5
  • C. 0 1 2 3 4
  • D. 0 1 4 3 4

Answer: A

Explanation: first for-loop set 0 0 0 0 0
second for-loop increments each to 1 1 1 1 1
if condition is not given

NEW QUESTION 10
Given:
1Z0-804 dumps exhibit
What is the result?

  • A. Cue sports, Cue sports
  • B. Compilation fails at line 9
  • C. Compilation fails at line 11
  • D. Compilation fails at line 12
  • E. Compilation fails at line 13

Answer: B

Explanation: Class Snooker is public. Should be declared in a separate file. // Line 9 getCategory() >>> GetCategory() Line 13

NEW QUESTION 11
- Index.htm
- Service.html
- Logo.gif
- Title.jpg
And the code fragment:
1Z0-804 dumps exhibit
What is the result, if doc is present in the current directory?

  • A. No output is produced.
  • B. index.htm
  • C. index.htm userguide.txt logo.gif
  • D. index.htm service.html userguide.txt logo.gif

Answer: A

Explanation: The Glob search expression is defined through "glob:*.htm, html, xml" The correct answer is A
The glob is trying to match all the string. The correct way is
glob:*.{htm,html,xml}
and then would be found: Index.htm
Service.html

NEW QUESTION 12
Given:
1Z0-804 dumps exhibit
What is the result?

  • A. Compilation fails.
  • B. 78class java.lang.Array.IndexOutOfBoundException
  • C. class MarkOutOfBoundException
  • D. class java.lang.arrayIndexOutOfBoundException

Answer: A

Explanation: The exception MarkOutOfBoundsException is already caught by the alternative ArrayIndexOutOfBoundsException

NEW QUESTION 13
Given the class?
1Z0-804 dumps exhibit
What is the result?

  • A. Jane Doe John Doe Joe Shmoe
  • B. John Doe Jane Doe Joe Shmoe
  • C. Joe Shmoe John Doe Jane Doe
  • D. Joe Shmoe Jane Doe John Doe
  • E. Jane Doe Joe Shmoe John Doe
  • F. John Doe Joe Shmoe Jane Doe

Answer: A

Explanation: The list will be sorted alphabetically (Lastname / Firstname). first sorted by Lastname
if Lastname equals, sorted by firstname Output will be:
Jane Doe John Doe Joe Shmoe

NEW QUESTION 14
Given:
1Z0-804 dumps exhibit
What is the result?

  • A. tolting cantering tolting
  • B. cantering cantering cantering
  • C. compilation fails
  • D. an exception is thrown at runtime

Answer: C

Explanation: Compiler says: Cannot reduce the visibility of the inherited method from Rideable. müssen PUBLIC sein
public String ride() { return "cantering "; } public String ride() { return "tolting "; }
if this is given then the result would be: A : tolting cantering tolting

NEW QUESTION 15
Given:
1Z0-804 dumps exhibit
What is the result?

  • A. Compilation fails at line 9
  • B. Compilation fails at line 10
  • C. Compilation fails at line 5
  • D. Compilation fails at line 3
  • E. Compilation succeeds

Answer: B

NEW QUESTION 16
Given:
1Z0-804 dumps exhibit
Which statement, inserted at line 8, enables the code to compile?

  • A. new Task().new Counter().increment();
  • B. new Task().Counter().increment();
  • C. new Task.Counter().increment();
  • D. Task.Counter().increment();
  • E. Task.Counter.increment();

Answer: C

NEW QUESTION 17
Give:
1Z0-804 dumps exhibit
What is the likely result?

  • A. The program produces the correct result, with similar performance to the original.
  • B. The program produces the correct result, with performance degraded to the equivalent of being singlethreaded.
  • C. The program produces an incorrect result.
  • D. The program goes into an infinite loop.
  • E. An exception is thrown at runtime.
  • F. The program produces the correct result, with better performance than the original.

Answer: D

Explanation: join() does not proceed until the task's result has been computed. Here we start to wait beforedoing the computing. The code will not finish.

NEW QUESTION 18
Which three are true?

  • A. A setAutoCommit (False) method invocation starts a transaction context.
  • B. An instance of Savepoint represents a point in the current transaction context.
  • C. A rollback () method invocation rolls a transaction back to the last savepoint.
  • D. A rollback () method invocation releases any database locks currently held by this connection object.
  • E. After calling rollback (mysavepoint), you must close the savepoint object by calling mySavepoint.close() .

Answer: ABC

Explanation: A:The way to allow two or more statements to be grouped into a transaction is to disable the auto-commitmode. After the auto-commit mode is disabled, no SQL statements are committed until you call the methodcommit explicitly. All statements executed after the previous call to the method commit are included in thecurrent transaction and committed together as a unit.
Note:When a connection is created, it is in auto-commit mode. This means that each individual SQL statementis treated as a transaction and is automatically committed right after it is executed. (To be more precise, thedefault is for a SQL statement to be committed when it is completed, not when it is executed. A statement iscompleted when all of its result sets and update counts have been retrieved. In almost all cases, however, astatement is completed, and therefore committed, right after it is executed.)
B:The method Connection.setSavepoint, sets a Savepoint object within the current transaction. The
Connection.rollback method is overloaded to take a Savepoint argument. When a transaction is rolled back toa savepoint all changes made after that savepoint are undone. C: calling the method rollback terminates a transaction and returns any values that were modified to theirprevious values. If you are trying to execute one or more statements in a transaction and get a SQLException, call the method rollback to end the transaction and start the transaction all over again.

NEW QUESTION 19
Given:
1Z0-804 dumps exhibit
Which two classes correctly override the getDepth method?

  • A. public class deep extends Deeper { protected Integer getDepth(){return 5;}}
  • B. public class deep extends Deeper { public Double getDepth() {return 5d;}}
  • C. public class deep extends Deeper { public String getDepth () {}}
  • D. public class deep extends Deeper { public Long getDepth (int d) {return 5L;}}
  • E. public class deep extends Deeper { public Short getDepth () {return 5;}}

Answer: AE

Explanation: Note: The abstract class Number is the superclass of classes Byte, Double, Float, Integer, Long, and Short.
Subclasses of Number must provide methods to convert the represented numeric value to byte, double, float, int, long, and short.
When class C extends B, we say that C is a "subclass" of B, and B is the "superclass" of C. This is called inheritence, because C inherited from B.

NEW QUESTION 20
Given:
1Z0-804 dumps exhibit
What two changes, made independently, will enable the code to compile?

  • A. Change the signature of Account to: public class Account.
  • B. Change the signature of CheckingAccount to: public abstract CheckingAccount
  • C. Implement private methods for deposit and withdraw in CheckingAccount.
  • D. Implement public methods for deposit and withdraw in CheckingAccount.
  • E. Change Signature of checkingAccount to: CheckingAccount implements Account.
  • F. Make Account an interface.

Answer: BD

Explanation: Compiler say:
- Der Typ CheckingAccount muss die übernommene abstrakte Methode Account.deposit(double) implementieren
- Der Typ CheckingAccount muss die übernommene abstrakte Methode Account.withdraw(double) implementieren
ODER
Typ CheckingAccount als abstract definieren

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