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A practice test for Java level 1 at Gwinnett Technical College

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Java Practice 3

Frage 1 von 105

1

Which class do you use to write data into a text file?

Wähle eine der folgenden:

  • System

  • PrintWriter

  • Scanner

  • File

Erklärung

Frage 2 von 105

1

Which of the following statements is false?

Wähle eine der folgenden:

  • The smallest data item a computer can assume is the value 0 or the value 1.

  • The term "bit" is short for "byte digit."

  • Java uses the Unicode character set.

  • A record is typically composed of several fields.

Erklärung

Frage 3 von 105

1

What is the return value of "SELECT".substring(0, 5)?

Wähle eine der folgenden:

  • "SELECT"

  • "SELE"

  • "SELEC"

  • "ELECT"

Erklärung

Frage 4 von 105

1

Which of the following assignment statements is incorrect? (Choose all that apply.)

Wähle eine oder mehr der folgenden:

  • i == j == k == 1;

  • i = j = k = 1;

  • i = 1; j = 1; k = 1;

  • i = 1 = j = 1 = k = 1;

Erklärung

Frage 5 von 105

1

An argument type followed by a(n) __________________ in a method's parameter list indicates that the method receives a variable number of arguments of that particular type.

Wähle eine der folgenden:

  • square brackets ([]).

  • ellipsis ().

  • varargs keyword.

  • All of the above are acceptable to indicate a variable number of arguments.

Erklärung

Frage 6 von 105

1

Which of the following statements creates a multidimensional array with 3 rows, where the first row contains 1 element, the second row contains 4 elements and the final row contains 2 elements?

Wähle eine der folgenden:

  • int[][] items = { { 1, null, null, null }, { 2, 3, 4, 5 }, { 6, 7, null, null } };.

  • int[][] items = { { 1 }, { 2, 3, 4, 5 }, { 6, 7 } };.

  • int[][] items = { { 1 }, { 2, 3, 4, 5 }, { 6, 7 }, {} );.

  • int[][] items = { { 1 }, { 4 }, { 2 } };.

Erklärung

Frage 7 von 105

1

What modifier should you use on the members of a class so that they are not accessible to another class in a different package, but are accessible to any subclasses in any package?

Wähle eine der folgenden:

  • protected

  • public

  • private

  • Use the default modifier.

Erklärung

Frage 8 von 105

1

Which of the following statements are true about an immutable object? (Choose all that apply.)

Wähle eine oder mehr der folgenden:

  • The contents of an immutable object cannot be modified.

  • An immutable object contains no mutator methods.

  • All properties of an immutable object must be of primitive types.

  • All properties of an immutable object must be private.

  • An object type property in an immutable object must also be immutable.

Erklärung

Frage 9 von 105

1

What is the output of the following code?
public class Test {
public static void main(String[ ] args) {
String s1 = new String("Welcome to Java");
String s2 = s1;

s1 += "and Welcome to HTML";

if (s1 == s2)
System.out.println("s1 and s2 reference to the same String object");
else
System.out.println("s1 and s2 reference to different String objects");
}
}

Wähle eine der folgenden:

  • s1 and s2 reference to different String objects

  • s1 and s2 reference to the same String object

Erklärung

Frage 10 von 105

1

Which of the following is not an algorithm?

Wähle eine der folgenden:

  • A recipe.

  • Operating instructions.

  • Textbook index.

  • Shampoo instructions (lather, rinse, repeat).

Erklärung

Frage 11 von 105

1

Which of the following segments is a proper way to call the method readData four times?

Wähle eine der folgenden:

  • double k;

    k = 0.0;


    while (k != 4) 
{

    readData();

    k = k + 1;

    } // end while

  • int i;

    i = 0;


    while ( i <= 4 ) 
{

    readData();

    i = i + 1;

    } // end while

  • int i;

    i = 0;


    while ( i < 4 ) 
{

    readData();

    } // end while

  • int i;

    i = 0;


    while ( i < 4 ) 
{
    readData();

    i = i + 1;

    } // end while

Erklärung

Frage 12 von 105

1

Which method returns an array of the enum’s constants?

Wähle eine der folgenden:

  • values.

  • getValues.

  • constants.

  • getConstants.

Erklärung

Frage 13 von 105

1

An anonymous String:

Wähle eine der folgenden:

  • has no value.

  • is a string literal.

  • can be changed.

  • none of the above.

Erklärung

Frage 14 von 105

1

What exception type does the following program throw?

public class Test {
public static void main(String[ ] args) {
Object o = null;
System.out.println(o);
}
}

Wähle eine der folgenden:

  • StringIndexOutOfBoundsException

  • NullPointerException

  • ArrayIndexOutOfBoundsException

  • No exception

  • ArithmeticException

Erklärung

Frage 15 von 105

1

Overloaded methods always have the same _________.

Wähle eine der folgenden:

  • method name.

  • return type.

  • number of parameters.

  • order of the parameters.

Erklärung

Frage 16 von 105

1

All import declarations must be placed

Wähle eine der folgenden:

  • inside the class declaration’s body.

  • before the class declaration.

  • after the class declaration.

  • all of the above will work.

Erklärung

Frage 17 von 105

1

The preferred way to traverse a two-dimensional array is to use _______ .

Wähle eine der folgenden:

  • a do while statement.

  • a for statement.

  • two nested for statements.

  • three nested for statements.

Erklärung

Frage 18 von 105

1

Which of the following will count down from 10 to 1 correctly?

Wähle eine der folgenden:

  • for ( int j = 10; j <= 1; j++ )

  • for ( int j = 1; j <= 10; j++ )

  • for ( int j = 10; j > 1; j-- )

  • for ( int j = 10; j >= 1; j-- )

Erklärung

Frage 19 von 105

1

Which of the following does not contribute to improved software reusability?

Wähle eine der folgenden:

  • Quickly creating new class libraries without testing them thoroughly.

  • Licensing schemes and protection mechanisms.

  • Descriptions of classes that allow programmers to determine whether a class fits their needs.

  • Cataloging schemes and browsing mechanisms.

Erklärung

Frage 20 von 105

1

What code may be filled in the blank without causing syntax or runtime errors:

public class Test {
java.util.Date date;

public static void main(String[ ] args) {
Test test = new Test();
System.out.println(________);
}
}

Wähle eine der folgenden:

  • date

  • test.date

  • date.toString()

  • test.date.toString()

Erklärung

Frage 21 von 105

1

Which of the following is a valid identifier? (Choose all that apply.)

Wähle eine oder mehr der folgenden:

  • class

  • radius

  • 9X

  • 8+9

  • $343

Erklärung

Frage 22 von 105

1

When should a program explicitly use the this reference?

Wähle eine der folgenden:

  • Accessing a private variable.

  • Accessing a public variable.

  • Accessing a local variable.

  • Accessing a field that is shadowed by a local variable.

Erklärung

Frage 23 von 105

1

Variables that are shared by every instances of a class are ________.

Wähle eine der folgenden:

  • class variables

  • public variables

  • private variables

  • instance variables

Erklärung

Frage 24 von 105

1

Which of the following is true? (Choose all that apply.)

Wähle eine oder mehr der folgenden:

  • The capacity of a string buffer can be automatically adjusted.

  • You can reverse the characters in a string buffer.

  • You can add characters into a string buffer.

  • You can delete characters into a string buffer.

Erklärung

Frage 25 von 105

1

Which of the following is arranged in increasing size order?

Wähle eine der folgenden:

  • field, bit, file, record.

  • byte, file, database, record.

  • byte, field, file, record.

  • bit, field, record, file.

Erklärung

Frage 26 von 105

1

Which method can be used to read a whole line from the file?

Wähle eine der folgenden:

  • nextInt

  • next

  • nextLine

  • nextDouble

Erklärung

Frage 27 von 105

1

-24 % -5 is ________.

Wähle eine der folgenden:

  • 3

  • -3

  • 4

  • -4

  • 0

Erklärung

Frage 28 von 105

1

Analyze the following code.

public class Test {
public static void main(String[ ] args) {
int month = 09;
System.out.println("month is " + month);
}
}

Wähle eine der folgenden:

  • The program displays month is 9.0

  • The program displays month is 9

  • The program displays month is 09

  • The program has a syntax error, because 09 is an incorrect literal value.

Erklärung

Frage 29 von 105

1

A decision symbol in an activity diagram takes the shape of a ________.

Wähle eine der folgenden:

  • Diamond.

  • Rectangle.

  • Circle.

  • Triangle.

Erklärung

Frage 30 von 105

1

Analyze the following code.

// Program 1:
public class Test {
public static void main(String[ ] args) {
Object a1 = new A();
Object a2 = new A();
System.out.println(a1.equals(a2));
}
}

class A {
int x;

public boolean equals(Object a) {
return this.x == ((A)a)x;
}
}

// Program 2:
public class Test {
public static void main(String[ ] args) {
Object a1 = new A();
Object a2 = new A();
System.out.println(a1.equals(a2));
}
}

class A {
int x;

public boolean equals(A a) {
return this.x == a.x;
}
}

Wähle eine der folgenden:

  • Program 1 displays true and Program 2 displays true

  • Program 1 displays true and Program 2 displays false

  • Program 1 displays false and Program 2 displays true

  • Program 1 displays false and Program 2 displays false

Erklärung

Frage 31 von 105

1

Which correctly creates an array of five empty Strings?

Wähle eine der folgenden:

  • String[ ] a = new String [5];

  • String[ ] a = new String [5]; for (int i = 0; i < 5; a[i++] = null);

  • String[ ] a = {"", "", "", "", ""};

  • String[5] a;

Erklärung

Frage 32 von 105

1

Which of the following are Java keywords?

Wähle eine der folgenden:

  • instanceof

  • instanceOf

  • casting

  • cast

Erklärung

Frage 33 von 105

1

When you return an array from a method, the method returns ________.

Wähle eine der folgenden:

  • a copy of the array

  • the reference of the array

  • a copy of the first element

  • the length of the array

Erklärung

Frage 34 von 105

1

What is the output of the following code?

public class Test {
public static void main(String[ ] args) {
String s1 = new String("Welcome to Java!");
String s2 = new String("Welcome to Java!");

if (s1 == s2)
System.out.println("s1 and s2 reference to the same String object");
else
System.out.println("s1 and s2 reference to different String objects");
}
}

Wähle eine der folgenden:

  • s1 and s2 reference to different String objects

  • s1 and s2 reference to the same String object

Erklärung

Frage 35 von 105

1

Which of the following should usually be private?

Wähle eine der folgenden:

  • Methods.

  • Constructors.

  • Variables (or fields).

  • All of the above.

Erklärung

Frage 36 von 105

1

When an argument is passed by reference:

Wähle eine der folgenden:

  • a copy of the argument’s value is passed to the called method.

  • changes to the argument do not affect the original variable’s value in the caller.

  • the called method can access the argument’s value in the caller directly and modify that data.

  • the original value is removed from memory.

Erklärung

Frage 37 von 105

1

How many times will the following code print "Welcome to Java"?

int count = 0;
do {
System.out.println("Welcome to Java");
} while (count++ < 10);

Wähle eine der folgenden:

  • 10

  • 8

  • 0

  • 9

  • 11

Erklärung

Frage 38 von 105

1

Suppose TestCircle and Circle in Listing 7.1 in the textbook are in two separate files named TestCircle.java and Circle.java, respectively. What is the outcome of compiling TestCircle.java and then Circle.java?

Wähle eine der folgenden:

  • Only TestCircle.java compiles.

  • Both compile fine.

  • Neither compiles successfully.

  • Only Circle.java compiles.

Erklärung

Frage 39 von 105

1

The default value for data field of a boolean type, numeric type, object type is ________, respectively.

Wähle eine der folgenden:

  • true, 1, Null

  • true, 1, null

  • false, 0, null

  • false, 1, null

  • true, 0, null

Erklärung

Frage 40 von 105

1

Which of the following is not a valid Java identifier?

Wähle eine der folgenden:

  • my Value

  • $_AAA1

  • width

  • m_x

Erklärung

Frage 41 von 105

1

Consider the array:

s[ 0 ] = 7

s[ 1 ] = 0

s[ 2 ] = -12

s[ 3 ] = 9

s[ 4 ] = 10

s[ 5 ] = 3

s[ 6 ] = 6

The value of s[ s[ 6 ] - s[ 5 ] ] is

Wähle eine der folgenden:

  • 0

  • 3

  • 9

Erklärung

Frage 42 von 105

1

Which of the following is not a superclass/subclass relationship?

Wähle eine der folgenden:

  • Ford/Taurus.

  • University/Brown University.

  • Sailboat/Tugboat.

  • Country/USA.

Erklärung

Frage 43 von 105

1

Which of the following is the shape of an action-state symbol?

Wähle eine der folgenden:

  • Diamond.

  • Circle.

  • Rectangle with left and right sides replaced with arcs curving outward.

  • Rounded rectangle.

Erklärung

Frage 44 von 105

1

Analyze the following code:

public class Test1 {
public static void main(String[ ] args) {
xMethod(new double[ ]{3, 3});
xMethod(new double[5]);
xMethod(new double[3]{1, 2, 3});
}

public static void xMethod(double[ ] a) {
System.out.println(a.length);
}
}

Wähle eine der folgenden:

  • The program has a compile error because xMethod(new double[ ]{3, 3}) is incorrect.

  • The program has a compile error because xMethod(new double[3]{1, 2, 3}) is incorrect.

  • The program has a compile error because xMethod(new double[5]) is incorrect.

  • The program has a runtime error because a is null.

Erklärung

Frage 45 von 105

1

What is output by the following Java code segment?

int temp;
temp = 180;

if ( temp > 90 )
{
System.out.println( "This porridge is too hot." );

// cool down
temp = temp – ( temp > 150 ? 100 : 20 );
} // end if
else
{
if ( temp < 70 )
{
System.out.println("This porridge is too cold.");

// warm up
temp = temp + (temp < 50 ? 30 : 20);
} // end if
} // end else

if ( temp == 80 )
System.out.println( "This porridge is just right!" );

Wähle eine der folgenden:

  • This porridge is too hot.

  • This porridge is too cold. This porridge is just right!

  • This porridge is just right!

  • None of the above.

Erklärung

Frage 46 von 105

1

A method must declare to throw ________.

Wähle eine der folgenden:

  • Error

  • unchecked exceptions

  • checked exceptions

  • RuntimeException

Erklärung

Frage 47 von 105

1

What is displayed on the console when running the following program?

class Test {
public static void main(String[ ] args) {
try {
System.out.println("Welcome to Java");
int i = 0;
int y = 2/i;
System.out.println("Welcome to Java");
}
catch (RuntimeException ex) {
System.out.println("Welcome to Java");
}
finally {
System.out.println("End of the block");
}

System.out.println("End of the block");
}
}

Wähle eine der folgenden:

  • The program displays Welcome to Java three times followed by End of the block.

  • The program displays Welcome to Java two times followed by End of the block two times.

  • The program displays Welcome to Java two times followed by End of the block.

  • You cannot catch RuntimeException errors.

Erklärung

Frage 48 von 105

1

Which syntax imports all static members of class Math?

Wähle eine der folgenden:

  • static import java.lang.Math.*.

  • import static java.lang.Math.*.

  • static import java.lang.Math.

  • import static java.lang.Math.

Erklärung

Frage 49 von 105

1

The StringBuilder methods ________ not only change the contents of a string buffer, but also returns a reference to the string buffer. (Choose all that apply.)

Wähle eine oder mehr der folgenden:

  • delete

  • replace

  • append

  • reverse

  • insert

Erklärung

Frage 50 von 105

1

Every letter in a Java keyword is in lowercase.

Wähle eine der folgenden:

  • true

  • false

Erklärung

Frage 51 von 105

1

Math.pow(2, 3) returns ________.

Wähle eine der folgenden:

  • 8.0

  • 9.0

  • 8

  • 9

Erklärung

Frage 52 von 105

1

Which of the following classes cannot be extended?

Wähle eine der folgenden:

  • class A { protected A();}

  • class A { private A();}

  • final class A { }

  • class A { }

Erklärung

Frage 53 von 105

1

In an expression containing values of the types int and double, the ________ values are ________ to ________ values for use in the expression.

Wähle eine der folgenden:

  • int, promoted, double.

  • int, demoted, double.

  • double, promoted, int.

  • double, demoted, int.

Erklärung

Frage 54 von 105

1

Having a this reference allows:

Wähle eine der folgenden:

  • a method to refer explicitly to the instance variables and other methods of the object on which the method was called.

  • a method to refer implicitly to the instance variables and other methods of the object on which the method was called.

  • an object to reference itself.

  • All of the above.

Erklärung

Frage 55 von 105

1

An instance of ________ describes programming errors, such as bad casting, accessing an out-of-bounds array, and numeric errors..

Wähle eine der folgenden:

  • Exception

  • NumberFormatException

  • Error

  • RuntimeException

  • Throwable

Erklärung

Frage 56 von 105

1

Analyze the following code.

// Program 1
public class Test {
public static void main(String[ ] args) {
Object a1 = new A();
Object a2 = new A();
System.out.println(((A)a1).equals((A)a2));
}
}

class A {
int x;

public boolean equals(A a) {
return this.x == a.x;
}
}

// Program 2
public class Test {
public static void main(String[ ] args) {
A a1 = new A();
A a2 = new A();
System.out.println(a1.equals(a2));
}
}

class A {
int x;

public boolean equals(A a) {
return this.x == a.x;
}
}

Wähle eine der folgenden:

  • Program 1 displays false and Program 2 displays false

  • Program 1 displays true and Program 2 displays true

  • Program 1 displays true and Program 2 displays false

  • Program 1 displays false and Program 2 displays true

Erklärung

Frage 57 von 105

1

How many significant digits does a double variable have?

Wähle eine der folgenden:

  • 7.

  • 8.

  • 14.

  • 15.

Erklärung

Frage 58 von 105

1

In Java graphics, coordinate units are measured in ________.

Wähle eine der folgenden:

  • dots.

  • pixels.

  • points.

  • inches.

Erklärung

Frage 59 von 105

1

Which code fragment would correctly identify the number of arguments passed via the command line to a Java application, excluding the name of the class that is being invoked?

Wähle eine der folgenden:

  • int count = 0; while (args[count] != null) count ++;

  • int count = args.length;

  • int count = args.length - 1;

  • int count=0; while (!(args[count].equals(""))) count ++;

Erklärung

Frage 60 von 105

1

The ________ method returns a raised to the power of b.

Wähle eine der folgenden:

  • Math.pow(a, b)

  • Math.pow(b, a)

  • Math.power(a, b)

  • Math.exponent(a, b)

Erklärung

Frage 61 von 105

1

Which of the following will not produce a compiler error?

Wähle eine der folgenden:

  • Changing the value of a constant after it is declared.

  • Changing the value at a given index of an array after it is created.

  • Using a final variable before it is initialized.

  • All of the above will produce compiler errors.

Erklärung

Frage 62 von 105

1

The default equals implementation determines:

Wähle eine der folgenden:

  • whether two references refer to the same object in memory.

  • whether two references have the same type.

  • whether two objects have the same instance variables.

  • whether two objects have the same instance variable values.

Erklärung

Frage 63 von 105

1

Analyze the following code:

public class Test {
public static void main(String[ ] args) {
B b = new B();
b.m(5);
System.out.println("i is " + b.i);
}
}

class A {
int i;

public void m(int i) {
this.i = i;
}
}

class B extends A {
public void m(String s) {
}
}

Wähle eine der folgenden:

  • The program has a compilation error, because m is overridden with a different signature in B.

  • The method m is not overridden in B. B inherits the method m from A and defines an overloaded method m in B.

  • The program has a runtime error on b.i, because i is not accessible from b.

  • The program has a compilation error, because b.m(5) cannot be invoked since the method m(int) is hidden in B.

Erklärung

Frage 64 von 105

1

What is the output of the following program?

import java.util.Date;

public class Test {
public static void main(String[ ] args) {
Date date = new Date(1234567);
m1(date);
System.out.print(date.getTime() + " ");

m2(date);
System.out.println(date.getTime());
}

public static void m1(Date date) {
date = new Date(7654321);
}

public static void m2(Date date) {
date.setTime(7654321);
}
}

Wähle eine der folgenden:

  • 7654321 1234567

  • 1234567 7654321

  • 7654321 7654321

  • 1234567 1234567

Erklärung

Frage 65 von 105

1

Given the following method

static void nPrint(String message, int n) {
while (n > 0) {
System.out.print(message);
n--;
}
}

What is the printout of the call nPrint('a', 4)?

Wähle eine der folgenden:

  • aaaa

  • aaa

  • invalid call

  • aaaaa

Erklärung

Frage 66 von 105

1

Which of the following can be used in the expression after keyword case?

A. a constant integral expression.
B. a character constant.
C. a constant.
D. an enumeration constant.

Wähle eine der folgenden:

  • A and B.

  • A and C.

  • B and C.

  • All.

Erklärung

Frage 67 von 105

1

In array items, which expression below accesses the value at row 3 and column 4?

Wähle eine der folgenden:

  • items[ 3 ].[ 4 ].

  • items[ 3[ 4 ] ].

  • items[ 3 ][ 4 ].

  • items[ 3, 4 ].

Erklärung

Frage 68 von 105

1

Which of the following is the correct statement to return JAVA?

Wähle eine der folgenden:

  • String.toUpperCase("Java")

  • "Java".toUpperCase()

  • toUpperCase("Java")

  • "Java".toUpperCase("Java")

Erklärung

Frage 69 von 105

1

Which statement is false?

Wähle eine der folgenden:

  • The actual data representation used within the class is of no concern to the class's clients.

  • Clients generally care about what the class does but not how the class does it.

  • Clients are usually involved in a class's implementation.

  • Hiding the implementation reduces the possibility that clients will become dependent on class-implementation details.

Erklärung

Frage 70 von 105

1

Which of the following is not an arithmetic operator?

Wähle eine der folgenden:

  • +

  • -

  • .

  • %

Erklärung

Frage 71 von 105

1

Which of the following classes is not used for file input?

Wähle eine der folgenden:

  • FileInputStream

  • FileReader

  • ObjectInputStream

  • Formatter

Erklärung

Frage 72 von 105

1

Consider the code segment below.

if ( gender == 1 )
{
if ( age >= 65 )
++seniorFemales;
} // end if

This segment is equivalent to which of the following?

Wähle eine der folgenden:

  • if ( gender == 1 || age >= 65 )

    ++seniorFemales;

  • if ( gender == 1 && age >= 65 )
    ++seniorFemales;

  • if ( gender == 1 AND age >= 65 )

    ++seniorFemales;

  • if ( gender == 1 OR age >= 65 )

    ++seniorFemales;

Erklärung

Frage 73 von 105

1

A final field should also be declared ________ if it is initialized in its declaration.

Wähle eine der folgenden:

  • private.

  • public.

  • protected.

  • static.

Erklärung

Frage 74 von 105

1

The ________ method displays an input dialog for reading a string. (Choose all that apply.)

Wähle eine oder mehr der folgenden:

  • String string = JOptionPane.showInputDialog(null, "Enter a string", "Input Demo", JOptionPane.QUESTION_MESSAGE);

  • String string = JOptionPane.showInputDialog(null, "Enter a string");

  • String string = JOptionPane.showInputDialog("Enter a string");

  • String string = JOptionPane.showInputDialog("Enter a string", "Input Demo", JOptionPane.QUESTION_MESSAGE);

  • String string = JOptionPane.showMessageDialog(null, "Enter a string", "Input Demo", JOptionPane.QUESTION_MESSAGE);

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Frage 75 von 105

1

A default constructor has how many parameters?

Wähle eine der folgenden:

  • 0.

  • 1.

  • 2.

  • Variable.

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Frage 76 von 105

1

The ________ method immediately terminates the program.

Wähle eine der folgenden:

  • System.stop(0);

  • System.halt(0);

  • System.terminate(0);

  • System.exit(0);

  • System.quit(0);

Erklärung

Frage 77 von 105

1

Sentinel-controlled repetition is also known as:

Wähle eine der folgenden:

  • Definite repetition.

  • Indefinite repetition.

  • Multiple repetition.

  • Double repetition.

Erklärung

Frage 78 von 105

1

Polymorphism means ________.

Wähle eine der folgenden:

  • that a class can extend another class

  • that data fields should be declared private

  • that a class can contain another class

  • that a variable of supertype can refer to a subtype object

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Frage 79 von 105

1

Which of the following is not a syntax error?

Wähle eine der folgenden:

  • System.out.println( 'Hello world!' ):

  • System.out.println( "Hello . world!" );

  • System.out.println( "Hello world!" );

  • System.out.println( Hello world! );

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Frage 80 von 105

1

What is k after the following block executes?

{
int k = 2;
nPrint("A message", k);
}
System.out.println(k);

Wähle eine der folgenden:

  • 2

  • 1

  • 0

  • k is not defined outside the block. So, the program has a compile error

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Frage 81 von 105

1

The _________ of a class are also called the public services or the public interface that the class provides to its clients.

Wähle eine der folgenden:

  • public constructors.

  • public instance variables.

  • public methods.

  • All of the above.

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Frage 82 von 105

1

Analyze the following code: (Choose all that apply.)

public class Test {
public static void main(String[ ] args) {
Object a1 = new A();
Object a2 = new Object();
System.out.println(a1);
System.out.println(a2);
}
}

class A {
int x;
public String toString() {
return "A's x is " + x;
}
}

Wähle eine oder mehr der folgenden:

  • When executing System.out.println(a1), the toString() method in the Object class is invoked.

  • When executing System.out.println(a1), the toString() method in the A class is invoked.

  • When executing System.out.println(a2), the toString() method in the Object class is invoked.

  • The program cannot be compiled, because System.out.println(a1) is wrong and it should be replaced by System.out.println(a1.toString());

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Frage 83 von 105

1

What do the following statements do?

double[] array;

array = new double[ 14 ];

Wähle eine der folgenden:

  • Create a double array containing 13 elements.

  • Create a double array containing 14 elements.

  • Create a double array containing 15 elements.

  • Declare but do not create a double array.

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Frage 84 von 105

1

When you invoke a method with a parameter, the value of the argument is passed to the parameter. This is referred to as ________.

Wähle eine der folgenden:

  • pass by name

  • pass by value

  • pass by reference

  • method invocation

Erklärung

Frage 85 von 105

1

Which of following is not a correct method in Character? (Choose all that apply.)

Wähle eine oder mehr der folgenden:

  • isDigit()

  • toLowerCase(char)

  • isLetter(char)

  • toUpperCase()

  • isLetterOrDigit(char)

Erklärung

Frage 86 von 105

1

Given the following classes and their objects:

class C1 {};
class C2 extends C1 {};
class C3 extends C1 {};

C2 c2 = new C2();
C3 c3 = new C3();

Analyze the following statement:

c2 = (C2)((C1)c3);

Wähle eine der folgenden:

  • You will get a runtime error because you cannot cast objects from sibling classes.

  • You will get a runtime error because the Java runtime system cannot perform multiple casting in nested form.

  • c3 is cast into c2 successfully.

  • The statement is correct.

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Frage 87 von 105

1

Every class in Java, except ________, extends an existing class.

Wähle eine der folgenden:

  • Integer.

  • Object.

  • String.

  • Class.

Erklärung

Frage 88 von 105

1

By default, the classpath consists only of the ________. However, the classpath can be modified by providing the ________ option to the javac compiler.

Wähle eine der folgenden:

  • root directory of the package, -d.

  • current directory, -d.

  • root directory of the package, -classpath.

  • current directory, -classpath.

Erklärung

Frage 89 von 105

1

Which of the following is not a compilation error?

Wähle eine der folgenden:

  • Neglecting to initialize a local variable in a method before it is used.

  • Placing a semicolon at the end of the first line of an if statement.

  • Omitting the left and right parenthesis for the condition of an if statement.

  • All are compilation errors.

Erklärung

Frage 90 von 105

1

________ is a simple but incomplete version of a method.

Wähle eine der folgenden:

  • A non-main method

  • A method developed using top-down approach

  • A stub

  • A main method

Erklärung

Frage 91 von 105

1

What is displayed by the following code?

public static void main(String[ ] args) throws Exception {
String[ ] tokens = "Welcome to Java".split("o");
for (int i = 0; i < tokens.length; i++) {
System.out.print(tokens[i] + " ");
}
}

Wähle eine der folgenden:

  • Welcome t Java

  • Welc me t Java

  • Welc me to Java

  • Welcome to Java

Erklärung

Frage 92 von 105

1

Which of the following code segments does not increment val by 3:

Wähle eine der folgenden:

  • val += 3;

  • val = val+1;

    val = val+1;
    val = val+1;

  • c = 3;

    val = val + (c == 3 ? 2 : 3);

  • All of the above increment val by 3.

Erklärung

Frage 93 von 105

1

The import declaration import *; ________.

Wähle eine der folgenden:

  • causes a compilation error.

  • imports all classes in the library.

  • imports the default classes in the library.

  • imports the classes in package java.lang.

Erklärung

Frage 94 von 105

1

An instance of ________ describes system errors. If this type of error occurs, there is little you can do beyond notifying the user and trying to terminate the program gracefully.

Wähle eine der folgenden:

  • RuntimeException

  • Throwable

  • Error

  • Exception

  • NumberFormatException

Erklärung

Frage 95 von 105

1

An instance of ________ describes the errors caused by your program and external circumstances. These errors can be caught and handled by your program.

Wähle eine der folgenden:

  • NumberFormatException

  • Error

  • RuntimeException

  • Throwable

  • Exception

Erklärung

Frage 96 von 105

1

What is the value of result after the following Java statements execute?

int a, b, c, d, result;

a = 4;

b = 12;

c = 37;

d = 51;

result = d % a * c + a % b + a;

Wähle eine der folgenden:

  • 119

  • 51

  • 127

  • 59

Erklärung

Frage 97 von 105

1

When method printf requires multiple arguments, the arguments are separated with ________.

Wähle eine der folgenden:

  • colons (:).

  • semicolons (;).

  • commas (,).

  • periods (.).

Erklärung

Frage 98 von 105

1

Analyze the following statement:

double sum = 0;

for (double d = 0; d<10;) {
d += 0.1;
sum += sum + d;
}

Wähle eine der folgenden:

  • The program compiles and runs fine.

  • The program runs in an infinite loop because d<10 would always be true.

  • The program has a compile error because the control variable in the for loop cannot be of the double type.

  • The program has a compile error because the adjustment is missing in the for loop.

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Frage 99 von 105

1

Suppose x is 1. What is x after x -= 1?

Wähle eine der folgenden:

  • 0

  • 1

  • 2

  • -1

  • -2

Erklärung

Frage 100 von 105

1

Stacks are known as ________ data structures.

Wähle eine der folgenden:

  • FIFO.

  • FILO.

  • LIFO.

  • LILO.

Erklärung

Frage 101 von 105

1

Which statement is true when a superclass has protected instance variables?

Wähle eine der folgenden:

  • A subclass object can assign an invalid value to the superclass’s instance variables, thus leaving an object in an inconsistent state.

  • Subclass methods are more likely to be written so that they depend on the superclass’s data implementation.

  • We may need to modify all the subclasses of the superclass if the superclass implementation changes.

  • All of the above.

Erklärung

Frage 102 von 105

1

If you enter 1 2 3, when you run this program, what will be the output?

import java.util.Scanner;

public class Test1 {
public static void main(String[ ] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter three numbers: ");
double number1 = input.nextDouble();
double number2 = input.nextDouble();
double number3 = input.nextDouble();
// Compute average
double average = (number1 + number2 + number3) / 3;
// Display result
System.out.println(average);
}
}

Wähle eine der folgenden:

  • 1.0

  • 2.0

  • 4.0

  • 3.0

Erklärung

Frage 103 von 105

1

Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following methods will cause the list to become [Beijing, Chicago, Singapore]?

Wähle eine der folgenden:

  • x.add(2, "Chicago")

  • x.add(1, "Chicago")

  • x.add("Chicago")

  • x.add(0, "Chicago")

Erklärung

Frage 104 von 105

1

Which of the following statements are true?

Wähle eine der folgenden:

  • If a file (e.g., c:\temp.txt) does not exist, new File("c:\\temp.txt") creates a new file named c:\temp.txt.

  • If a directory (e.g., c:\liang) does not exist, new File("c:\liang") creates a new directory named c:\liang.

  • If a directory (e.g., c:\liang) does not exist, new File("c:\liang") returns null.

  • If a file (e.g., c:\temp.txt) does not exist, new File("c:\\temp.txt") returns null.

  • None of the above.

Erklärung

Frage 105 von 105

1

The visibility of these modifiers increases in this order:

Wähle eine der folgenden:

  • none (if no modifier is used), private, protected, and public.

  • none (if no modifier is used), protected, private, and public.

  • private, protected, none (if no modifier is used), and public.

  • private, none (if no modifier is used), protected, and public.

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