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Java Practice 3

Beschreibung

A practice test for Java level 1 at Gwinnett Technical College
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Zusammenfassung der Ressource

Frage 1

Frage
Which class do you use to write data into a text file?
Antworten
  • System
  • PrintWriter
  • Scanner
  • File

Frage 2

Frage
Which of the following statements is false?
Antworten
  • 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.

Frage 3

Frage
What is the return value of "SELECT".substring(0, 5)?
Antworten
  • "SELECT"
  • "SELE"
  • "SELEC"
  • "ELECT"

Frage 4

Frage
Which of the following assignment statements is incorrect? (Choose all that apply.)
Antworten
  • i == j == k == 1;
  • i = j = k = 1;
  • i = 1; j = 1; k = 1;
  • i = 1 = j = 1 = k = 1;

Frage 5

Frage
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.
Antworten
  • square brackets ([]).
  • ellipsis ().
  • varargs keyword.
  • All of the above are acceptable to indicate a variable number of arguments.

Frage 6

Frage
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?
Antworten
  • 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 } };.

Frage 7

Frage
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?
Antworten
  • protected
  • public
  • private
  • Use the default modifier.

Frage 8

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

Frage 9

Frage
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"); } }
Antworten
  • s1 and s2 reference to different String objects
  • s1 and s2 reference to the same String object

Frage 10

Frage
Which of the following is not an algorithm?
Antworten
  • A recipe.
  • Operating instructions.
  • Textbook index.
  • Shampoo instructions (lather, rinse, repeat).

Frage 11

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

Frage 12

Frage
Which method returns an array of the enum’s constants?
Antworten
  • values.
  • getValues.
  • constants.
  • getConstants.

Frage 13

Frage
An anonymous String:
Antworten
  • has no value.
  • is a string literal.
  • can be changed.
  • none of the above.

Frage 14

Frage
What exception type does the following program throw? public class Test { public static void main(String[ ] args) { Object o = null; System.out.println(o); } }
Antworten
  • StringIndexOutOfBoundsException
  • NullPointerException
  • ArrayIndexOutOfBoundsException
  • No exception
  • ArithmeticException

Frage 15

Frage
Overloaded methods always have the same _________.
Antworten
  • method name.
  • return type.
  • number of parameters.
  • order of the parameters.

Frage 16

Frage
All import declarations must be placed
Antworten
  • inside the class declaration’s body.
  • before the class declaration.
  • after the class declaration.
  • all of the above will work.

Frage 17

Frage
The preferred way to traverse a two-dimensional array is to use _______ .
Antworten
  • a do while statement.
  • a for statement.
  • two nested for statements.
  • three nested for statements.

Frage 18

Frage
Which of the following will count down from 10 to 1 correctly?
Antworten
  • 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-- )

Frage 19

Frage
Which of the following does not contribute to improved software reusability?
Antworten
  • 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.

Frage 20

Frage
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(________); } }
Antworten
  • date
  • test.date
  • date.toString()
  • test.date.toString()

Frage 21

Frage
Which of the following is a valid identifier? (Choose all that apply.)
Antworten
  • class
  • radius
  • 9X
  • 8+9
  • $343

Frage 22

Frage
When should a program explicitly use the this reference?
Antworten
  • Accessing a private variable.
  • Accessing a public variable.
  • Accessing a local variable.
  • Accessing a field that is shadowed by a local variable.

Frage 23

Frage
Variables that are shared by every instances of a class are ________.
Antworten
  • class variables
  • public variables
  • private variables
  • instance variables

Frage 24

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

Frage 25

Frage
Which of the following is arranged in increasing size order?
Antworten
  • field, bit, file, record.
  • byte, file, database, record.
  • byte, field, file, record.
  • bit, field, record, file.

Frage 26

Frage
Which method can be used to read a whole line from the file?
Antworten
  • nextInt
  • next
  • nextLine
  • nextDouble

Frage 27

Frage
-24 % -5 is ________.
Antworten
  • 3
  • -3
  • 4
  • -4
  • 0

Frage 28

Frage
Analyze the following code. public class Test { public static void main(String[ ] args) { int month = 09; System.out.println("month is " + month); } }
Antworten
  • 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.

Frage 29

Frage
A decision symbol in an activity diagram takes the shape of a ________.
Antworten
  • Diamond.
  • Rectangle.
  • Circle.
  • Triangle.

Frage 30

Frage
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; } }
Antworten
  • 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

Frage 31

Frage
Which correctly creates an array of five empty Strings?
Antworten
  • String[ ] a = new String [5];
  • String[ ] a = new String [5]; for (int i = 0; i < 5; a[i++] = null);
  • String[ ] a = {"", "", "", "", ""};
  • String[5] a;

Frage 32

Frage
Which of the following are Java keywords?
Antworten
  • instanceof
  • instanceOf
  • casting
  • cast

Frage 33

Frage
When you return an array from a method, the method returns ________.
Antworten
  • a copy of the array
  • the reference of the array
  • a copy of the first element
  • the length of the array

Frage 34

Frage
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"); } }
Antworten
  • s1 and s2 reference to different String objects
  • s1 and s2 reference to the same String object

Frage 35

Frage
Which of the following should usually be private?
Antworten
  • Methods.
  • Constructors.
  • Variables (or fields).
  • All of the above.

Frage 36

Frage
When an argument is passed by reference:
Antworten
  • 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.

Frage 37

Frage
How many times will the following code print "Welcome to Java"? int count = 0; do { System.out.println("Welcome to Java"); } while (count++ < 10);
Antworten
  • 10
  • 8
  • 0
  • 9
  • 11

Frage 38

Frage
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?
Antworten
  • Only TestCircle.java compiles.
  • Both compile fine.
  • Neither compiles successfully.
  • Only Circle.java compiles.

Frage 39

Frage
The default value for data field of a boolean type, numeric type, object type is ________, respectively.
Antworten
  • true, 1, Null
  • true, 1, null
  • false, 0, null
  • false, 1, null
  • true, 0, null

Frage 40

Frage
Which of the following is not a valid Java identifier?
Antworten
  • my Value
  • $_AAA1
  • width
  • m_x

Frage 41

Frage
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
Antworten
  • 0
  • 3
  • 9

Frage 42

Frage
Which of the following is not a superclass/subclass relationship?
Antworten
  • Ford/Taurus.
  • University/Brown University.
  • Sailboat/Tugboat.
  • Country/USA.

Frage 43

Frage
Which of the following is the shape of an action-state symbol?
Antworten
  • Diamond.
  • Circle.
  • Rectangle with left and right sides replaced with arcs curving outward.
  • Rounded rectangle.

Frage 44

Frage
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); } }
Antworten
  • 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.

Frage 45

Frage
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!" );
Antworten
  • This porridge is too hot.
  • This porridge is too cold. This porridge is just right!
  • This porridge is just right!
  • None of the above.

Frage 46

Frage
A method must declare to throw ________.
Antworten
  • Error
  • unchecked exceptions
  • checked exceptions
  • RuntimeException

Frage 47

Frage
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"); } }
Antworten
  • 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.

Frage 48

Frage
Which syntax imports all static members of class Math?
Antworten
  • static import java.lang.Math.*.
  • import static java.lang.Math.*.
  • static import java.lang.Math.
  • import static java.lang.Math.

Frage 49

Frage
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.)
Antworten
  • delete
  • replace
  • append
  • reverse
  • insert

Frage 50

Frage
Every letter in a Java keyword is in lowercase.
Antworten
  • true
  • false

Frage 51

Frage
Math.pow(2, 3) returns ________.
Antworten
  • 8.0
  • 9.0
  • 8
  • 9

Frage 52

Frage
Which of the following classes cannot be extended?
Antworten
  • class A { protected A();}
  • class A { private A();}
  • final class A { }
  • class A { }

Frage 53

Frage
In an expression containing values of the types int and double, the ________ values are ________ to ________ values for use in the expression.
Antworten
  • int, promoted, double.
  • int, demoted, double.
  • double, promoted, int.
  • double, demoted, int.

Frage 54

Frage
Having a this reference allows:
Antworten
  • 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.

Frage 55

Frage
An instance of ________ describes programming errors, such as bad casting, accessing an out-of-bounds array, and numeric errors..
Antworten
  • Exception
  • NumberFormatException
  • Error
  • RuntimeException
  • Throwable

Frage 56

Frage
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; } }
Antworten
  • 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

Frage 57

Frage
How many significant digits does a double variable have?
Antworten
  • 7.
  • 8.
  • 14.
  • 15.

Frage 58

Frage
In Java graphics, coordinate units are measured in ________.
Antworten
  • dots.
  • pixels.
  • points.
  • inches.

Frage 59

Frage
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?
Antworten
  • 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 ++;

Frage 60

Frage
The ________ method returns a raised to the power of b.
Antworten
  • Math.pow(a, b)
  • Math.pow(b, a)
  • Math.power(a, b)
  • Math.exponent(a, b)

Frage 61

Frage
Which of the following will not produce a compiler error?
Antworten
  • 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.

Frage 62

Frage
The default equals implementation determines:
Antworten
  • 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.

Frage 63

Frage
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) { } }
Antworten
  • 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.

Frage 64

Frage
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); } }
Antworten
  • 7654321 1234567
  • 1234567 7654321
  • 7654321 7654321
  • 1234567 1234567

Frage 65

Frage
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)?
Antworten
  • aaaa
  • aaa
  • invalid call
  • aaaaa

Frage 66

Frage
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.
Antworten
  • A and B.
  • A and C.
  • B and C.
  • All.

Frage 67

Frage
In array items, which expression below accesses the value at row 3 and column 4?
Antworten
  • items[ 3 ].[ 4 ].
  • items[ 3[ 4 ] ].
  • items[ 3 ][ 4 ].
  • items[ 3, 4 ].

Frage 68

Frage
Which of the following is the correct statement to return JAVA?
Antworten
  • String.toUpperCase("Java")
  • "Java".toUpperCase()
  • toUpperCase("Java")
  • "Java".toUpperCase("Java")

Frage 69

Frage
Which statement is false?
Antworten
  • 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.

Frage 70

Frage
Which of the following is not an arithmetic operator?
Antworten
  • +
  • -
  • .
  • %

Frage 71

Frage
Which of the following classes is not used for file input?
Antworten
  • FileInputStream
  • FileReader
  • ObjectInputStream
  • Formatter

Frage 72

Frage
Consider the code segment below. if ( gender == 1 ) { if ( age >= 65 ) ++seniorFemales; } // end if This segment is equivalent to which of the following?
Antworten
  • 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;

Frage 73

Frage
A final field should also be declared ________ if it is initialized in its declaration.
Antworten
  • private.
  • public.
  • protected.
  • static.

Frage 74

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

Frage 75

Frage
A default constructor has how many parameters?
Antworten
  • 0.
  • 1.
  • 2.
  • Variable.

Frage 76

Frage
The ________ method immediately terminates the program.
Antworten
  • System.stop(0);
  • System.halt(0);
  • System.terminate(0);
  • System.exit(0);
  • System.quit(0);

Frage 77

Frage
Sentinel-controlled repetition is also known as:
Antworten
  • Definite repetition.
  • Indefinite repetition.
  • Multiple repetition.
  • Double repetition.

Frage 78

Frage
Polymorphism means ________.
Antworten
  • 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

Frage 79

Frage
Which of the following is not a syntax error?
Antworten
  • System.out.println( 'Hello world!' ):
  • System.out.println( "Hello . world!" );
  • System.out.println( "Hello world!" );
  • System.out.println( Hello world! );

Frage 80

Frage
What is k after the following block executes? { int k = 2; nPrint("A message", k); } System.out.println(k);
Antworten
  • 2
  • 1
  • 0
  • k is not defined outside the block. So, the program has a compile error

Frage 81

Frage
The _________ of a class are also called the public services or the public interface that the class provides to its clients.
Antworten
  • public constructors.
  • public instance variables.
  • public methods.
  • All of the above.

Frage 82

Frage
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; } }
Antworten
  • 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());

Frage 83

Frage
What do the following statements do? double[] array; array = new double[ 14 ];
Antworten
  • 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.

Frage 84

Frage
When you invoke a method with a parameter, the value of the argument is passed to the parameter. This is referred to as ________.
Antworten
  • pass by name
  • pass by value
  • pass by reference
  • method invocation

Frage 85

Frage
Which of following is not a correct method in Character? (Choose all that apply.)
Antworten
  • isDigit()
  • toLowerCase(char)
  • isLetter(char)
  • toUpperCase()
  • isLetterOrDigit(char)

Frage 86

Frage
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);
Antworten
  • 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.

Frage 87

Frage
Every class in Java, except ________, extends an existing class.
Antworten
  • Integer.
  • Object.
  • String.
  • Class.

Frage 88

Frage
By default, the classpath consists only of the ________. However, the classpath can be modified by providing the ________ option to the javac compiler.
Antworten
  • root directory of the package, -d.
  • current directory, -d.
  • root directory of the package, -classpath.
  • current directory, -classpath.

Frage 89

Frage
Which of the following is not a compilation error?
Antworten
  • 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.

Frage 90

Frage
________ is a simple but incomplete version of a method.
Antworten
  • A non-main method
  • A method developed using top-down approach
  • A stub
  • A main method

Frage 91

Frage
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] + " "); } }
Antworten
  • Welcome t Java
  • Welc me t Java
  • Welc me to Java
  • Welcome to Java

Frage 92

Frage
Which of the following code segments does not increment val by 3:
Antworten
  • 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.

Frage 93

Frage
The import declaration import *; ________.
Antworten
  • causes a compilation error.
  • imports all classes in the library.
  • imports the default classes in the library.
  • imports the classes in package java.lang.

Frage 94

Frage
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.
Antworten
  • RuntimeException
  • Throwable
  • Error
  • Exception
  • NumberFormatException

Frage 95

Frage
An instance of ________ describes the errors caused by your program and external circumstances. These errors can be caught and handled by your program.
Antworten
  • NumberFormatException
  • Error
  • RuntimeException
  • Throwable
  • Exception

Frage 96

Frage
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;
Antworten
  • 119
  • 51
  • 127
  • 59

Frage 97

Frage
When method printf requires multiple arguments, the arguments are separated with ________.
Antworten
  • colons (:).
  • semicolons (;).
  • commas (,).
  • periods (.).

Frage 98

Frage
Analyze the following statement: double sum = 0; for (double d = 0; d<10;) { d += 0.1; sum += sum + d; }
Antworten
  • 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.

Frage 99

Frage
Suppose x is 1. What is x after x -= 1?
Antworten
  • 0
  • 1
  • 2
  • -1
  • -2

Frage 100

Frage
Stacks are known as ________ data structures.
Antworten
  • FIFO.
  • FILO.
  • LIFO.
  • LILO.

Frage 101

Frage
Which statement is true when a superclass has protected instance variables?
Antworten
  • 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.

Frage 102

Frage
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); } }
Antworten
  • 1.0
  • 2.0
  • 4.0
  • 3.0

Frage 103

Frage
Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following methods will cause the list to become [Beijing, Chicago, Singapore]?
Antworten
  • x.add(2, "Chicago")
  • x.add(1, "Chicago")
  • x.add("Chicago")
  • x.add(0, "Chicago")

Frage 104

Frage
Which of the following statements are true?
Antworten
  • 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.

Frage 105

Frage
The visibility of these modifiers increases in this order:
Antworten
  • 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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