4184932
Pregunta 1
Pregunta
Which class do you use to write data into a text file?
Respuesta
-
System
-
PrintWriter
-
Scanner
-
File
Pregunta 2
Pregunta
Which of the following statements is false?
Respuesta
-
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.
Pregunta 3
Pregunta
What is the return value of "SELECT".substring(0, 5)?
Respuesta
-
"SELECT"
-
"SELE"
-
"SELEC"
-
"ELECT"
Pregunta 4
Pregunta
Which of the following assignment statements is incorrect? (Choose all that apply.)
Respuesta
-
i == j == k == 1;
-
i = j = k = 1;
-
i = 1; j = 1; k = 1;
-
i = 1 = j = 1 = k = 1;
Pregunta 5
Pregunta
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.
Respuesta
-
square brackets ([]).
-
ellipsis ().
-
varargs keyword.
-
All of the above are acceptable to indicate a variable number of arguments.
Pregunta 6
Pregunta
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?
Respuesta
-
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 } };.
Pregunta 7
Pregunta
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?
Respuesta
-
protected
-
public
-
private
-
Use the default modifier.
Pregunta 8
Pregunta
Which of the following statements are true about an immutable object? (Choose all that apply.)
Respuesta
-
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.
Pregunta 9
Pregunta
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");
}
}
Respuesta
-
s1 and s2 reference to different String objects
-
s1 and s2 reference to the same String object
Pregunta 10
Pregunta
Which of the following is not an algorithm?
Respuesta
-
A recipe.
-
Operating instructions.
-
Textbook index.
-
Shampoo instructions (lather, rinse, repeat).
Pregunta 11
Pregunta
Which of the following segments is a proper way to call the method readData four times?
Respuesta
-
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
Pregunta 12
Pregunta
Which method returns an array of the enum’s constants?
Respuesta
-
values.
-
getValues.
-
constants.
-
getConstants.
Pregunta 13
Pregunta
An anonymous String:
Respuesta
-
has no value.
-
is a string literal.
-
can be changed.
-
none of the above.
Pregunta 14
Pregunta
What exception type does the following program throw?
public class Test {
public static void main(String[ ] args) {
Object o = null;
System.out.println(o);
}
}
Respuesta
-
StringIndexOutOfBoundsException
-
NullPointerException
-
ArrayIndexOutOfBoundsException
-
No exception
-
ArithmeticException
Pregunta 15
Pregunta
Overloaded methods always have the same _________.
Respuesta
-
method name.
-
return type.
-
number of parameters.
-
order of the parameters.
Pregunta 16
Pregunta
All import declarations must be placed
Respuesta
-
inside the class declaration’s body.
-
before the class declaration.
-
after the class declaration.
-
all of the above will work.
Pregunta 17
Pregunta
The preferred way to traverse a two-dimensional array is to use _______ .
Respuesta
-
a do while statement.
-
a for statement.
-
two nested for statements.
-
three nested for statements.
Pregunta 18
Pregunta
Which of the following will count down from 10 to 1 correctly?
Respuesta
-
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-- )
Pregunta 19
Pregunta
Which of the following does not contribute to improved software reusability?
Respuesta
-
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.
Pregunta 20
Pregunta
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(________);
}
}
Respuesta
-
date
-
test.date
-
date.toString()
-
test.date.toString()
Pregunta 21
Pregunta
Which of the following is a valid identifier? (Choose all that apply.)
Respuesta
-
class
-
radius
-
9X
-
8+9
-
$343
Pregunta 22
Pregunta
When should a program explicitly use the this reference?
Respuesta
-
Accessing a private variable.
-
Accessing a public variable.
-
Accessing a local variable.
-
Accessing a field that is shadowed by a local variable.
Pregunta 23
Pregunta
Variables that are shared by every instances of a class are ________.
Respuesta
-
class variables
-
public variables
-
private variables
-
instance variables
Pregunta 24
Pregunta
Which of the following is true? (Choose all that apply.)
Respuesta
-
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.
Pregunta 25
Pregunta
Which of the following is arranged in increasing size order?
Respuesta
-
field, bit, file, record.
-
byte, file, database, record.
-
byte, field, file, record.
-
bit, field, record, file.
Pregunta 26
Pregunta
Which method can be used to read a whole line from the file?
Respuesta
-
nextInt
-
next
-
nextLine
-
nextDouble
Pregunta 27
Pregunta
-24 % -5 is ________.
Respuesta
-
3
-
-3
-
4
-
-4
-
0
Pregunta 28
Pregunta
Analyze the following code.
public class Test {
public static void main(String[ ] args) {
int month = 09;
System.out.println("month is " + month);
}
}
Respuesta
-
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.
Pregunta 29
Pregunta
A decision symbol in an activity diagram takes the shape of a ________.
Respuesta
-
Diamond.
-
Rectangle.
-
Circle.
-
Triangle.
Pregunta 30
Pregunta
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;
}
}
Respuesta
-
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
Pregunta 31
Pregunta
Which correctly creates an array of five empty Strings?
Respuesta
-
String[ ] a = new String [5];
-
String[ ] a = new String [5]; for (int i = 0; i < 5; a[i++] = null);
-
String[ ] a = {"", "", "", "", ""};
-
String[5] a;
Pregunta 32
Pregunta
Which of the following are Java keywords?
Respuesta
-
instanceof
-
instanceOf
-
casting
-
cast
Pregunta 33
Pregunta
When you return an array from a method, the method returns ________.
Respuesta
-
a copy of the array
-
the reference of the array
-
a copy of the first element
-
the length of the array
Pregunta 34
Pregunta
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");
}
}
Respuesta
-
s1 and s2 reference to different String objects
-
s1 and s2 reference to the same String object
Pregunta 35
Pregunta
Which of the following should usually be private?
Respuesta
-
Methods.
-
Constructors.
-
Variables (or fields).
-
All of the above.
Pregunta 36
Pregunta
When an argument is passed by reference:
Respuesta
-
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.
Pregunta 37
Pregunta
How many times will the following code print "Welcome to Java"?
int count = 0;
do {
System.out.println("Welcome to Java");
} while (count++ < 10);
Respuesta
-
10
-
8
-
0
-
9
-
11
Pregunta 38
Pregunta
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?
Respuesta
-
Only TestCircle.java compiles.
-
Both compile fine.
-
Neither compiles successfully.
-
Only Circle.java compiles.
Pregunta 39
Pregunta
The default value for data field of a boolean type, numeric type, object type is ________, respectively.
Respuesta
-
true, 1, Null
-
true, 1, null
-
false, 0, null
-
false, 1, null
-
true, 0, null
Pregunta 40
Pregunta
Which of the following is not a valid Java identifier?
Respuesta
-
my Value
-
$_AAA1
-
width
-
m_x
Pregunta 41
Pregunta
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
Respuesta
-
0
-
3
-
9
Pregunta 42
Pregunta
Which of the following is not a superclass/subclass relationship?
Respuesta
-
Ford/Taurus.
-
University/Brown University.
-
Sailboat/Tugboat.
-
Country/USA.
Pregunta 43
Pregunta
Which of the following is the shape of an action-state symbol?
Respuesta
-
Diamond.
-
Circle.
-
Rectangle with left and right sides replaced with arcs curving outward.
-
Rounded rectangle.
Pregunta 44
Pregunta
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);
}
}
Respuesta
-
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.
Pregunta 45
Pregunta
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!" );
Respuesta
-
This porridge is too hot.
-
This porridge is too cold. This porridge is just right!
-
This porridge is just right!
-
None of the above.
Pregunta 46
Pregunta
A method must declare to throw ________.
Respuesta
-
Error
-
unchecked exceptions
-
checked exceptions
-
RuntimeException
Pregunta 47
Pregunta
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");
}
}
Respuesta
-
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.
Pregunta 48
Pregunta
Which syntax imports all static members of class Math?
Respuesta
-
static import java.lang.Math.*.
-
import static java.lang.Math.*.
-
static import java.lang.Math.
-
import static java.lang.Math.
Pregunta 49
Pregunta
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.)
Respuesta
-
delete
-
replace
-
append
-
reverse
-
insert
Pregunta 50
Pregunta
Every letter in a Java keyword is in lowercase.
Respuesta
-
true
-
false
Pregunta 51
Pregunta
Math.pow(2, 3) returns ________.
Respuesta
-
8.0
-
9.0
-
8
-
9
Pregunta 52
Pregunta
Which of the following classes cannot be extended?
Respuesta
-
class A { protected A();}
-
class A { private A();}
-
final class A { }
-
class A { }
Pregunta 53
Pregunta
In an expression containing values of the types int and double, the ________ values are ________ to ________ values for use in the expression.
Respuesta
-
int, promoted, double.
-
int, demoted, double.
-
double, promoted, int.
-
double, demoted, int.
Pregunta 54
Pregunta
Having a this reference allows:
Respuesta
-
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.
Pregunta 55
Pregunta
An instance of ________ describes programming errors, such as bad casting, accessing an out-of-bounds array, and numeric errors..
Respuesta
-
Exception
-
NumberFormatException
-
Error
-
RuntimeException
-
Throwable
Pregunta 56
Pregunta
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;
}
}
Respuesta
-
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
Pregunta 57
Pregunta
How many significant digits does a double variable have?
Respuesta
-
7.
-
8.
-
14.
-
15.
Pregunta 58
Pregunta
In Java graphics, coordinate units are measured in ________.
Respuesta
-
dots.
-
pixels.
-
points.
-
inches.
Pregunta 59
Pregunta
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?
Respuesta
-
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 ++;
Pregunta 60
Pregunta
The ________ method returns a raised to the power of b.
Respuesta
-
Math.pow(a, b)
-
Math.pow(b, a)
-
Math.power(a, b)
-
Math.exponent(a, b)
Pregunta 61
Pregunta
Which of the following will not produce a compiler error?
Respuesta
-
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.
Pregunta 62
Pregunta
The default equals implementation determines:
Respuesta
-
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.
Pregunta 63
Pregunta
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) {
}
}
Respuesta
-
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.
Pregunta 64
Pregunta
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);
}
}
Respuesta
-
7654321 1234567
-
1234567 7654321
-
7654321 7654321
-
1234567 1234567
Pregunta 65
Pregunta
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)?
Respuesta
-
aaaa
-
aaa
-
invalid call
-
aaaaa
Pregunta 66
Pregunta
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.
Respuesta
-
A and B.
-
A and C.
-
B and C.
-
All.
Pregunta 67
Pregunta
In array items, which expression below accesses the value at row 3 and column 4?
Respuesta
-
items[ 3 ].[ 4 ].
-
items[ 3[ 4 ] ].
-
items[ 3 ][ 4 ].
-
items[ 3, 4 ].
Pregunta 68
Pregunta
Which of the following is the correct statement to return JAVA?
Respuesta
-
String.toUpperCase("Java")
-
"Java".toUpperCase()
-
toUpperCase("Java")
-
"Java".toUpperCase("Java")
Pregunta 69
Pregunta
Which statement is false?
Respuesta
-
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.
Pregunta 70
Pregunta
Which of the following is not an arithmetic operator?
Respuesta
-
+
-
-
-
.
-
%
Pregunta 71
Pregunta
Which of the following classes is not used for file input?
Respuesta
-
FileInputStream
-
FileReader
-
ObjectInputStream
-
Formatter
Pregunta 72
Pregunta
Consider the code segment below.
if ( gender == 1 )
{
if ( age >= 65 )
++seniorFemales;
} // end if
This segment is equivalent to which of the following?
Respuesta
-
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;
Pregunta 73
Pregunta
A final field should also be declared ________ if it is initialized in its declaration.
Respuesta
-
private.
-
public.
-
protected.
-
static.
Pregunta 74
Pregunta
The ________ method displays an input dialog for reading a string. (Choose all that apply.)
Respuesta
-
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);
Pregunta 75
Pregunta
A default constructor has how many parameters?
Respuesta
-
0.
-
1.
-
2.
-
Variable.
Pregunta 76
Pregunta
The ________ method immediately terminates the program.
Respuesta
-
System.stop(0);
-
System.halt(0);
-
System.terminate(0);
-
System.exit(0);
-
System.quit(0);
Pregunta 77
Pregunta
Sentinel-controlled repetition is also known as:
Respuesta
-
Definite repetition.
-
Indefinite repetition.
-
Multiple repetition.
-
Double repetition.
Pregunta 78
Pregunta
Polymorphism means ________.
Respuesta
-
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
Pregunta 79
Pregunta
Which of the following is not a syntax error?
Respuesta
-
System.out.println( 'Hello world!' ):
-
System.out.println( "Hello . world!" );
-
System.out.println( "Hello world!" );
-
System.out.println( Hello world! );
Pregunta 80
Pregunta
What is k after the following block executes?
{
int k = 2;
nPrint("A message", k);
}
System.out.println(k);
Respuesta
-
2
-
1
-
0
-
k is not defined outside the block. So, the program has a compile error
Pregunta 81
Pregunta
The _________ of a class are also called the public services or the public interface that the class provides to its clients.
Respuesta
-
public constructors.
-
public instance variables.
-
public methods.
-
All of the above.
Pregunta 82
Pregunta
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;
}
}
Respuesta
-
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());
Pregunta 83
Pregunta
What do the following statements do?
double[] array;
array = new double[ 14 ];
Respuesta
-
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.
Pregunta 84
Pregunta
When you invoke a method with a parameter, the value of the argument is passed to the parameter. This is referred to as ________.
Respuesta
-
pass by name
-
pass by value
-
pass by reference
-
method invocation
Pregunta 85
Pregunta
Which of following is not a correct method in Character? (Choose all that apply.)
Respuesta
-
isDigit()
-
toLowerCase(char)
-
isLetter(char)
-
toUpperCase()
-
isLetterOrDigit(char)
Pregunta 86
Pregunta
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);
Respuesta
-
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.
Pregunta 87
Pregunta
Every class in Java, except ________, extends an existing class.
Respuesta
-
Integer.
-
Object.
-
String.
-
Class.
Pregunta 88
Pregunta
By default, the classpath consists only of the ________. However, the classpath can be modified by providing the ________ option to the javac compiler.
Respuesta
-
root directory of the package, -d.
-
current directory, -d.
-
root directory of the package, -classpath.
-
current directory, -classpath.
Pregunta 89
Pregunta
Which of the following is not a compilation error?
Respuesta
-
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.
Pregunta 90
Pregunta
________ is a simple but incomplete version of a method.
Respuesta
-
A non-main method
-
A method developed using top-down approach
-
A stub
-
A main method
Pregunta 91
Pregunta
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] + " ");
}
}
Respuesta
-
Welcome t Java
-
Welc me t Java
-
Welc me to Java
-
Welcome to Java
Pregunta 92
Pregunta
Which of the following code segments does not increment val by 3:
Respuesta
-
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.
Pregunta 93
Pregunta
The import declaration import *; ________.
Respuesta
-
causes a compilation error.
-
imports all classes in the library.
-
imports the default classes in the library.
-
imports the classes in package java.lang.
Pregunta 94
Pregunta
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.
Respuesta
-
RuntimeException
-
Throwable
-
Error
-
Exception
-
NumberFormatException
Pregunta 95
Pregunta
An instance of ________ describes the errors caused by your program and external circumstances. These errors can be caught and handled by your program.
Respuesta
-
NumberFormatException
-
Error
-
RuntimeException
-
Throwable
-
Exception
Pregunta 96
Pregunta
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;
Respuesta
-
119
-
51
-
127
-
59
Pregunta 97
Pregunta
When method printf requires multiple arguments, the arguments are separated with ________.
Respuesta
-
colons (:).
-
semicolons (;).
-
commas (,).
-
periods (.).
Pregunta 98
Pregunta
Analyze the following statement:
double sum = 0;
for (double d = 0; d<10;) {
d += 0.1;
sum += sum + d;
}
Respuesta
-
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.
Pregunta 99
Pregunta
Suppose x is 1. What is x after x -= 1?
Respuesta
-
0
-
1
-
2
-
-1
-
-2
Pregunta 100
Pregunta
Stacks are known as ________ data structures.
Respuesta
-
FIFO.
-
FILO.
-
LIFO.
-
LILO.
Pregunta 101
Pregunta
Which statement is true when a superclass has protected instance variables?
Respuesta
-
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.
Pregunta 102
Pregunta
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);
}
}
Respuesta
-
1.0
-
2.0
-
4.0
-
3.0
Pregunta 103
Pregunta
Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following methods will cause the list to become [Beijing, Chicago, Singapore]?
Respuesta
-
x.add(2, "Chicago")
-
x.add(1, "Chicago")
-
x.add("Chicago")
-
x.add(0, "Chicago")
Pregunta 104
Pregunta
Which of the following statements are true?
Respuesta
-
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.
Pregunta 105
Pregunta
The visibility of these modifiers increases in this order:
Respuesta
-
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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