Java Practice 3

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

Which of the following statements is false?

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

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.

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?

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?

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");
}
}

Which of the following is not an algorithm?

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

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

An anonymous String:

What exception type does the following program throw?

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

Overloaded methods always have the same _________.

All import declarations must be placed

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

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

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

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(________);
}
}

When should a program explicitly use the this reference?

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

Which of the following is arranged in increasing size order?

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

-24 % -5 is ________.

Analyze the following code.

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

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

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;
}
}

Which correctly creates an array of five empty Strings?

Which of the following are Java keywords?

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

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");
}
}

Which of the following should usually be private?

When an argument is passed by reference:

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

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

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?

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

Which of the following is not a valid Java identifier?

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

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

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

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);
}
}

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!" );

A method must declare to throw ________.

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");
}
}

Which syntax imports all static members of class Math?

Every letter in a Java keyword is in lowercase.

Math.pow(2, 3) returns ________.

Which of the following classes cannot be extended?

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

Having a this reference allows:

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

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;
}
}

How many significant digits does a double variable have?

In Java graphics, coordinate units are measured in ________.

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?

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

Which of the following will not produce a compiler error?

The default equals implementation determines:

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) {
}
}

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);
}
}

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)?

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.

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

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

Which statement is false?

Which of the following is not an arithmetic operator?

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

Consider the code segment below.

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

This segment is equivalent to which of the following?

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

A default constructor has how many parameters?

The ________ method immediately terminates the program.

Sentinel-controlled repetition is also known as:

Polymorphism means ________.

Which of the following is not a syntax error?

What is k after the following block executes?

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

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

What do the following statements do?

double[] array;

array = new double[ 14 ];

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

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);

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

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

Which of the following is not a compilation error?

________ is a simple but incomplete version of a method.

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] + " ");
}
}

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

The import declaration import *; ________.

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.

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

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;

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

Analyze the following statement:

double sum = 0;

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

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

Stacks are known as ________ data structures.

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

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);
}
}

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

Which of the following statements are true?

The visibility of these modifiers increases in this order: