question

The extension name of a Java bytecode file is

answer

.class

question

What are examples of Operating Systems?

answer

Linux, Windows, Mac

question

What are examples of reserved words>

answer

static,public, void, class

question

Java, can run from what Web browser?

answer

applets.

question

Every statement in Java must end with a

answer

semicolon

question

What is an object oriented programming language?

answer

c++, Java, C#

question

Java source code can be executed on a Java virtual Machine

answer

false

question

If a program compiles fine, but it produces an incorrect result then the program suffers,

answer

a logic error.

question

9 Suppose you define a Java class as follows: public class Test { } In order to compile this program, the source code should be stored in a file named

answer

Test.java

question

What method displays a message in a dialog box?

answer

A. JOptionPane.showMessageDialog(null, "Welcome to Java!")? C. JOptionPane.showMessageDialog(null, "Welcome to Java!", "Example 1.2 Output", JOptionPane.INFORMATION_MESSAGE)?

question

How do you correctly display We correctly display, "Welcome to Java!"

answer

B. System.out.print("Welcome to Java")? C. System.out.println("Welcome to Java")?

question

What loads the Java bytecode to the memory?

answer

class loader

question

The JDK command to compile a class in the file Test.java is

answer

javac Test.java

question

Who developed Java

answer

Sun Microsystem

question

Java compiler translates Java source code into

answer

Java bytecode

question

What is Architecture Neutral?

answer

Java

question

Java virtual Machine

answer

is a software that interprets Java bytecode

question

You can use

answer

java, to run a java program

question

A compiler

answer

translates high level language program into machine language program

question

.java

answer

the extension name of a java source code file

question

softwares and programs

answer

are instructions to the computer

question

the speed of the cpu may be measured in

answer

gigahertz/megahertz

question

programming style is important because

answer

good programming makes a program more readable. and a good programming style helps reduce errors.

question

a block is enclosed inside

answer

braces

question

25 To use JOptionPane in your program, you may import it using:

answer

A. import javax.swing.*? D. import javax.swing.JOptionPane?

question

What does line 1 define in a program?

answer

A class, Every Java program must have at least one class. Each class have a name. By convention, class names start with an uppercase letter.

question

What does line 2 define in a program?

answer

The main method. The program is executed from the main method. A class may contain several methods. The main method is the entry point where the program begins execution.

question

What does a method contain?

answer

It is constructed of statements. The main method is this program contains the System.out.println statement. This statement displays the string Welcome to Java! on the console (line4). String is a programming term meaning a sequence of characters/ A string must be enclosed in double quotation marks. Every statement in Java ends with a semicolon; known as a statement terminator.

question

What are reserved words or keywords?

answer

they have a specific meaning to the compiler and cannot be used for other purposes in the program. For example, when the compiler sees the word class, it understands that the word after class is the name fir the class. Other reserved words in this program, are public, static, and void.

question

What is Line 3?

answer

It is a comment that documents what the program is and how it is constructed. Comments help programmers to communicate and understand the program. They are not programming statements and thus are ignored by the compiler. In java, comments are preceeded by 2 //, on a line, called a line comment. or ecnclosed /* and */ on one or several lines, called a block comment or paragraph comment. When the compiler sees //, it ignores all text on the same line. When it sees /*, it scans for the next */ and ignores any text.

question

What do a pair of curly braces form?

answer

The form a block that groups the program's components. In Java, each block begins with a opening brace {, and ends with a closing }, Every class has a class block that groups the data and methods of the class. Similarly every method has a method block that groups the statement in the method. Blocks can be nested, meaning that one block can be placed within another.

question

Syntax errors,

answer

most common error. ( if a semicolon is missing, a brace is missing, a quotation mark is missing, or a word is misspelled) {}- denotes a block to enclose statements ()= used with methods [] denote an array // precede a comment line "" enclose a string ( sequence of characters) ; marks the end of a statement

question

What do you do if your program has run time errors?

answer

you have to modify it, recompile it, and execute it again.You can use any text editor or IDE to create or edit Java source code file.

question

What happens if you do not have any syntax errors?

answer

The compiler generates a bytecode file with a .class extension. This, the preceding commanding generates a file named Welcome.class. Java is translated into byte code and can be executed by any program or machine.

question

The java language

answer

is a high level language, but java bytecode is a low level language. The bytecode is similar to machine instructions, but is architecture neutral and can run on any platform that has Java virtual Machine. Java bytecode can run on a variety of hardware platforms and operating systems. Java source code is compiled into java bytecode and java bytecode is interpreted by JVM.

question

javac

answer

Welcome.java

question

Welcome.class

answer

java command

question

When executing a program,

answer

The java virtual machine first loads the bytecode of the class memory using a program classed the class order. If your pgroam uses other classes, the class loader dynamically loads them just before they are needed. After a class, is loader, the JVM uses a program called the bytecode verifer to check the validity of the bytecode and to ensure that the bytecode does not violate Java's security restrictions. Java enforces strict security to make sure files are not tampered with.

question

To rewrite a text in a message box you use:

answer

The Joption class option! it is one of the many predefine classed in the Java library. you can use this rather than reinvent the wheel.

question

There are two types of block statements

answer

next line style, and end of line style. The next line style aligns the braces vertically and makes programs easy to read, whereas the end of line style saves space, and avoids errors.

question

What are runtime errors

answer

They are errors that cause a program to terminate abnormally. They occur while a program is running in an environment that detects an operation that is impossible to carry out. Input mistakes typically cause runtime errors. An input erros occurs when the program is waiting for the user to enter a value, but the user enters a value that the program cannot handle. For instance, if the program expects to read in a number, but instead the user enters a string, this causes data-type errors.

question

Logic errors

answer

The program does not perform what it is intended to do

question

compile java

answer

javac

question

run java

answer

java command

question

the keyword class introduces, a

answer

class definition, which is included in the block.

question

Main methods are contained in a class.

answer

To run a java program, the program must have a main method. The main method is is the entry point where the program will start execution.

question

Reserved words, or keywords

answer

have a specific meaning to the compiler, and cannot be used for other purposes.

question

specific import

answer

specifies a single class to be imported. Example: import javax.swing.JOptionPane; (Ch. 1 p. 17)

question

wildcard import

answer

imports all classes in a package. Example: import javax.swing.*; (Ch. 1 p. 17)

question

What is the Unicode for the character A is 65. The expression 'A'+1 evaluates to

answer

B. 66

question

5 % 2

answer

1

question

Which of the following is a constant according to Java naming conventions?

answer

COUNT, MAX_VALUE

question

What keyword must be declared to be used as a constant?

answer

final

question

15 % 4 is _____

answer

B. 3

question

What happens if you attempt to add an int, a byte, a long, and a double, the result will be a

answer

double value.

question

public class Test { public static void main(String[] args) { int x = 1? int y = x++ + x? System.out.println("y is " + y)? } }

answer

y is three

question

9 Which of the following assignment statements is incorrect?

answer

A. i == j == k == 1? D. i = 1 = j = 1 = k = 1?

question

What statements are not illegal?

answer

A. short s = 10? C. int t = 23? D. float f = 34?

question

To declare an int variable number with initial value 2, you write

answer

int number=2

question

12 According to Java naming convention, which of the following names can be variables?

answer

C. totalLength A. findArea

question

The assignment operator in Java is

answer

=

question

What value is printed? public static void main(String[] args) { int j = 0? int i = ++j + j * 5? System.out.println("What is i? " + i)? } }

answer

6

question

15 Analyze the following code. import javax.swing.*? public class ShowErrors { public static void main(String[] args) { int i? int j? String s = JOptionPane.showInputDialog(null, "Enter an integer", "Input", JOptionPane.QUESTION_MESSAGE)? j = Integer.parseInt(s)? i = (i + 4)? }

answer

D. The program cannot compile because i does not have an initial value when it is used in i = i + 4?

question

Every letter in Java is lowercase

answer

true

question

a variable may be assignment a value only once in a program

answer

false

question

Which of the following statements are correct?

answer

A. char c = 100? C. char c = 'd'?

question

A java statement ends with a semicolon

answer

true

question

To declare a constant MAX_LENGTH inside a method with value 99.98, you write

answer

C. final double MAX_LENGTH = 99.98?

question

the value of a variable can be changed

answer

true

question

The __________ method displays an input dialog for reading a string.

answer

A. String string = JOptionPane.showInputDialog("Enter a string")? D. String string = JOptionPane.showInputDialog(null, "Enter a string", "Input Demo", JOptionPane.QUESTION_MESSAGE)? E. String string = JOptionPane.showInputDialog(null, "Enter a string")?

question

The following code fragment reads in two numbers: Scanner input = new Scanner(System.in)? int i = input.nextInt()? double d = input.nextDouble()? What are the correct ways to enter these two numbers?

answer

A. Enter an integer, a space, a double value, and then the Enter key. B. Enter an integer, an Enter key, a double value, and then the Enter key. D. Enter an integer, two spaces, a double value, and then the Enter key.

question

25 What is "Welcome" + 1 + 1*2?

answer

D. Welcome12

question

A constant can be defined using using the final keyword.

answer

true

question

Suppose x is a char variable with a value 'b'. What will be displayed by the statement System.out.println(++x)?

answer

c

question

Are the following four statements equivalent? number += 1? number = number + 1? number++? ++number?

answer

yes

question

Which of the following are not valid assignment statements?

answer

55=x;

question

5 Which of the following assignment statements is correct to assign character 5 to c?

answer

B. char c = '5'?

question

You can assign the value in ________ to an int variable.

answer

B. 93 C. 'x'

question

What is x after the following statements? int x = 2? int y = 1? x *= y + 1?

answer

D. x is 4.

question

8 Which of the following are the same as 1545.534?

answer

A. 1545534.0e3 B. 154553.4e2 C. 1.545534e+3 D. 0.1545534e+4

question

The expression 4 + 20 / (3- 1) * 2 is evaluated to

answer

24

question

To declare a constant PI, you write

answer

D. final double PI = 3.14159?

question

The __________ method parses a string s to a double value.

answer

C. Double.parseDouble(s)?

question

12 Which of the following are correct names for variables according to Java naming conventions?

answer

B. radius C. findArea

question

-15 % 4 is _____

answer

D. -3

question

You can cast a character value to an int or an int to a char

answer

true

question

15 A variable may be assigned a value only once in the program.

answer

false

question

17 What is the exact output of the following code? double area = 3.5? System.out.print("area")? System.out.print(area)?

answer

area3.5

question

18 What is the value of (double)5/2?

answer

2.5

question

If you attempt to add an int, a byte, a long, and a double, the result will be a __________ value.

answer

double

Comp Sci Midterm – Flashcards

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards