Chp 2 Flashcards

1
Q

A JAVA APPLICATION

A

Executes when you use teh java command to launch JVM

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2
Q

A COMMENT LINE BEGINS WITH…

A

//

Which is an end-of-line comment

*It terminates at the end of the line on which it appears

** JAVA WILL NOT READ THESE COMMENTS

Example:

// empty statement

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3
Q

TRADITIONAL COMMENTS

PG. 39

A

CAN SPREAD OVER SEVERAL LINES AND ARE DELIMITED BY /* AND */

THESE COMMENTS ARE NOT READ BY JAVA EITHER

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4
Q

JAVADOC

COMMENTS

PG. 39

A

DELIMITED BY /** AND */

ENABLE YOU TO EMBED PROGRAM DOCUMENTATION IN YOUR CODE.

GENTERATES HTML PAGES BASED ON THESE COMMENTS

COMPILER INGNORES ALL TEXT BETWEEN DELIMITERS

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5
Q

SYNTAX ERROR

PG. 39

A

AKA COMPILER ERROR, COMPILE TIME ERROR, COMPILATION ERROR

OCCURS WHEN THE COMPILER ENCOUNTERS CODE THAT VIOLATES JAVA’S LANGUAGE RULES

SIMILAR TO A GRAMMER ERROR IN NATURAL LANGUAGE

THE COMPILER RESPONDS BY ISSUING AN ERROR AND PREVENTING YOUR PROGRAM FROM COMPILING

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6
Q

BLANK LINES

SPACE CHARACTERS

TAB CHARACTERS

PG. 39

A

KNOWN AS WHITE SPACE

WHITE SPACE MAKES PROGRAMS EAISER TO READ AND IS IGNORED BY THE COMPILER

** IN A PROGRAM IT WOULD JUST BE A SKIPPED LINE

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7
Q

KEYWORDS

PG. 40

A

RESERVED FOR USE BY JAVA AND ARE ALWAYS SPELLED WITH ALL LOWERCASE LETTERS

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8
Q

KEYWORD CLASS

PG 40

A

INTRODUCES A CLASS DECLARATION

EX:

public class Welcome1

  • public class being the keyword class*
  • Welcome1 being the class name*
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9
Q

CLASS NAMES

A

BY CONVENTION ALL CLASS NAMES IN JAVA BEGIN WITH A CAPITAL LETTER AND CAPITALIZE THE FIRST LETTER OF EACH WORD THEY INCLUDE

E.G.

SampleClassName

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10
Q

JAVA CLASS NAME

A
  • SERIES OF CHARACTERS CONSISTING OF LETTERS, DIGITS, UNDERSCORES (_) AND DOLLAR SIGNS ($)
  • DOES NOT BEGIN WITH A DIGIT AND DOES NOT CONTAIN SPACES
  • JavaClassNameSample
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11
Q

IS JAVA CASE SENSITIVE?

A
  • YES
  • UPPER AND LOWERCASE LETTERS ARE DISTINCT
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12
Q

THE BODY OF EVERY CLASS DECLARATION

PG. 40

A
  • IS DELIMITED BY BRACES
  • { AND }
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13
Q

A PUBLIC CLASS DECLARATION MUST BE SAVED IN….

A
  • A FILE WITH THE SAME NAME AS THE CLASS FOLLOWED BY THE “.java” FILE NAME EXTENSION
  • E.G public class Welcome1, would be saved as Welcome1.java
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14
Q

METHOD MAIN

PG.41

A
  • STARTING POINT OF EVERY JAVA APPLICATION
  • MUST BEGIN WITH public static void main( String [] args)
  • otherwise the JVM will not execute

Ex:

{

// main method begins execution of java application

public static main void main ( String [] args )

}

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15
Q

METHODS

PG.41

A
  • PERFORM TASKS AND RETURN INFO WHEN THEY COMPLETE THEM
  • KEYWORD void, INDICATES THAT A METHOD WILL PERFORM A TASK BUT RETURN NO INFORMATION

public static void main ( String [] args )

*The parentheses after the identtifirer main indicate that its’s a program building block called method.

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16
Q

STATEMENTS

A
  • INSTRUCT THE COMPUTER TO PERFORM ACTIONS
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17
Q

A STRING

PG.41

A
  • IN DOUBLE QUOTES
  • CALLED A CHARACTER STRING OR STRING LITERAL
  • CAN NOT SPAN MULTIPLE LINES OF CODE

EX:

System.out.println( ” Welcome to Java Programming!” )

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18
Q

STANDARD OUTPUT OBJECT

PG.41

A
  • DISPLAYS CHARACTERS IN THE COMMAND WINDOW
  • System.out
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19
Q

Method

System.out.println

A
  • DISPLAYS THE ARGUMENT IN THE COMMAND WINDOW FOLLOWED BY A NEW LINE CHARACTER TO POSITION THE OUTPUT CURSOR TO THE BEGINING OF THE NEXT LINE
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20
Q

TO COMPILE A PROGRAM

A
  • YOU COMPILE A PROGRAM WITH THE COMMAND javac.
  • IF THE PROGRAM CONTAINS NO SYTAX ERRORS, A CLASS FILE CONTAINING JAVA BYTECODES THAT REPRESENT THE APPLICATION CREATED.
  • THE BYTECODES ARE INTERPRETED BY THE JVM WHEN YOU EXECUTE THE PROGRAM
  1. Open Command Window
  2. Change directory where program is stored using command cd to change directory
  3. once directory is found type javac ClasName.java
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21
Q

TO RUN AN APPLICATION

A
  • TYPE JAVAc
  • FOLLOWED BY THE NAME OF THE CLASS THAT CONTAINS MAIN
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22
Q

System.out.print

not

System.out.println

pg.44

A
  • DISPLAYS ITS ARGUMENT AND POSITIONS THE OUTPUT CURSOR IMMEDIATELY AFTER THE LAST CHARACTER DISPLAYED
  • println vs print (println positions at the next line)
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23
Q

BACKLASH

( \ )

PG.45

A
  • A BACKLASH IN A STRING IS AN ESCAPE CHARACTER
  • JAVA COMBINES IT WITH THE NEXT CHARACTER TO FORM AN ESCAPE SEQUENCE
  • THE ESCAPE SEQUENCE \n represents the newline character

Ex:

{

public static void main ( String [] args)

{

    System.out.println ( "Welcome **\n** to **\n** Java **\n**      Programing!" );

 }

}

Will Display on seperate lines

Welcome to java progaming!

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24
Q

System.out.printf

Method

pg.46

A
  • Syestem.out.printf
  • MEANS “FORMATTED”
  • DISPLAYS FORMATTED DATA
  • FIRST ARGUMENT IS A FORMAT STRING CONTAINING FIXED TEXT AND / OR FORMAT SPECIFIERS
  • EACH FORMAT SPECIFIER INDICATES THE TYPE OF DATA TO OUTPUT AND IS PLACE HOLDERFOR A CORRESPONDING ARGUMENT THAT APPEARS AFTER THE FORMAT STRING
25
**FORMAT SPECIFIERS**
* BEGIN WITH **%** ADN FOLLOWED BY A CHARACTER THAT REPRESENTS THE DATY TYPE * THE FORMAT SPECIFER **%** IS A PLACE HOLDER FOR A STRING
26
**DISPLAYING MULTIPLE LINES WITH** **System.out.printf**
{ System.out.printf( "**%**s \ n**%**s \ n", "Welcome to", "Java Programing!" ); } \* Will Display **Welcome to Java Programing!**
27
**PACKAGES** **PG.48**
* NAMED GROUPS OF RELATED CLASSES * COLLECTIVELY REFFERED TO AS THE ***JAVA CLASS LIBRARY*** OR ***JAVA APPLICATION PROGRAMING INTERFACE*** * ***PREDEFINED CLASSES*** THAT YOU CAN REUSE
28
**IMPORT DECLARATION** **PG 48**
* HELPS THE COMPILER LOCATE CLASS THAT'S USED IN A PROGRAM USUALLY AT BEGINGING AFTER TITLE **import** java.util.Scanner; // program uses Class Scanner
29
**VARIABLE**
* IS A LOCATION IN THE COMPUTERS MEMORY WHERE A VALUE CAN BE STORED FOR USE LATER IN A PROGRAM. ALL VARIABLES MUST BE DECLARED WITH A *_NAME AND TYPE_* BEFORE THEY CAN BE USED **VARIABLE DECLARATION STATEMENT: ** Scanner input = new Scanner ( System.in ); * The **=** indicates that the Scanner variable input should be ***inititalized*** * Variables should be initialized to prepare for use
30
**VARIABLE NAMES** **PG. 52**
CORRESPOND TO LOCATIONS IN THE COMPUTERS MEMORY. EVERY VARIABLE HAS THE NAME, A TYPE, A SIZE, AND A VALUE. A VALUE THAT'S PLACED IN A MEMORY LOCATION REPLACES THE LOCATIONS PERVIOUS VALUE, WHICH IS LOST.
31
**ARITHMETIC OPERATORS** **PG. 53**
* **+** FOR ADDITION * ** -** FOR SUBTRACTION * **\*** FOR MULTIPLICATION * **/** FOR DIVISION * **%** FOR REMAINDER
32
**INTEGER DIVISION** **PG 53**
* YIELDS AN INTERGER QUOTIENT * 7 **/** 4 evaluates to 1 * 17 **/** 5 evaluates to 3 * no rounding occurs **%** yeilds the remainder 7 % 4 yields 3 17 % 5 yields 2
33
**ARITHMETIC EXPRESSIONS**
* MUST BE WRITTEN IN STRAIGHT LINE FORM * EX: A OVER B must be written **a / b**
34
***IF AN EXPRESSION CONTAINS NESTED PARENTHESES (A + B) \* 2***
* THE INTERMOST SET IS EVALUATED FIRST
35
**RULES OF OPERATOR PRECEDENCE**
1. MULTIPLICATION, DIVISION, AND REMAINDER OPERATIONS ARE APPLIED FIRST 2. ADDITION AND SUBTRACTION OPERATORS APPLIED NEXT WHEN WE SAY THE OPERATORS ARE APPLIED FROM LEFT TO RIGHT, WE'RE REFFERING TO THEIR ***ASSOCIATIVITY***. SOME OPERATORS ASSOCIATE FROM RIGHT TO LEFT
36
REDUNDANT PARENTHESES
CAN MAKE AN EXPRESSION CLEARER
37
**THE "IF" STATEMENT** **PG.56**
* MAKES A DECISION BASED ON A CONDITIONS VALUE ( TRUE OR FALSE)
38
EQUALITY OPERATORS
* ** (X == Y)** x is equal to y * **( x != y )** x is not equal to y
39
**RELATIONAL OPERATORS**
* ( X \> Y ) x is greater than y * ( x \< y ) x is less than y * ( x \>= y ) x is greater than or equal to y * ( x \<= y ) x is less or equal to y
40
**EMPTY STATEMENT**
IS A STATEMENT THAT DOES NOT PERFORM A TASK
41
**A ______ BEGINS THE BODY OF EVERY METHOD, AND A _______ ENDS THE BODY OF EVERY METHOD**
LEFT BRACE **{** & RIGHT BRACE **}**
42
**THE ________ STATEMENT IS USED TO MAKE DECISIONS**
***IF STATEMENT***
43
**\_\_\_\_\_\_\_ BEGINS AN END-OF-LINE COMMENT**
**//**
44
\_\_\_\_\_\_, \_\_\_\_\_, AND ______ ARE CALLED WHITE SPACE
***SPACE CHARACTERS*** ***NEW LINES*** ***TABS***
45
\_\_\_\_\_\_ ARE RESERVED FOR JAVA USE
***KEY WORDS***
46
JAVA APPLICATIONS BEGIN EXECUTION AT METHOD \_\_\_\_\_\_\_\_
***METHOD MAIN***
47
METHODS \_\_\_\_\_, \_\_\_\_\_\_, \_\_\_\_\_\_, DISPLAY INFO IN A COMMAND WINDOW
***System.out.print*** ***System.out.println*** ***System.out.printf***
48
COMMENTS CAUSE THE COMPUTER TO PRINT THE TEXT **AFTER THE //** ON THE SCREEN WHEN THE PROGRAM EXECUTES ***TRUE OR FALSE***
***FALSE*** COMMENTS DO NOT CAUSE ANY ACTION TO BE PERFORMED WHEN THE PROGRAM EXECUTES. THEY ARE USED TO DOCUMENT PROGRAMS AND IMPROVE THE READIBILITY
49
**ALL** VARIABLES **MUST** BE GIVEN A TYPE WHEN THEY ARE DECLARED.... TRUE OR FALSE
***TRUE***
50
JAVA CONSIDERS THE VARIABLES **NUMBER** AND **NuMber** TO BE IDENTICAL TRUE OR FALSE
***FALSE*** JAVA IS CASE SENSITIVE SO THESE VAIRABLES ARE DISTINCT
51
THE REMAINDER OPERATOR ( % ) CAN BE USED ONLY WITH INTERGER OPERANDS
***FALSE*** THE REMAINDER OPERATOR CAN ALSO BE USED WITH NONINTERGER OPERANDS IN JAVA
52
THE ARITHMETIC OPERATORS **\* / % + AND -** ALL HAVE THE SAME LEVEL OF PRECEDENCE
***FALSE*** THE OPERATORS **\* AND / AND %** ARE HIGHER THAN OPERATORS **+ AND -**
53
**DECLARE VARIABLES** C, thisIsAVariable, q76354 and number TO BE OF TYPE INT.
**int c, thisIsAVariable, q76356, number;**
54
**PROMPT** **THE *USER* TO ENTER AN INTEGER**
**System.out.print ( "Enter an integer" ) ;**
55
**INPUT AN INTEGER AND ASSIGN THE RESULTS TO INT VARIABLE VALUE.** **ASSUME SCANNER VARIABLE INPUT CAN BE USED TO READ A VALUE FROM THE KEYBOARD**
**value = input.nextInt();**
56
**PRINT "THIS IS A JAVA PROGRAM"** **ON ONE LINE IN THE COMMAND WINDOW.** **USE METHOD *System.out.println***
**System.out.println ( "This is a Java Program!" ) ;**
57
**PRINT** **"THIS IS A JAVA PROGRAM"** **ON 2 LINES IN COMMAND WINDOW** **FISRT LINE SHOULD END WITH JAVA** **USE METHOD *System.out.println***
**System.out.println ( "This is a Java \n Program" ) ;**
58
**PRINT** **"THIS A JAVA PROGRAM"** **ON TWO LINES FIRST LINE ENDING WITH JAVA** **USE METHOD *System.out.printf & two %s format specifiers***
**System.out.printf ( "%s \ n%s \ n", "this is a java", "program" ) ;**
59
**IF THE VARIABLE NUMBER IS NOT EQUAL TO 7, DISPLAY "THE VARIABLE NUMBER IS NOT EQUAL TO 7"**