Scjp 5 Study Guide Ch. 6

Front 1

String objects are ___, and String reference variables are not

Back 1

immutable

Front 2

if you create a new String without assigning it

Back 2

it will be lost to your program

Front 3

if you redirect a String reference to a new String

Back 3

the old String can be lost

Front 4

String methods use zero-based indexes, except for the

Back 4

second argument of substring()

Front 5

the String class is ___ - its methods can't be overridden

Back 5

final

Front 6

when the JVM finds a String literal, it is added to the

Back 6

String literal pool

Front 7

Strings have a method: length(); arrays have

Back 7

an attribute named length

Front 8

the StringBuffer's API is the same as the new StringBuilder's API, except that

Back 8

StringBuilder's methods are not synchronized for thread safety

Front 9

StringBuilder methods should ___ ___ then StringBuffer methods

Back 9

run faster

Front 10

All of the following apply to both StringBuffer and StringBuilder

Back 10

they are mutable - they can change without creating a new object
StringBuffer methods act on the invoking object, and objects can change without an explicit assignment in the statement
StringBuffer equals() is not overridden; it doesn't compare values

Front 11

remember that chained methods are evaluated from ___ to ___

Back 11

left to right

Front 12

String methods to remember:

Back 12

charAt(), concat(), equalsIgnoreCase(), length(), replace(), substring(), toLowerCase(), toString(), toUpperCase(), and trim()

Front 13

StringBuffer methods to remember:

Back 13

append(), delete(), insert(), reverse(), and toString()

Front 14

the classes you need to understand in java.io are

Back 14

File, FileReader, BufferedReader, FileWriter, BufferedWriter, and PrintWriter

Front 15

a new File object doesn't mean

Back 15

there's a new file on your hard drive

Front 16

File objects can represent either

Back 16

a file or a directory

Front 17

the ___ class lets you manage (add, rename, and delete) files and directories

Back 17

File

Front 18

the methods ___ and ___ add entries to your file system

Back 18

createNewFile() and mkDir()

Front 19

___ and ___ are low-level I/O classes. you can use them to write and read files, but they should usually be wrapped

Back 19

FileWriter and FileReader

Front 20

classes in java.io are designed to be ___ or ___. this is a common use of the decorator design pattern

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"chained" or "wrapped"

Front 21

it's very common to "wrap" a BufferedReader around a ___ to get access to higher-level, more convenient methods

Back 21

FileReader

Front 22

it's very common to "wrap" a BufferedWriter around a ___ to get access to higher-level, more convenient methods

Back 22

FileWriter

Front 23

PrintWriters can be used to wrap other Writers, but as of Java 5 they can be built directly from

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Files or Strings

Front 24

Java 5 PrintWriters have new ___ methods

Back 24

append(), format(), and printf()

Front 25

the classes you need to understand are all in the java.io package; they include:

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ObjectOutputStream and ObjectInputStream primarily, and FileOutputStream and FileInputStream because you will use them to create the low-level streams that the ObjectXxxStream classes will use

Front 26

a class must implement the ___ interface before its objects can be serialized

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Serializable

Front 27

the ___ method serializes objects, and the ___ method deserializes objects

Back 27

ObjectOutputStream.writeObject(), ObjectInputStream.readObject()

Front 28

if you mark an instance variable ___, it will not be serialized even though the rest of the object's state will be

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transient

Front 29

you can supplement a class's automatic serialization process by implementing the ___ and ___ methods. if you do this, embedding calls to defaultWriteObject() and defaultReadObject(), respectively, will handle the part of serialization that happens normally

Back 29

writeObject() and readObject()

Front 30

if a superclass implements Serializable, then its subclasses

Back 30

do automatically

Front 31

if a superclass doesn't implement Serializable, then when a subclass object is deserialized

Back 31

the superclass constructor will run

Front 32

the classes you need to understand are

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java.util.Date, java.util.Calendar, java.text.DateFormat, java.text.NumberFormat, and java.util.Locale

Front 33

most of the Date class's methods have been

Back 33

deprecated

Front 34

a Date is stored as a

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long, the number of milliseconds since January 1, 1970

Front 35

Date objects are go-betweens for the

Back 35

Calendar and Locale classes

Front 36

the ___ provides a powerful set of methods to manipulate dates, performing tasks such as getting days of the week, or adding some number of months or years (or other increments) to a date

Back 36

Calendar

Front 37

create Calendar instances using

Back 37

static factory methods (getInstance())

Front 38

the Calendar methods you should understand are

Back 38

add(), which allows you to add or substract various pieces (minutes, days, years, and so on) of dates, and roll(), which works like add() but doesn't increment a date's bigger pieces. (for example: adding 10 months to an October date changes the month to August, but doesn't increment the Calendar's year value)

Front 39

DateFormat instances are created using static factory methods ___

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getInstance() and getDateInstance()

Front 40

There are several format ___ available in the DateFormat class

Back 40

"styles"

Front 41

___ ___ can be applied against various Locales to create a wide
array of outputs for any given date

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DateFormat styles

Front 42

The ___ method is used to create Strings containing
properly formatted dates

Back 42

DateFormat.format()

Front 43

The ___ class is used in conjunction with DateFormat and NumberFormat

Back 43

Locale

Front 44

Both DateFormat and NumberFormat objects can be constructed with a
specific, immutable ___

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Locale

Front 45

For the exam

Back 45

you should understand creating Locales using language, or a
combination of language and country

Front 46

regex is short for regular expressions, which are the

Back 46

patterns used to search for
data within large data sources

Front 47

regex is a ___ that exists in Java and other languages (such as Perl)

Back 47

sub-language

Front 48

regex lets you create search patterns using literal characters or
___. They allow you to search for slightly more abstract
data like "digits" or "whitespace"

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metacharacters

Front 49

Study the

Back 49

\d, \s, \w, and . metacharacters

Front 50

regex provides for ___ which allow you to specify concepts like: "look
for one or more digits in a row."

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quantifiers

Front 51

Study the

Back 51

?, *, and + greedy quantifiers

Front 52

Remember that metacharacters and Strings don't mix well unless you
remember to

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"escape" them properly. For instance String s = "\\d";

Front 53

The ___ and ___ classes have Java's most powerful regex capabilities

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Pattern and Matcher

Front 54

You should understand the

Back 54

Pattern compile() method and the Matcher
matcher(), pattern(), find(), start(), and group() methods

Front 55

You WON'T need to understand

Back 55

Matcher's replacement-oriented methods

Front 56

You can use java.util.Scanner to do simple regex searches, but it is primarily
intended for ___

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tokenizing

Front 57

___ is the process of splitting delimited data into small pieces

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Tokenizing

Front 58

In tokenizing, the data you want is called ___, and the strings that separate
the tokens are called ___

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tokens, delimiters

Front 59

Tokenizing can be done with the

Back 59

Scanner class, or with String.split()

Front 60

___ are single characters like commas, or complex regex expressions

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Delimiters

Front 61

The ___ class allows you to tokenize data from within a loop, which
allows you to stop whenever you want to

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Scanner

Front 62

The Scanner class allows you to ___ Strings or streams or files

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tokenize

Front 63

The ___ method tokenizes the entire source data all at once, so
large amounts of data can be quite slow to process

Back 63

String.split()

Front 64

New to Java 5 are two methods used to format data for output. These
methods are ___

Back 64

format() and printf(). These methods are found in the
PrintStream class, an instance of which is the out in System.out

Front 65

The format() and printf() methods have ___

Back 65

identical functionality

Front 66

Formatting data with printf() (or format()) is accomplished using

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formatting strings that are associated with primitive or string arguments

Front 67

The format() method allows you to mix

Back 67

literals in with your format strings

Front 68

The format string values you should know are

Back 68

Flags: -, +, 0, "," , and (
Conversions: b, c, d, f, and s

Front 69

If your conversion character doesn't match your argument type

Back 69

an exception
will be thrown