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Odysseus_110:
terryang 写道lz加上时间也不太合适,刷新太快的话还是 ...
$.getJSON 缓存 -
ll.james:
5楼的,真管用通知公告模块A.通知公告的类型没有实现控制B.通 ...
$.getJSON 缓存 -
zranye:
这样虽然能启动,但是会出现乱码
resin 无法启动 com.caucho.config.LineConfigException: -
酒杯中的大海:
学习了!!!~
struts 文件上传 乱码 -
酒杯中的大海:
牛逼,膜拜~
struts 文件上传 乱码
Note: Please feel free to modify, improve, circulate, and repost these notes at will. – Dave Allen
Collections Framework (only Maps, Iterators do not extend java.io.Collection Interface)
Collection interface |
add(E) addAll (Collection<e>) remove(Object) removeAll ( Collection<?>) contains(Object) size() iterator () isEmpty () Object[] toArray () – returns Object array, must cast – e.g. String[] str = (String[]) myCollection.toArray (); T[] toArry (T[] a) – returns typecast array – syntax: String[] str = myCollection.toArray (new String[0]); |
Map interface, SortedMap interface extends Map |
put(keyObject , valueObject ) – inserts key/value pair, will overwrite duplicate keyObject values keySet () – returns set of keys values() – returns collection of values get(Object), remove(Object), size(), clear() entrySet () – returns set of Map.Entry type (key/value pair) Map.Entry – a key/value pair, has getKey () and getValue () methods
Maps care about unique identifiers There is no add() method; Don’t have to override equals(Object) method to compile, but necessary to find objects |
HashMap |
|
Hashtable |
synchronized version of HashMap |
TreeMap |
Can have null values, but NO null keys |
LinkedHashMap (extends Hashmap ) |
maintains insertion order, slower updates, faster iteration than HashMap , order remains same if replacing duplicate key, can have null keys or values |
Set interface, SortedSet interface extends Set |
boolean add() – if element already exists, returns false and element not added Sets care about uniqueness |
HashSet |
|
LinkedHashSet (extends HashSet ) |
fastest iteration through items without duplicates (a Set) that maintains insertion order |
TreeSet <T> |
new TreeSet (), new TreeSet (Collection<E>), new TreeSet <T>(Comparator<? super E>) |
List interface |
Lists care about the index |
ArrayList |
fastest iteration through items with duplicates |
Vector |
synchronized version of ArrayList ; slower |
LinkedList |
addFirst (), getFirst ()
doubly linked, ideal for implementing a stack or maintaining an ordered sequence of objects when they are frequently inserted and removed from the middle of the sequence |
Queu interface |
peek() – returns highest priority entry without removing it poll() – returns highest priority entry and removes it offer() – adds entry |
PriorityQue |
|
Collections |
Collections.sort (Collection) Collections.sort (Collection, Comparator) Collections.binarySearch (collectionName , pattern) – must be sorted first Collections.binarySearch (collectionName , pattern, Comparator) – must be sorted first Collections.reverse () – reverses order of elements in List, doesn’t have to be sorted first Collections.reverserOrder () – returns Comparator that sorts in reverse, must b sorted first |
Arrays |
Arrays.sort (arrayToSort ) Arrays.binarySearch (arrayName , pattern), Arrays.binarySearch (collectionName , pattern, Comparator) – returns int index Arrays.asList (arrayName ) – returns List, changes to either returned list or original array will be reflected in the other |
Comparable interface |
int compareT o (SpecificObject Type ) returns negative int if this < Obj2 0 if Objects are equal positive int if this > Obj2 |
Comparator class |
int compare(SpecificObject Type1, SpecificObject Type2) – returns int with same meaning as above – substitute “SpecificObjectType1” for “this” |
Iterator |
boolean hasNext () next() – returns type Object which must be cast if no generic type is specified for iterator , even if Collection that called iterator () method has generics, like List<Integer>
Can use generics syntax to avoid explicit casting, e.g. Iterator <Dog> = dogs.iterator (); |
Dates
java.util.Date |
new Date() – date Object with current date new Date(long millis ) – millis since Jan 1, 1970
getTime () – returns long setTime (long millis )
internally stored as primitive long which is milliseconds between date and Jan 1, 1970 |
Calendar |
Calendar.getInstance () – gets default Calendar (almost always GregorianCalendar ) with current time Calendar.getInstance (Locale)
add( intField , intAmount ) – adds or decrements field. intAmount can be negative roll(intField , intAmount ) – larger parts of date will not be incremented/decremented, only the field specified set(intField , intValue ) get(intField ) – e.g. calendarInstance.get (Calendar.MONTH ); set() – various other set methods setTime (Date) getTime () – returns Date object, useful for passing to DateFormat setTimeInMillis (long millis ) getTimeInMillis () – returns long compareTo (Calendar)
NO new Calendar(), only instantiated using getInstance (), months are 0-based (January is 0) |
java.text . NumberFormat |
NumberFormat.getInstance (), NumberFormat.getInstance (Locale) – e.g. NumberFormat.getInstance (Locale.US ); NumberFormat.getNumberInstace ( ), NumberFormat.getNumberInstanceLocale () – same as getInstance ()? NumberFormat.getCurrencyInstance (), NumberFormat.getCurrencyInstance (Locale)
format(long), format(double) – takes various numbers to be formatted, returns String parse(String) – takes a String (must be formatted correctly to locale), returns a Number – e.g. parse(“$5,075”); setParseIntegerOnly ( boolean ) – whether to format and display digits after decimal. getMaximumFractionDigits (), getMinimumFractionDigits – get number of decimal places setMaximumFractionDigits (int), setMinimumFractionDigits – set number of decimal places get/setMinimum/MaximumIntegerDigits ()
Should only instantiated using getInstance () |
java.text . DateFormat |
getInstance () – returns DateFormat with default Locale, sometimes SHORT style getDateInstance () (has defaults, sometimes MEDIUM style),getDateInstance (styleConstant ), getDateInstance (styleConstant , Locale) parse(String) – converts String to a Date format(Date) – returns String with formatted Date
String format for each style possible default format – 0/8/01 7:46 PM DateFormat.SHORT – 9/8/01 DateFormat.MEDIUM – Sep 8, 2001 DateFormat.LONG – September 8, 2001 DateFormat.FULL – Saturday, September 8, 2001
There is no format( Calendar) method. Calendar must convert to Date first(using yourCalendar.getTime ()), then use format(Date) DateFormat’s Locale can only be set at instantiation using getInstance () – NO new DateFormat () |
java.util.Locale |
Locale.getDefault () – returns default Locale new Locale(stringLanguage ) new Locale(stringLanguage , stringCountry ) – e.g. new Locale(“it”, “IT”)
setDefault (Locale) getDisplayLanguage () – returns String of Language getDisplayLanguage (Locale) – displays language using language of Locale passed in getDisplayCountry () – returns String code getDisplayCountry (Locale) – displays language using language of Locale passed in) Locale.getAvailableLocales () – returns an array of Locales installed
used in Scanner, DateFormat , NumberFormat |
String Stuff
String |
new String(), new String(StringBuilder /Buffer) new String(“StringLiteral ”) new String(ExistingStringObject ) will create a new String object different than ExistingStringObject
length() charAt (int) concat (String) equalsIgnoreCase (String) substring(intIndex ) substring(startIntIndex , endIntIndexExclusive ) replace(char/stringRegex , char/stringReplacement ) replaceAll (char/stringRegex , char/stringReplacement ) replaceFirst (stringRegex , stringReplacement ) split(regex ) – returns String array of tokens, good for just small amount of data split(regex , IntLengthOfArrayReturned ) toLowerCase () toUpperCase () trim() – remove whitespace off ends toString () – returns a new String object
indexOf (char/String) indexOf (char/String, startingIntIndex ) lastIndex (char/String, startingIntIndex ) lastIndex (char/String, startingIntIndex ) contains(charSequence ) matches(regex ) – returns boolean indicating if regex matches string boolean startsWith (String) boolean startsWith (String, offsetIndex ) String format(“formattingString ”, args ) – returns String formatted to specs String format(Locale, “formattingString ”, args )
All methods return a String, do no alter original String NO insert() method (this is in StringBuilder/StringBuffer ) NO length member variable (this is for array) |
StringBuilder / StringBuffer |
append(xxx) – can append almost any char related type delete(intStartIndex , intEndIndexExclusive ) deleteCharAt () insert(intOffset , String) reverse() toString () length() substring(startIndexInclusive ) substring(startIndex , endIndexProbablyExclusive )
lastIndexOf (String) lastIndexOf (String, startSearchIndex ) replace(intStart , intEnd , String) setCharAt ()
StringBuffer is synchronized and slower. StringBuilder is not synchronized and faster equals() method is not overridden, so it compares references, not meaningful values – same as == |
java.util . Scanner |
new Scanner(File), new Scanner(stringToSearchOrTokenize )
useDelimiter (String) – can be regex useLocal (Locale) hasNext (), hasNextInt (), hasNextFloat (), hasNextXxx () – for all primitives EXCEPT char next(), nextInt (), nextFloat (), nextXxx – for all primitives EXCEPT char Scanner.close () – static method that should be used after done with file findInLine (regexString ) – returns String found
match() – returns MatchResult matchResult.groupCount () – method in MatchResult (not Scanner) matchResult.group (groupCountIndexInt ) – method in MatchResult (not Scanner)
Mostly used for tokenizing, but can also find regexes using findInLine () Default delimiter is whitespace |
java.util.regex . Pattern |
Pattern.compile (regex ) – returns new Pattern matcher(CharSequence ) – returns new Matcher split(regex ) – returns String array of matching patterns found in the CharSequence Pattern.matches (regex , stringtoSearch ) – returns Boolean indicating if string matches regex
/d digits /s whitespace /w word character (letters, digits, or underscores) [af ] a or f [a-f] a, b, c, d, e, f [a-dA -D] A,a,B,b,C,c,D,d . any character + greedy one or more (e.g. /d+ means one or more digits) * greedy zero or more (e.g. filename/d*) ? greedy zero or more occurrences(e.g. /d?) ^ not (e.g. [^abc ] excludes abc )
String pattern = “\\d” creates string regex with \d. String pattern = “\\.” creates string regex with . |
java.util.regex . Matcher |
find() – returns boolean indicating a match’s existence, advances to next index that matches, left to right start() – returns starting index group() – returns string that matches
Probably Not on Exam replaceAll (stringReplacement ) replaceFirst (stringReplacement ) appendReplacement (StringBuffer , stringReplacement ) -- appendTail (StringBuffer ) – to be used after appendReplacement |
java.util . Formatter |
new Formatter(), new Formatter(Appendable , Locale) – Appendable can be StringBuilder/StringBuffer , BufferedWriter , FileWriter , but NOT String
format(“formattingString ”, args ) – returns formatted String |
Serialization (package java.io , classes must implement Serializable to be serialized)
FileOutputStream |
new FileOutputStream (stringFileName ) new FileOutputStream (File) |
ObjectOutputStream |
defaultWriteObject () writeObject (Object) writeInt (int), writeFloat (float), writeXxx (xxx) |
FileInputStream |
new FileInputStream (stringFileName ) new FileInputStream (File) |
ObjectInputStream |
defaultReadObject () readObject () – returns Object, must be cast before use readInt (), readFloat (), readXxx () |
转自
<!----> <!---->
发表评论
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ant 正则表达式 换行符
2011-02-05 23:05 3076SSH上传文件的时候 报错 无法上传文件 可能是因为存在本地 ... -
ftp 文件上传 无法上传中文名称
2009-08-12 14:11 2242代码参考上一篇《ftp文件上传 文件损坏》 ... -
ftp 文件上传 文件损坏
2009-08-12 13:35 2801这里演示的是配置好ftp服务器后,通过java ... -
SCJP 5.0 Study Notes(3)
2009-07-03 22:11 848Enums <!---->· &l ... -
SCJP 5.0 Study Notes(2)
2009-07-03 21:48 945Encapsulation, coupling, cohesi ... -
C语言
2008-09-01 08:23 0(1)指针变量初始化的方法 int a;int *p=& ... -
tomcat
2008-07-08 17:38 0<Context crossContex ... -
SCJP notes
2008-06-23 23:12 1344The default constructor has the ... -
Computer Science
2008-06-03 15:55 1278中文名称 :计算机科学 ... -
Integer中用静态内部类所作的缓存
2008-05-22 20:49 1530今天在做一个题目时,发现一个奇怪的Integer方法。 pub ... -
图片切割的研究
2008-05-15 14:35 0切割图片 -
SCJP tips
2008-05-09 10:21 12171. Thread t1 = new Thread(&quo ...
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