6.3 String ? StringBuffer ?

1
??? ????????

• 6.1 ?????
• 6.2 ???
• 6.3 String ? StringBuffer ?
• 6.4 ??????
• 6.5 ?????
• 6.6 ?????
• 6.7 Math ?

2
6.1 ?????
??? ????????

• public class Echo
• public static void main (String args)
• for (int i 0 i lt args.length i)
• System.out.println(argsi)
• ??
• java Echo Drink Hot Java
• Drink
• Hot
• Java

??
??
java Echo Drink Hot Java Drink Hot Java
3
6.1 ?????
??? ????????

• ??
• ??????????,??????????????
• ??
• int firstArg
• if (args.length gt 0)
• firstArg Integer.parseInt(args0)

4
6.2 ???
??? ????????

• ?????????????java.lang????????????,????????,??????
  ???

5
6.2 ???
??? ????????

• ?????????????java.lang????????????,????????,??????
  ???
• ??
• int pInt 500
• Integer i1 new Integer( pInt)
• int p2 i1. parseInt()

6
6.3 String ? StringBuffer ?
??? ????????

• ??
• String ??????
• SrtingBuffer ????????
• 2. ??String ? StringBuffer
• String "Gobbledy ." new
  String("Gobbledy ")
• StringBuffer StringBuffer()
• StringBuffer( int capacity)
• StringBuffer( String
  initialString)

7
6.3 String ? StringBuffer ?
??? ????????

• 3. String? StringBuffer??????
• String charAt ,length, indexOf , lastIndexOf,
  substring , toLowerCase , toUpperCase ,equals
  , equalsIgnoreCase ??
• StringBufferappend , insert , reverse ,
  setCharAt , setLength
• ???example63String.txt

8
6.3 String ? StringBuffer ?
??? ????????

• ?????????
• ?????
• toString ???????Character, Integer, Double?
• valueOf ??String.valueOf()
• System.out.println(String.valueOf(Math.PI))

9
6.3 String ? StringBuffer ?
??? ????????

• ?????????
• ?????(Integer, Double, Float, and
  Long)?valueOf()???????
• ??
• String piStr "3.14159"
• Float pi Float.valueOf(piStr)

10
6.3 String ? StringBuffer ?
??? ????????

• 6. ????java ???
• ??????????????,java???????String and
  StringBuffer?
• ??
• "Hello World!"
• int len Goodbye Cruel World.length()
• String s "Hola Mundo"
• String cat "cat" System.out.println("con"
  cat "enation")
• System.out.println("Java's Number " 1)

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6.4 ??????
??? ????????

1. System?
2. ??????(I/O)?
3. ????

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6.4 ??????
??? ????????

• System?
• System?????????????????System???????,?????????????
  ????
• ??
• class UserNameTest
• public static void main(String args)
• String name
• name System.getProperty("user.name")
• System.out.println(name)

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6.4 ??????
??? ????????

• ??????(I/O)?
• System.in ????
• System.out ????
• System.err ??????
• Standard Output ? Error Streams ???????
• print, println, and write
• ??
• System.out.print("Duke is not a penguin!\n")
• ???System.out.println("Duke is not a penguin!")

14
6.4 ??????
??? ????????

• ??????(I/O)?
• print and println ???
• Object, String, char, int, long, float,
  double, and boolean.
• println()?????,?????
• ???DataTypePrintTest.java

15
6.4 ??????
??? ????????

• 3. ????
• ?????????????????????key/value ????
• java.vm.version 1.2.2
• path.separator
• file.separator /
• user.home /home/basham
• java.specification.vendor Sun Microsystems Inc.
• user.language en
• user.name basham

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6.4 ??????
??? ????????

• 3. ????
• ?????
• System. getProperties????Properties??
• System. getProperty?????????
• ??
• Properties props System.getProperties()
• System.getProperty("path.separator")

17
6.5 ?????
??? ????????

• The Collections API
• ??collection?????,??????object???
• The Collection API ???3??? ,??object???
• Collection ?? objects ,???????,???????
• ?List(??)????????????,???????
• ??Set(?)???????,????????????

18
6.5 ?????
??? ????????
19
6.5 ?????
??? ????????

• ???
• setExmple.java
• ListExmple.java

20
6.5 ?????
??? ????????

• Map
• Map(??) ???-?????(?),?????????????
• HashMap?????????(????Hashtable)????-????????,???
  ??????????

21
6.5 ?????
??? ????????
22
6.5 ?????
??? ????????

• ???
• PrintingContainers.java
• ??containers??List, ??Set or Map
• ???
• FillingLists.java

23
6.5 ?????
??? ????????

• Container ??
• ???????
• ?????????
• ???Cat.java
• Dog.java
• CatsAndDogs.java

24
6.5 ?????
??? ????????

• Iterators???
• ????????????????
• An Iterator of a Set ?????
• ListIterator of a List ???????

25
6.5 ?????
??? ????????
26
6.5 ?????
??? ????????

• Iterators???
• ???CatsAndDogs2.java
• ???????
• HamsterMaze.java
• ?Iterators????Collection ?????Collection1.java

27
6.5 ?????
??? ????????

• ??List, LinkedList, ArrayList
• List(??) ???List??????
• ????????????
• List?Collection???????
• ?List?????????
• (ListIterator(?????),?????????????????,???????????
  ?????

28
6.5 ?????
??? ????????

• ??List, LinkedList, ArrayList
• ArrayList ??????????,???????????????,????????????
  ?ListIterator???ArrayList?????????,???????????
• LinkedList??????????????????????????????,???.
  ???addFirst(),addLast(),getFirst(),getLast(),remov
  eFirst()??removeLast()(?????????????),????????????
  ???????????

29
6.5 ?????
??? ????????

• ?LinkedList????(queue)???
• ???Queue.java
• Map????
• Map1.java

30
6.6 ?????
??? ????????

• .??Arrays?????????????????????sort()?binarySearch
  (),??????String?Object?
• ???Array1.java

31
6.6 ?????
??? ????????

• . ?????????????????????(List)???????????????????C
  ollections?,sort(List)????????Comparable?????????
  binarySearch(List,Object)

32
6.5 ?????
??? ????????

• ??
• ?????????????????????????????????????????????,????
  ??
• Colloction????????,?Map???????
• List????????????,???????????,????????????
• ArrayList?????????LinkedList??????????????
• LinkedList ?????????
• Map ??????object-object?HashMap???????

33
6.5 ?????
??? ????????

• ??
• Set ?????????HashSet?????????

34
6.5 Enumeration ??
??? ????????

• Enumeration ??????????????????
• nextElement()???????
• hasMoreElements()??????????????
• ??
• Enumeration ??????????????

35
6.6 Vector ?
??? ????????

• Vector ??????????????????????????
• ??????????????Vector?????????????
• ???example66Vector.txt

36
6.7 ?? Stack
??? ????????

• Stack????Vector?,???Vector?????????????????
• ??Stack? new Stack()
• ????
• Object push(Object o)
• Object pop()
• Object peek()
• boolean empty()
• int search(Object o)
• ???example67Stack.txt

37
6.8 ??? Hashtable
??? ????????

• ????????????????(key/element)?????????????????????
  ??
• ????????
• put(Object key, Object value)
• get(Object key)
• remove(Object Key)
• elements()
• keys()
• size()
• isEmpty()
• ??? example68HashApp.txt

38
6.8 ??? Hashtable
??? ????????

• ?????????????????????????????????????
• ???example68Hashtable.txt

39
6.9 StringTokenizer ?
??? ????????

• StringTokenizer ?????String???????????????????????
  ??????????Enumeration???
• ????????
• hasMoreTokens()
• nextToken()
• countTokens()
• nextElement()
• hasMoreElements()
• ???example69Token.txt

40
6.10 Math ?
??? ????????

• Math?????????????,???????????????????
• ??
• public class MathApp
• public static void main(String args)
• System.out.println(Math.E)
• System.out.println(Math.PI)
• System.out.println(Math.abs(-1))
• System.out.println(Math.max(3,5))
• for(int i0ilt5i)
• System.out.print(Math.random()" ")
• System.out.println()

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• ???????.txt