Savitch Java Ch. 9

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CHAPTER 3
StringTokenizer
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StringTokenizer CLASS

• There are BufferedReader methods to read a line
  (i.e. a record) and a character, but not just a
  single word (i.e. a field).
• For example
• William Smith 555-55-5555 76542.56
• Lisa Jackson 444-44-4444 77654.78
• Use method readLine to input data ? entire line
  read as a string.
• Need to break each line into meaningful units of
  data called tokens.
• But cannot do this by using BufferedReader.

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Tokenizing a String

• class StringTokenizer
• Contained in package java.util
• Tokens usually delimited by default whitespace
  characters (space, tab, newline)
• You can specify other delimiters (the character
  or characters that separate words)
• Contains methods
• public StringTokenizer(String str, String
  delimits)
• public int countTokens()
• public boolean hasMoreTokens()
• public String nextToken(String delimits)
• public String nextToken()

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StringTokenizer class

• To use the StringTokenizer class, create a
  StringTokenizer object initialized with the
  string to break apart.
• A token is a sequence of characters separated by
  white space, comma, tab, newline.
• nextToken() method
• retrieves the next token from the string
  tokenizer
• Throws NoSuchElementException if no more tokens
  to return.
• countTokens() method
• Returns the number of tokens remaining to be
  returned by nextToken

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• hasMoreTokens() method
• Tests if there are more tokens available from
  this tokenizers string.
• When used with nextToken, it returns true as long
  as nextToken has not yet returned all the tokens
  in the string, returns false otherwise.

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Constructor METHODS

• public StringTokenizer(String theString)
• Constructor for a tokenizer using whitespace
  characters to find tokens in theString.
• public StringTokenizer(String theString, String
  delimeters)
• Constructor for a tokenizer that will user the
  characters in the string delimiters as
  separators to find tokens in theString.

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Tokenizing a String

• Create a StringTokenizer object store the
  string in the created object.
• StringTokenizer tokenizer
• new StringTokenizer(Hello there!)
• Use the method nextTokenizer with the object
  (tokenizer) to retrieve the token from the
  string.
• str1 tokenizer.nextToken()
• str1 tokenizer.nextToken()

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StringTokenizerClass Exercise

• 1. BufferedReader keyboard new
• BufferedReader(new InputStreamReader(System.in)
  
• 2. StringTokenizer tokenizer
• 3. String inputLine, name
• 4. int num
• 5. double decNum
• 6. inputLine keyboard.readLine()
• 7. tokenizer new StringTokenizer(inputLine)
• 8. name tokenizer.nextToken()
• 9. num Integer.parseInt(tokenizer.nextToken())
  
• 10. decNum Double.parseDouble(tokenizer.nextToke
  n())
• Have the following input data- Mickey 97
  158.50

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Example StringTokenizer

• Display the words separated by any of the
  following characters space, new line (\n),
  period (.) or comma (,).

String inputLine keyboard.readLine() StringTok
enizer wordFinder new StringTokenizer(inputLine
, " \n.,") while(wordFinder.hasMoreTokens())
System.out.println(wordFinder.nextToken())
Question2bor!tooBee
Entering "Question,2b.or !tooBee." gives this
output
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Text File Input (Example)

• while (record ! null)
• System.out.println("Here goes " record)
• StringTokenizer wordFinder new
  StringTokenizer(record,",")
• while (wordFinder.hasMoreTokens() )
• System.out.println(wordFinder.nextToken() )
• record inFile.readLine()