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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

1. Use method readLine to input data entire line read as a string.

2. Need to break each line into meaningful units of data called tokens.

3. 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 tokenizer’s

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.nextToken());

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();

StringTokenizer 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();

}