[Chapter 17] StringTokenizer

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| Chapter 17 The java.util Package |

# StringTokenizer

## Name

StringTokenizer

## Synopsis

Class Name:

  `java.util.StringTokenizer`

Superclass:

  `java.lang.Object`

Immediate Subclasses:

  None

Interfaces Implemented:

  `java.util.Enumeration`

Availability:

  JDK 1.0 or later

## Description

The `StringTokenizer` class implements a simple, delimiter-based string tokenizer. In other words, a `StringTokenizer` is used to break a `String` into tokens separated by delimiter characters. By default, the class uses the standard whitespace characters as delimiters, but you can specify any delimiter characters you want, either when the `StringTokenizer` is created or on a token-by-token basis. You can also specify whether the delimiters are returned as tokens or not. A `StringTokenizer` returns the tokens in its `String` in order, either as `String` objects or as `Objects` in an `Enumeration`.

`StringTokenizer` shouldn't be confused with the more complex `java.io.StreamTokenizer`, which parses a stream into tokens that are similar to those used in the Java language.

## Class Summary

    public class java.util.StringTokenizer extends java.lang.Object
                 implements java.util.Enumeration {
      // Constructors
      public StringTokenizer(String str);
      public StringTokenizer(String str, String delim);
      public StringTokenizer(String str, String delim, boolean returnTokens);
      // Instance Methods
      public int countTokens();
      public boolean hasMoreElements();
      public boolean hasMoreTokens();
      public Object nextElement();
      public String nextToken();
      public String nextToken(String delim);
    }

## Constructors

### StringTokenizer

#### public StringTokenizer(String str)

Parameters

  `str`

    The `String` to be tokenized.

Description

  This constructor creates a `StringTokenizer` that breaks apart the given string using the default delimiter characters. The default delimiters are the standard whitespace characters: space, tab (`\t`), carriage return (`\r`), and newline (`\n`).

#### public StringTokenizer(String str, String delim)

Parameters

  `str`

    The `String` to be tokenized.

  `delim`

    The delimiter characters.

Description

  This constructor creates a `StringTokenizer` that breaks apart the given string using the characters in `delim` as delimiter characters.

####

     public StringTokenizer(String str, String delim, boolean returnTokens)

Parameters

  `str`

    The `String` to be tokenized.

  `delim`

    The delimiter characters.

  `returnTokens`

    A `boolean` value that indicates whether or not delimiters should be returned as tokens.

Description

  This constructor creates a `StringTokenizer` that breaks apart the given string using the characters in `delim` as delimiter characters. If `returnTokens` is `true`, the delimiters are returned as tokens; otherwise they are skipped.

## Instance Methods

### countTokens

#### public int countTokens()

Returns

  The number of tokens remaining in the string.

Description

  This method returns the number of tokens that remain in the string, which is the same as the number of times `nextToken()` can be called before an exception is thrown.

### hasMoreElements

#### public boolean hasMoreElements()

Returns

  `true` if there are more tokens to be returned; `false` otherwise.

Implements

  `Enumeration.hasMoreElements()`

Description

  This method returns the result of calling `hasMoreTokens()`.

### hasMoreTokens

#### public boolean hasMoreTokens()

Returns

  `true` if there are more tokens to be returned; `false` otherwise.

Description

  This method returns `true` if this object has more tokens to return.

### nextElement

#### public Object nextElement()

Returns

  The next token as an `Object`.

Throws

  `NoSuchElementException`

    If there are no more tokens in the string.

Implements

  `Enumeration.nextElement()`

Description

  This method returns result of calling `nextToken()`.

### nextToken

#### public String nextToken()

Returns

  The next token as a `String`.

Throws

  `NoSuchElementException`

    If there are no more tokens in the string.

Description

  This method returns the next token.

#### public String nextToken(String delim)

Parameters

  `delim`

    The delimiter characters.

Returns

  The next token as a `String`.

Throws

  `NoSuchElementException`

    If there are no more tokens in the string.

Description

  This method sets the delimiter characters to the characters in the given string and then returns the next token. The change in delimiters persists until another call to this method changes them again.

## Inherited Methods

Method | Inherited From | Method | Inherited From
--- | --- | --- | ---
`clone()` | `Object` | `equals(Object)` | `Object`
`finalize()` | `Objxect` | `getClass()` | `Object`
`hashCode()` | `Object` | `notify()` | `Object`
`notifyAll()` | `Object` | `toString()` | `Object`
`wait()` | `Object` | `wait(long)` | `Object`
`wait(long, int)` | `Object` |  |

## See Also

`Enumeration`, `NoSuchElementException`, `StreamTokenizer`, `String`

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