File	Doc	Category	Size	Date	Package
StringTokenizer.java	API Doc	Java SE 5 API	14150	Fri Aug 26 14:57:24 BST 2005	java.util

StringTokenizer

• java.lang.Object

Fields Summary
private int	currentPosition
private int	newPosition
private int	maxPosition
private String	str
private String	delimiters
private boolean	retDelims
private boolean	delimsChanged
private int	maxDelimCodePoint maxDelimCodePoint stores the value of the delimiter character with the highest value. It is used to optimize the detection of delimiter characters. It is unlikely to provide any optimization benefit in the hasSurrogates case because most string characters will be smaller than the limit, but we keep it so that the two code paths remain similar.
private boolean	hasSurrogates If delimiters include any surrogates (including surrogate pairs), hasSurrogates is true and the tokenizer uses the different code path. This is because String.indexOf(int) doesn't handle unpaired surrogates as a single character.
private int[]	delimiterCodePoints When hasSurrogates is true, delimiters are converted to code points and isDelimiter(int) is used to determine if the given codepoint is a delimiter.

Constructors Summary
public StringTokenizer(String str, String delim, boolean returnDelims) Constructs a string tokenizer for the specified string. All characters in the delim argument are the delimiters for separating tokens. If the returnDelims flag is true, then the delimiter characters are also returned as tokens. Each delimiter is returned as a string of length one. If the flag is false, the delimiter characters are skipped and only serve as separators between tokens. Note that if delim is null, this constructor does not throw an exception. However, trying to invoke other methods on the resulting StringTokenizer may result in a NullPointerException. param str a string to be parsed. param delim the delimiters. param returnDelims flag indicating whether to return the delimiters as tokens. exception NullPointerException if str is null currentPosition = 0; newPosition = -1; delimsChanged = false; this.str = str; maxPosition = str.length(); delimiters = delim; retDelims = returnDelims; setMaxDelimCodePoint();
public StringTokenizer(String str, String delim) Constructs a string tokenizer for the specified string. The characters in the delim argument are the delimiters for separating tokens. Delimiter characters themselves will not be treated as tokens. Note that if delim is null, this constructor does not throw an exception. However, trying to invoke other methods on the resulting StringTokenizer may result in a NullPointerException. param str a string to be parsed. param delim the delimiters. exception NullPointerException if str is null this(str, delim, false);
public StringTokenizer(String str) Constructs a string tokenizer for the specified string. The tokenizer uses the default delimiter set, which is " \t\n\r\f": the space character, the tab character, the newline character, the carriage-return character, and the form-feed character. Delimiter characters themselves will not be treated as tokens. param str a string to be parsed. exception NullPointerException if str is null this(str, " \t\n\r\f", false);

Methods Summary
public int	countTokens() Calculates the number of times that this tokenizer's nextToken method can be called before it generates an exception. The current position is not advanced. return the number of tokens remaining in the string using the current delimiter set. see java.util.StringTokenizer#nextToken() int count = 0; int currpos = currentPosition; while (currpos < maxPosition) { currpos = skipDelimiters(currpos); if (currpos >= maxPosition) break; currpos = scanToken(currpos); count++; } return count;
public boolean	hasMoreElements() Returns the same value as the hasMoreTokens method. It exists so that this class can implement the Enumeration interface. return true if there are more tokens; false otherwise. see java.util.Enumeration see java.util.StringTokenizer#hasMoreTokens() return hasMoreTokens();
public boolean	hasMoreTokens() Tests if there are more tokens available from this tokenizer's string. If this method returns true, then a subsequent call to nextToken with no argument will successfully return a token. return true if and only if there is at least one token in the string after the current position; false otherwise. /* * Temporarily store this position and use it in the following * nextToken() method only if the delimiters haven't been changed in * that nextToken() invocation. */ newPosition = skipDelimiters(currentPosition); return (newPosition < maxPosition);
private boolean	isDelimiter(int codePoint) for (int i = 0; i < delimiterCodePoints.length; i++) { if (delimiterCodePoints[i] == codePoint) { return true; } } return false;
public java.lang.Object	nextElement() Returns the same value as the nextToken method, except that its declared return value is Object rather than String. It exists so that this class can implement the Enumeration interface. return the next token in the string. exception NoSuchElementException if there are no more tokens in this tokenizer's string. see java.util.Enumeration see java.util.StringTokenizer#nextToken() return nextToken();
public java.lang.String	nextToken(java.lang.String delim) Returns the next token in this string tokenizer's string. First, the set of characters considered to be delimiters by this StringTokenizer object is changed to be the characters in the string delim. Then the next token in the string after the current position is returned. The current position is advanced beyond the recognized token. The new delimiter set remains the default after this call. param delim the new delimiters. return the next token, after switching to the new delimiter set. exception NoSuchElementException if there are no more tokens in this tokenizer's string. exception NullPointerException if delim is null delimiters = delim; /* delimiter string specified, so set the appropriate flag. */ delimsChanged = true; setMaxDelimCodePoint(); return nextToken();
public java.lang.String	nextToken() Returns the next token from this string tokenizer. return the next token from this string tokenizer. exception NoSuchElementException if there are no more tokens in this tokenizer's string. /* * If next position already computed in hasMoreElements() and * delimiters have changed between the computation and this invocation, * then use the computed value. */ currentPosition = (newPosition >= 0 && !delimsChanged) ? newPosition : skipDelimiters(currentPosition); /* Reset these anyway */ delimsChanged = false; newPosition = -1; if (currentPosition >= maxPosition) throw new NoSuchElementException(); int start = currentPosition; currentPosition = scanToken(currentPosition); return str.substring(start, currentPosition);
private int	scanToken(int startPos) Skips ahead from startPos and returns the index of the next delimiter character encountered, or maxPosition if no such delimiter is found. int position = startPos; while (position < maxPosition) { if (!hasSurrogates) { char c = str.charAt(position); if ((c <= maxDelimCodePoint) && (delimiters.indexOf(c) >= 0)) break; position++; } else { int c = str.codePointAt(position); if ((c <= maxDelimCodePoint) && isDelimiter(c)) break; position += Character.charCount(c); } } if (retDelims && (startPos == position)) { if (!hasSurrogates) { char c = str.charAt(position); if ((c <= maxDelimCodePoint) && (delimiters.indexOf(c) >= 0)) position++; } else { int c = str.codePointAt(position); if ((c <= maxDelimCodePoint) && isDelimiter(c)) position += Character.charCount(c); } } return position;
private void	setMaxDelimCodePoint() Set maxDelimCodePoint to the highest char in the delimiter set. if (delimiters == null) { maxDelimCodePoint = 0; return; } int m = 0; int c; int count = 0; for (int i = 0; i < delimiters.length(); i += Character.charCount(c)) { c = delimiters.charAt(i); if (c >= Character.MIN_HIGH_SURROGATE && c <= Character.MAX_LOW_SURROGATE) { c = delimiters.codePointAt(i); hasSurrogates = true; } if (m < c) m = c; count++; } maxDelimCodePoint = m; if (hasSurrogates) { delimiterCodePoints = new int[count]; for (int i = 0, j = 0; i < count; i++, j += Character.charCount(c)) { c = delimiters.codePointAt(j); delimiterCodePoints[i] = c; } }
private int	skipDelimiters(int startPos) Skips delimiters starting from the specified position. If retDelims is false, returns the index of the first non-delimiter character at or after startPos. If retDelims is true, startPos is returned. if (delimiters == null) throw new NullPointerException(); int position = startPos; while (!retDelims && position < maxPosition) { if (!hasSurrogates) { char c = str.charAt(position); if ((c > maxDelimCodePoint) || (delimiters.indexOf(c) < 0)) break; position++; } else { int c = str.codePointAt(position); if ((c > maxDelimCodePoint) || !isDelimiter(c)) { break; } position += Character.charCount(c); } } return position;