Field Detail

• JAVA_GOOD_START_CHARS

  public static final java.lang.String JAVA_GOOD_START_CHARS

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  Constant Field Values

• JAVA_GOOD_NONSTART_CHARS

  public static final java.lang.String JAVA_GOOD_NONSTART_CHARS

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  Constant Field Values

• JAVA_GENERATED_IDENTIFIER_START_CHARS

  public static final java.lang.String JAVA_GENERATED_IDENTIFIER_START_CHARS

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  Constant Field Values

• JAVA_GENERATED_IDENTIFIERNONSTART_CHARS

  public static final java.lang.String JAVA_GENERATED_IDENTIFIERNONSTART_CHARS

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  Constant Field Values

• BASE64_VALID_CHARS

  public static final java.lang.String BASE64_VALID_CHARS

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  Constant Field Values

• ID_VALID_START_CHARS

  public static final java.lang.String ID_VALID_START_CHARS

  See Also:

  Constant Field Values

• ID_VALID_NONSTART_CHARS

  public static final java.lang.String ID_VALID_NONSTART_CHARS

  See Also:

  Constant Field Values

Constructor Detail

• Identifiers

  public Identifiers()

Method Detail

• makeRandomId

  public static java.lang.String makeRandomId(int l)

  makes a random id string (letters and numbers) of the given length; starts with letter (upper or lower) so can be used as java-id; tests ensure random distribution, so random ID of length 5 is about 2^29 possibilities

  With ID of length 4 it is not unlikely (15% chance) to get duplicates in the first 2000 attempts. With ID of length 8 there is 1% chance to get duplicates in the first 1M attempts and 50% for the first 16M.

  implementation is efficient, uses char array, and makes one call to random per 5 chars; makeRandomId(5) takes about 4 times as long as a simple Math.random call, or about 50 times more than a simple x++ instruction; in other words, it's appropriate for contexts where random id's are needed, but use efficiently (ie cache it per object), and prefer to use a counter where feasible

  in general this is preferable to base64 as is more portable, can be used throughout javascript (as ID's which don't allow +) or as java identifiers (which don't allow numbers in the first char)

• makeIdFromHash

  public static java.lang.String makeIdFromHash(long d)

  creates a short identifier comfortable in java and OS's, given an input hash code

  result is always at least of length 1, shorter if the hash is smaller

• makeRandomJavaId

  public static java.lang.String makeRandomJavaId(int l)

  makes a random id string (letters and numbers) of the given length; starts with letter (upper or lower) so can be used as java-id; tests ensure random distribution, so random ID of length 5 is about 2^29 possibilities

  implementation is efficient, uses char array, and makes one call to random per 5 chars; makeRandomId(5) takes about 4 times as long as a simple Math.random call, or about 50 times more than a simple x++ instruction; in other words, it's appropriate for contexts where random id's are needed, but use efficiently (ie cache it per object), and prefer to use a counter where feasible

• randomDouble

  public static double randomDouble()

• randomLong

  public static long randomLong()

• randomBoolean

  public static boolean randomBoolean()

• randomInt

  public static int randomInt()

• randomInt

  public static int randomInt(int upbound)

  returns in [0,upbound)

• randomBytes

  public static byte[] randomBytes(byte[] buf)

  returns the array passed in

• randomBytes

  public static byte[] randomBytes(int length)

• makeRandomBase64Id

  public static java.lang.String makeRandomBase64Id(int length)

• getBase64IdFromValue

  public static java.lang.String getBase64IdFromValue(long value)

• getBase64IdFromValue

  public static java.lang.String getBase64IdFromValue(long value,
                                      int length)

• appendBase64IdFromValueOfLength

  public static void appendBase64IdFromValueOfLength(long value,
                                     int length,
                                     java.lang.StringBuffer sb)

• appendBase64IdFromValueOfLength

  public static void appendBase64IdFromValueOfLength(long value,
                                     int length,
                                     java.lang.StringBuilder sb)

• isValidToken

  public static boolean isValidToken(java.lang.String token,
                     java.lang.String validStartChars,
                     java.lang.String validSubsequentChars)