Util (RRD4J 3.0 API)

java.lang.Object
- org.rrd4j.core.Util

```
public class Util
extends Object
```
Class defines various utility functions used in Rrd4j.

Author:

Sasa Markovic

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Util.Xml
Various DOM utility functions.

Nested Classes
Modifier and Type	Class and Description
`static class`	`Util.Xml` Various DOM utility functions.

Field Summary

Fields
Modifier and Type	Field and Description
`static double`	`MAX_DOUBLE` Constant `MAX_DOUBLE=Double.MAX_VALUE`
`static long`	`MAX_LONG` Constant `MAX_LONG=Long.MAX_VALUE`
`static double`	`MIN_DOUBLE` Constant `MIN_DOUBLE=-Double.MAX_VALUE`
`static long`	`MIN_LONG` Constant `MIN_LONG=-Long.MAX_VALUE`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static boolean`	`equal(double x, double y)` Compares two doubles but treats all NaNs as equal.
`static boolean`	`fileExists(String filename)` Checks if the file with the given file name exists
`static String`	`formatDouble(double x)` Formats double as a string using exponential notation (RRDTool like).
`static Calendar`	`getCalendar(Date date)` Returns `Calendar` object for the given Date object
`static Calendar`	`getCalendar(long timestamp)` Returns `Calendar` object for the given timestamp (in seconds, without milliseconds)
`static Calendar`	`getCalendar(String timeStr)` Creates Calendar object from a string.
`static String`	`getCanonicalPath(String path)` Returns canonical file path for the given file path
`static Date`	`getDate(long timestamp)` Returns `Date` object for the given timestamp (in seconds, without milliseconds)
`static String`	`getFileSeparator()` Returns file system separator string.
`static String`	`getLapTime()` Function used for debugging purposes and performance bottlenecks detection.
`static long`	`getLastModified(String file)` Returns last modification time for the given file.
`static String`	`getRrd4jDemoDirectory()` Returns path to directory used for placement of Rrd4j demo graphs and creates it if necessary.
`static String`	`getRrd4jDemoPath(String filename)` Returns full path to the file stored in the demo directory of Rrd4j
`static String`	`getRrd4jHomeDirectory()` Returns the root directory of the Rrd4j distribution.
`static long`	`getTime()` Returns current timestamp in seconds (without milliseconds).
`static long`	`getTimestamp()` Just an alias for `getTime()` method.
`static long`	`getTimestamp(Calendar gc)` Returns timestamp (unix epoch) for the given Calendar object
`static long`	`getTimestamp(Date date)` Returns timestamp (unix epoch) for the given Date object
`static long`	`getTimestamp(int year, int month, int day)` Returns timestamp (unix epoch) for the given year, month and day.
`static long`	`getTimestamp(int year, int month, int day, int hour, int min)` Returns timestamp (unix epoch) for the given year, month, day, hour and minute.
`static long`	`getTimestamp(String atStyleTimeSpec)` Parses at-style time specification and returns the corresponding timestamp.
`static long[]`	`getTimestamps(String atStyleTimeSpec1, String atStyleTimeSpec2)` Parses two related at-style time specifications and returns corresponding timestamps.
`static String`	`getUserHomeDirectory()` Returns path to user's home directory.
`static boolean`	`isDouble(String s)` Checks if a string can be parsed as double.
`static double`	`max(double[] values)` Finds max value for an array of doubles (NaNs are ignored).
`static double`	`max(double x, double y)` Returns the greater of two double values, but treats NaN as the smallest possible value.
`static double`	`min(double[] values)` Finds min value for an array of doubles (NaNs are ignored).
`static double`	`min(double x, double y)` Returns the smaller of two double values, but treats NaN as the greatest possible value.
`static long`	`normalize(long timestamp, long step)` Rounds the given timestamp to the nearest whole "step".
`static boolean`	`parseBoolean(String valueStr)` Parses input string as a boolean value.
`static Paint`	`parseColor(String valueStr)` Parses input string as color.
`static double`	`parseDouble(String valueStr)` Parses input string as a double value.
`static String`	`sprintf(Locale l, String format, Object... args)` Equivalent of the C-style sprintf function.
`static double`	`sum(double x, double y)` Calculates sum of two doubles, but treats NaNs as zeros.
`static double[]`	`toDoubleArray(long[] array)` Converts an array of long primitives to an array of doubles.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - MAX_LONG
```
public static final long MAX_LONG
```
    Constant MAX_LONG=Long.MAX_VALUE
    
    See Also:
    
    Constant Field Values
  - MIN_LONG
```
public static final long MIN_LONG
```
    Constant MIN_LONG=-Long.MAX_VALUE
    
    See Also:
    
    Constant Field Values
  - MAX_DOUBLE
```
public static final double MAX_DOUBLE
```
    Constant MAX_DOUBLE=Double.MAX_VALUE
    
    See Also:
    
    Constant Field Values
  - MIN_DOUBLE
```
public static final double MIN_DOUBLE
```
    Constant MIN_DOUBLE=-Double.MAX_VALUE
    
    See Also:
    
    Constant Field Values
- Method Detail
  - toDoubleArray
```
public static double[] toDoubleArray(long[] array)
```
    Converts an array of long primitives to an array of doubles.
    
    Parameters:
    
    array - input array of long values.
    
    Returns:
    
    Same array but with all values as double.
  - getTime
```
public static long getTime()
```
    Returns current timestamp in seconds (without milliseconds). Returned timestamp is obtained with the following expression:
    (System.currentTimeMillis() + 500L) / 1000L
    
    Returns:
    
    Current timestamp
  - getTimestamp
```
public static long getTimestamp()
```
    Just an alias for getTime() method.
    
    Returns:
    
    Current timestamp (without milliseconds)
  - normalize
```
public static long normalize(long timestamp,
                             long step)
```
    Rounds the given timestamp to the nearest whole "step". Rounded value is obtained from the following expression:
    timestamp - timestamp % step;
    
    Parameters:
    
    timestamp - Timestamp in seconds
    
    step - Step in seconds
    
    Returns:
    
    "Rounded" timestamp
  - max
```
public static double max(double x,
                         double y)
```
    Returns the greater of two double values, but treats NaN as the smallest possible value. Note that Math.max() behaves differently for NaN arguments.
    
    Parameters:
    
    x - an argument
    
    y - another argument
    
    Returns:
    
    the lager of arguments
  - min
```
public static double min(double x,
                         double y)
```
    Returns the smaller of two double values, but treats NaN as the greatest possible value. Note that Math.min() behaves differently for NaN arguments.
    
    Parameters:
    
    x - an argument
    
    y - another argument
    
    Returns:
    
    the smaller of arguments
  - sum
```
public static double sum(double x,
                         double y)
```
    Calculates sum of two doubles, but treats NaNs as zeros.
    
    Parameters:
    
    x - First double
    
    y - Second double
    
    Returns:
    
    Sum(x,y) calculated as Double.isNaN(x)? y: Double.isNaN(y)? x: x + y;
  - formatDouble
```
public static String formatDouble(double x)
```
    Formats double as a string using exponential notation (RRDTool like). Used for debugging through the project.
    
    Parameters:
    
    x - value to be formatted
    
    Returns:
    
    string like "+1.234567E+02"
  - getDate
```
public static Date getDate(long timestamp)
```
    Returns Date object for the given timestamp (in seconds, without milliseconds)
    
    Parameters:
    
    timestamp - Timestamp in seconds.
    
    Returns:
    
    Corresponding Date object.
  - getCalendar
```
public static Calendar getCalendar(long timestamp)
```
    Returns Calendar object for the given timestamp (in seconds, without milliseconds)
    
    Parameters:
    
    timestamp - Timestamp in seconds.
    
    Returns:
    
    Corresponding Calendar object.
  - getCalendar
```
public static Calendar getCalendar(Date date)
```
    Returns Calendar object for the given Date object
    
    Parameters:
    
    date - Date object
    
    Returns:
    
    Corresponding Calendar object.
  - getTimestamp
```
public static long getTimestamp(Date date)
```
    Returns timestamp (unix epoch) for the given Date object
    
    Parameters:
    
    date - Date object
    
    Returns:
    
    Corresponding timestamp (without milliseconds)
  - getTimestamp
```
public static long getTimestamp(Calendar gc)
```
    Returns timestamp (unix epoch) for the given Calendar object
    
    Parameters:
    
    gc - Calendar object
    
    Returns:
    
    Corresponding timestamp (without milliseconds)
  - getTimestamp
```
public static long getTimestamp(int year,
                                int month,
                                int day,
                                int hour,
                                int min)
```
    Returns timestamp (unix epoch) for the given year, month, day, hour and minute.
    
    Parameters:
    
    year - Year
    
    month - Month (zero-based)
    
    day - Day in month
    
    hour - Hour
    
    min - Minute
    
    Returns:
    
    Corresponding timestamp
  - getTimestamp
```
public static long getTimestamp(int year,
                                int month,
                                int day)
```
    Returns timestamp (unix epoch) for the given year, month and day.
    
    Parameters:
    
    year - Year
    
    month - Month (zero-based)
    
    day - Day in month
    
    Returns:
    
    Corresponding timestamp
  - getTimestamp
```
public static long getTimestamp(String atStyleTimeSpec)
```
    Parses at-style time specification and returns the corresponding timestamp. For example:
```
 long t = Util.getTimestamp("now-1d");
 
```
    Parameters:
    
    atStyleTimeSpec - at-style time specification. For the complete explanation of the syntax allowed see RRDTool's rrdfetch man page.
    
    Returns:
    
    timestamp in seconds since epoch.
  - getTimestamps
```
public static long[] getTimestamps(String atStyleTimeSpec1,
                                   String atStyleTimeSpec2)
```
    Parses two related at-style time specifications and returns corresponding timestamps. For example:
```
 long[] t = Util.getTimestamps("end-1d","now");
 
```
    Parameters:
    
    atStyleTimeSpec1 - Starting at-style time specification. For the complete explanation of the syntax allowed see RRDTool's rrdfetch man page.
    
    atStyleTimeSpec2 - Ending at-style time specification. For the complete explanation of the syntax allowed see RRDTool's rrdfetch man page.
    
    Returns:
    
    An array of two longs representing starting and ending timestamp in seconds since epoch.
  - parseDouble
```
public static double parseDouble(String valueStr)
```
    Parses input string as a double value. If the value cannot be parsed, Double.NaN is returned (NumberFormatException is never thrown).
    
    Parameters:
    
    valueStr - String representing double value
    
    Returns:
    
    a double corresponding to the input string
  - isDouble
```
public static boolean isDouble(String s)
```
    Checks if a string can be parsed as double.
    
    Parameters:
    
    s - Input string
    
    Returns:
    
    true if the string can be parsed as double, false otherwise
  - parseBoolean
```
public static boolean parseBoolean(String valueStr)
```
    Parses input string as a boolean value. The parser is case insensitive.
    
    Parameters:
    
    valueStr - String representing boolean value
    
    Returns:
    
    true, if valueStr equals to 'true', 'on', 'yes', 'y' or '1'; false in all other cases.
  - parseColor
```
public static Paint parseColor(String valueStr)
```
    Parses input string as color. The color string should be of the form #RRGGBB (no alpha specified, opaque color) or #RRGGBBAA (alpa specified, transparent colors). Leading character '#' is optional.
    
    Parameters:
    
    valueStr - Input string, for example #FFAA24, #AABBCC33, 010203 or ABC13E4F
    
    Returns:
    
    Paint object
    
    Throws:
    
    IllegalArgumentException - If the input string is not 6 or 8 characters long (without optional '#')
  - getFileSeparator
```
public static String getFileSeparator()
```
    Returns file system separator string.
    
    Returns:
    
    File system separator ("/" on Unix, "\" on Windows)
  - getUserHomeDirectory
```
public static String getUserHomeDirectory()
```
    Returns path to user's home directory.
    
    Returns:
    
    Path to users home directory, with file separator appended.
  - getRrd4jDemoDirectory
```
public static String getRrd4jDemoDirectory()
```
    Returns path to directory used for placement of Rrd4j demo graphs and creates it if necessary.
    
    Returns:
    
    Path to demo directory (defaults to $HOME/rrd4j/) if directory exists or was successfully created. Null if such directory could not be created.
  - getRrd4jDemoPath
```
public static String getRrd4jDemoPath(String filename)
```
    Returns full path to the file stored in the demo directory of Rrd4j
    
    Parameters:
    
    filename - Partial path to the file stored in the demo directory of Rrd4j (just name and extension, without parent directories)
    
    Returns:
    
    Full path to the file
  - getCalendar
```
public static Calendar getCalendar(String timeStr)
```
    Creates Calendar object from a string. The string should represent either a long integer (UNIX timestamp in seconds without milliseconds, like "1002354657") or a human readable date string in the format "yyyy-MM-dd HH:mm:ss" (like "2004-02-25 12:23:45").
    
    Parameters:
    
    timeStr - Input string
    
    Returns:
    
    Calendar object
  - getLapTime
```
public static String getLapTime()
```
    Function used for debugging purposes and performance bottlenecks detection. Probably of no use for end users of Rrd4j.
    
    Returns:
    
    String representing time in seconds since last getLapTime() method call.
  - getRrd4jHomeDirectory
```
public static String getRrd4jHomeDirectory()
```
    Returns the root directory of the Rrd4j distribution. Useful in some demo applications, probably of no use anywhere else.
    
    The function assumes that all Rrd4j .class files are placed under the <root>/classes subdirectory and that all jars (libraries) are placed in the <root>/lib subdirectory (the original Rrd4j directory structure).
    
    Returns:
    
    absolute path to Rrd4j's home directory
  - equal
```
public static boolean equal(double x,
                            double y)
```
    Compares two doubles but treats all NaNs as equal. In Java (by default) Double.NaN == Double.NaN always returns false
    
    Parameters:
    
    x - the first value
    
    y - the second value
    
    Returns:
    
    true if x and y are both equal to Double.NaN, or if x == y. false otherwise
  - getCanonicalPath
```
public static String getCanonicalPath(String path)
                               throws IOException
```
    Returns canonical file path for the given file path
    
    Parameters:
    
    path - Absolute or relative file path
    
    Returns:
    
    Canonical file path
    
    Throws:
    
    IOException - Thrown if canonical file path could not be resolved
  - getLastModified
```
public static long getLastModified(String file)
```
    Returns last modification time for the given file.
    
    Parameters:
    
    file - File object representing file on the disk
    
    Returns:
    
    Last modification time in seconds (without milliseconds)
  - fileExists
```
public static boolean fileExists(String filename)
```
    Checks if the file with the given file name exists
    
    Parameters:
    
    filename - File name
    
    Returns:
    
    true if file exists, false otherwise
  - max
```
public static double max(double[] values)
```
    Finds max value for an array of doubles (NaNs are ignored). If all values in the array are NaNs, NaN is returned.
    
    Parameters:
    
    values - Array of double values
    
    Returns:
    
    max value in the array (NaNs are ignored)
  - min
```
public static double min(double[] values)
```
    Finds min value for an array of doubles (NaNs are ignored). If all values in the array are NaNs, NaN is returned.
    
    Parameters:
    
    values - Array of double values
    
    Returns:
    
    min value in the array (NaNs are ignored)
  - sprintf
```
public static String sprintf(Locale l,
                             String format,
                             Object... args)
```
    Equivalent of the C-style sprintf function.
    
    Parameters:
    
    format - Format string
    
    args - Arbitrary list of arguments
    
    l - a Locale object.
    
    Returns:
    
    Formatted string

Class Util

Nested Class Summary

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

MAX_LONG

MIN_LONG

MAX_DOUBLE

MIN_DOUBLE

Method Detail

toDoubleArray

getTime

getTimestamp

normalize

max

min

sum

formatDouble

getDate

getCalendar

getCalendar

getTimestamp

getTimestamp

getTimestamp

getTimestamp

getTimestamp

getTimestamps

parseDouble

isDouble

parseBoolean

parseColor

getFileSeparator

getUserHomeDirectory

getRrd4jDemoDirectory

getRrd4jDemoPath

getCalendar

getLapTime

getRrd4jHomeDirectory

equal

getCanonicalPath

getLastModified

fileExists

max

min

sprintf