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java.lang.Objectit.unimi.dsi.Util
public final class Util
All-purpose static-method container class.
Method Summary | |
---|---|
static long |
availableMemory()
Returns the amount of available memory (free memory plus never allocated memory). |
static void |
compactMemory()
Tries to compact memory as much as possible by forcing garbage collection. |
static void |
ensureLog4JIsConfigured()
Ensures that Log4J is configured, by invoking, if necessary, BasicConfigurator.configure() , and
setting the root logger level to Level.INFO . |
static void |
ensureLog4JIsConfigured(Class<?> klass)
Ensures that Log4J is configured, by invoking, if necessary, BasicConfigurator.configure() , and
setting the root logger level to Level.INFO . |
static void |
ensureLog4JIsConfigured(Class<?> klass,
Level level)
Ensures that Log4J is configured, by invoking, if necessary, BasicConfigurator.configure() , and
setting the root logger level to level . |
static void |
ensureLog4JIsConfigured(Level level)
Ensures that Log4J is configured, by invoking, if necessary, BasicConfigurator.configure() , and
setting the root logger level to a specified logging level. |
static String |
format(double d)
Formats a number. |
static String |
format(long l)
Formats a number. |
static String |
formatBinarySize(long l)
Formats a binary size. |
static String |
formatSize(long l)
Formats a size. |
static String |
formatSize2(long l)
Formats a size. |
static Logger |
getDebugLogger(Class<?> klass)
Calls Log4J's Logger.getLogger(java.lang.Class) method and then ensureLog4JIsConfigured() with argument Level.DEBUG . |
static Logger |
getLogger(Class<?> klass)
Calls Log4J's Logger.getLogger(java.lang.Class) method and then ensureLog4JIsConfigured() . |
static int[] |
identity(int n)
Stores the identity permutation in a new array of given length. |
static int[] |
identity(int[] perm)
Stores the identity permutation in an array. |
static long[][] |
identity(long n)
Stores the identity permutation in a new big array of given length. |
static long[][] |
identity(long[][] perm)
Stores the identity permutation in a big array. |
static int[] |
invertPermutation(int[] perm)
Computes the inverse of a permutation expressed as an array of n distinct integers in [0 .. n) and stores the result in a new array. |
static int[] |
invertPermutation(int[] perm,
int[] inv)
Computes the inverse of a permutation expressed as an array of n distinct integers in [0 .. n). |
static long[][] |
invertPermutation(long[][] perm)
Computes the inverse of a permutation expressed as a big array of n distinct long integers in [0 .. n) and stores the result in a new big array. |
static long[][] |
invertPermutation(long[][] perm,
long[][] inv)
Computes the inverse of a permutation expressed as a big array of n distinct long integers in [0 .. n). |
static int[] |
invertPermutationInPlace(int[] perm)
Computes in place the inverse of a permutation expressed as an array of n distinct integers in [0 .. n). |
static long[][] |
invertPermutationInPlace(long[][] perm)
Computes in place the inverse of a permutation expressed as a big array of n distinct long integers in [0 .. n). |
static boolean |
log4JIsConfigured()
Checks whether Log4J is properly configuring by searching for appenders in all loggers. |
static boolean |
memoryIsLow()
Returns true if less then 5% of the available memory is free. |
static int |
percAvailableMemory()
Returns the percentage of available memory (free memory plus never allocated memory). |
static long |
randomSeed()
Returns a random seed generated by calling System.nanoTime() , adding a unique identifier
and scrambling the result using
the finalisation step of Austin Appleby's
MurmurHash3. |
static byte[] |
randomSeedBytes()
Returns a random seed generated by calling System.nanoTime() , adding a unique identifier
and scrambling the result using
the finalisation step of Austin Appleby's MurmurHash3,
converted to a byte array. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Method Detail |
---|
public static String format(double d)
This method formats a double separating thousands and printing just two fractional digits.
d
- a number.
public static String format(long l)
This method formats a long separating thousands.
l
- a number.
public static String formatSize(long l)
This method formats a long using suitable unit multipliers (e.g., K, M, G, and T) and printing just two fractional digits.
l
- a number, representing a size (e.g., memory).
public static String formatBinarySize(long l)
This method formats a long using suitable unit binary multipliers (e.g., Ki, Mi, Gi, and Ti) and printing no fractional digits. The argument must be a power of 2.
l
- a number, representing a binary size (e.g., memory); must be a power of 2.
public static String formatSize2(long l)
This method formats a long using suitable binary unit multipliers (e.g., Ki, Mi, Gi, and Ti) and printing just two fractional digits.
l
- a number, representing a size (e.g., memory).
public static boolean log4JIsConfigured()
public static void ensureLog4JIsConfigured(Class<?> klass)
BasicConfigurator.configure()
, and
setting the root logger level to Level.INFO
.
klass
- the calling class (to be shown to the user).public static void ensureLog4JIsConfigured(Class<?> klass, Level level)
BasicConfigurator.configure()
, and
setting the root logger level to level
.
klass
- the calling class (to be shown to the user).level
- the required logging level.public static void ensureLog4JIsConfigured()
BasicConfigurator.configure()
, and
setting the root logger level to Level.INFO
.
public static void ensureLog4JIsConfigured(Level level)
BasicConfigurator.configure()
, and
setting the root logger level to a specified logging level.
level
- the required logging level.public static Logger getLogger(Class<?> klass)
Logger.getLogger(java.lang.Class)
method and then ensureLog4JIsConfigured()
.
klass
- a class that will be passed to Logger.getLogger(java.lang.Class)
.
Logger.getLogger(java.lang.Class)
.public static Logger getDebugLogger(Class<?> klass)
Logger.getLogger(java.lang.Class)
method and then ensureLog4JIsConfigured()
with argument Level.DEBUG
.
klass
- a class that will be passed to Logger.getLogger(java.lang.Class)
.
Logger.getLogger(java.lang.Class)
.public static boolean memoryIsLow()
public static long availableMemory()
public static int percAvailableMemory()
public static void compactMemory()
public static long randomSeed()
System.nanoTime()
, adding a unique identifier
and scrambling the result using
the finalisation step of Austin Appleby's
MurmurHash3.
public static byte[] randomSeedBytes()
System.nanoTime()
, adding a unique identifier
and scrambling the result using
the finalisation step of Austin Appleby's MurmurHash3,
converted to a byte array.
public static int[] invertPermutationInPlace(int[] perm)
Warning: if perm
is not a permutation,
essentially anything can happen.
perm
- the permutation to be inverted.
perm
.public static int[] invertPermutation(int[] perm, int[] inv)
Warning: if perm
is not a permutation,
essentially anything can happen.
perm
- the permutation to be inverted.inv
- the array storing the inverse.
inv
.public static int[] invertPermutation(int[] perm)
Warning: if perm
is not a permutation,
essentially anything can happen.
perm
- the permutation to be inverted.
public static int[] identity(int[] perm)
perm
- an array of integers.
perm
, filled with the identity permutation.public static int[] identity(int n)
n
- the size of the array.
n
, filled with the identity permutation.public static long[][] invertPermutationInPlace(long[][] perm)
Warning: if perm
is not a permutation,
essentially anything can happen.
perm
- the permutation to be inverted.
perm
.public static long[][] invertPermutation(long[][] perm, long[][] inv)
Warning: if perm
is not a permutation,
essentially anything can happen.
perm
- the permutation to be inverted.inv
- the big array storing the inverse.
inv
.public static long[][] invertPermutation(long[][] perm)
Warning: if perm
is not a permutation,
essentially anything can happen.
perm
- the permutation to be inverted.
public static long[][] identity(long[][] perm)
perm
- a big array.
perm
, filled with the identity permutation.public static long[][] identity(long n)
n
- the size of the array.
n
, filled with the identity permutation.
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