org.jminor.common

Class Util

java.lang.Object

org.jminor.common.Util

public final class Util
extends java.lang.Object

Misc. utilities.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Util.MapKeyProvider<K,V> Provides objects of type K, derived from a value of type V, for hashing said value via .hashCode().
static interface	Util.PropertyWriter Writes a property value

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	FILE_SEPARATOR The file separator for the current system
static java.lang.String	LINE_SEPARATOR The line separator for the current system
static java.lang.String	PATH_SEPARATOR The path separator for the current system

Method Summary

Modifier and Type	Method and Description
static void	closeSilently(java.io.Closeable... closeables) Closes the given Closeable instances, swallowing any Exceptions that occur
static <T> T	deserialize(byte[] bytes) Deserializes the given byte array into a T, null or an empty byte array result in a null return value
static long	getAllocatedMemory()
static long	getFreeMemory()
static java.lang.reflect.Method	getGetMethod(java.lang.Class valueType, java.lang.String property, java.lang.Class ownerClass)
static java.lang.reflect.Method	getGetMethod(java.lang.Class valueType, java.lang.String property, java.lang.Object valueOwner)
static long	getMaxMemory()
static java.lang.String	getMemoryUsageString()
static java.lang.reflect.Method	getSetMethod(java.lang.Class valueType, java.lang.String property, java.lang.Class ownerClass)
static java.lang.reflect.Method	getSetMethod(java.lang.Class valueType, java.lang.String property, java.lang.Object valueOwner)
static java.lang.String	getSystemProperties()
static java.lang.String	getSystemProperties(Util.PropertyWriter propertyWriter)
static long	getUsedMemory()
static <T> T	initializeProxy(java.lang.Class<T> clazz, java.lang.reflect.InvocationHandler invocationHandler) Initializes a proxy instance for the given class, using the class loader of that class
static <K,V> java.util.LinkedHashMap<K,java.util.List<V>>	map(java.util.Collection<V> values, Util.MapKeyProvider<K,V> keyProvider) Maps the given values according to the keys provided by the given key provider, keeping the iteration order of the given collection.
static boolean	notNull(java.lang.Object... objects) Checks if any of the given objects is null
static boolean	nullOrEmpty(java.util.Collection... collections)
static boolean	nullOrEmpty(java.util.Collection collection)
static boolean	nullOrEmpty(java.util.Map... maps)
static boolean	nullOrEmpty(java.util.Map map)
static boolean	nullOrEmpty(java.lang.String... strings)
static boolean	onClasspath(java.lang.String className)
static java.lang.String	rejectNullOrEmpty(java.lang.String value, java.lang.String valueName) Throws an IllegalArgumentException if the given string value is null or empty
static double	roundDouble(double d, int places) Rounds the given double to places decimal places
static byte[]	serialize(java.lang.Object object) Serializes the given Object, null object results in an empty byte array

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LINE_SEPARATOR

public static final java.lang.String LINE_SEPARATOR

The line separator for the current system

FILE_SEPARATOR

public static final java.lang.String FILE_SEPARATOR

The file separator for the current system

PATH_SEPARATOR

public static final java.lang.String PATH_SEPARATOR

The path separator for the current system

Method Detail

nullOrEmpty

public static boolean nullOrEmpty(java.lang.String... strings)

Parameters:

strings - the strings to check

Returns:

true if one of the given strings is null or empty or if no arguments are provided, false otherwise

notNull

public static boolean notNull(java.lang.Object... objects)

Checks if any of the given objects is null

Parameters:

objects - the objects to check

Returns:

true if none of the given objects is null

map

public static <K,V> java.util.LinkedHashMap<K,java.util.List<V>> map(java.util.Collection<V> values,
                                                                     Util.MapKeyProvider<K,V> keyProvider)

Maps the given values according to the keys provided by the given key provider, keeping the iteration order of the given collection. class Person { String name; Integer age; ... } List<Person> persons = ...; MapKeyProvider ageKeyProvider = new MapKeyProvider<Integer, Person>() { public Integer getKey(Person person) { return person.getAge(); } }; Map<Integer, List<Person>> personsByAge = Util.map(persons, ageKeyProvider);

Type Parameters:

K - the key type

V - the value type

Parameters:

values - the values to map

keyProvider - the object providing keys for values

Returns:

a LinkedHashMap with the values mapped to their respective key values, respecting the iteration order of the given collection

onClasspath

public static boolean onClasspath(java.lang.String className)

Parameters:

className - the name of the class to search for

Returns:

true if the given class is found on the classpath

nullOrEmpty

public static boolean nullOrEmpty(java.util.Map... maps)

Parameters:

maps - the maps to check

Returns:

true if one of the given maps is null or empty or if no arguments are provided, false otherwise

nullOrEmpty

public static boolean nullOrEmpty(java.util.Map map)

Parameters:

map - the map to check

Returns:

true if the given map is null or empty, false otherwise

nullOrEmpty

public static boolean nullOrEmpty(java.util.Collection... collections)

Parameters:

collections - the collections to check

Returns:

true if one of the given collections is null or empty or if no arguments are provided, false otherwise

nullOrEmpty

public static boolean nullOrEmpty(java.util.Collection collection)

Parameters:

collection - the collection to check

Returns:

true if the given collection is null or empty, false otherwise

rejectNullOrEmpty

public static java.lang.String rejectNullOrEmpty(java.lang.String value,
                                                 java.lang.String valueName)

Throws an IllegalArgumentException if the given string value is null or empty

Parameters:

value - the string value

valueName - the name of the value to include in the error message

Returns:

the string value

roundDouble

public static double roundDouble(double d,
                                 int places)

Rounds the given double to places decimal places

Parameters:

d - the double to round

places - the number of decimal places

Returns:

the rounded value

closeSilently

public static void closeSilently(java.io.Closeable... closeables)

Closes the given Closeable instances, swallowing any Exceptions that occur

Parameters:

closeables - the closeables to close

getSystemProperties

public static java.lang.String getSystemProperties()

Returns:

a String containing all system properties, one per line

getSystemProperties

public static java.lang.String getSystemProperties(Util.PropertyWriter propertyWriter)

Parameters:

propertyWriter - for specific property formatting or exclusions

Returns:

a String containing all system properties, one per line

initializeProxy

public static <T> T initializeProxy(java.lang.Class<T> clazz,
                                    java.lang.reflect.InvocationHandler invocationHandler)

Initializes a proxy instance for the given class, using the class loader of that class

Type Parameters:

T - the type

Parameters:

clazz - the class to proxy

invocationHandler - the invocation handler to use

Returns:

a proxy for the given class

serialize

public static byte[] serialize(java.lang.Object object)
                        throws java.io.IOException

Serializes the given Object, null object results in an empty byte array

Parameters:

object - the object

Returns:

a byte array representing the serialized object, an empty byte array in case of null

Throws:

java.io.IOException - in case of an exception

deserialize

public static <T> T deserialize(byte[] bytes)
                         throws java.io.IOException,
                                java.lang.ClassNotFoundException

Deserializes the given byte array into a T, null or an empty byte array result in a null return value

Type Parameters:

T - the type of the object represented in the byte array

Parameters:

bytes - a byte array representing the serialized object

Returns:

the deserialized object

Throws:

java.io.IOException - in case of an exception

java.lang.ClassNotFoundException - in case the deserialized class is not found

getAllocatedMemory

public static long getAllocatedMemory()

Returns:

the total memory allocated by this JVM in kilobytes

getFreeMemory

public static long getFreeMemory()

Returns:

the free memory available to this JVM in kilobytes

getMaxMemory

public static long getMaxMemory()

Returns:

the maximum memory available to this JVM in kilobytes

getUsedMemory

public static long getUsedMemory()

Returns:

the memory used by this JVM in kilobytes

getMemoryUsageString

public static java.lang.String getMemoryUsageString()

Returns:

a String indicating the memory usage of this JVM

getSetMethod

public static java.lang.reflect.Method getSetMethod(java.lang.Class valueType,
                                                    java.lang.String property,
                                                    java.lang.Object valueOwner)
                                             throws java.lang.NoSuchMethodException

Parameters:

valueType - the class of the value for the given property

property - the name of the property for which to retrieve the set method

valueOwner - an instance

Returns:

the method used to set the value of the linked property

Throws:

java.lang.NoSuchMethodException - if the method does not exist in the owner class

getSetMethod

public static java.lang.reflect.Method getSetMethod(java.lang.Class valueType,
                                                    java.lang.String property,
                                                    java.lang.Class ownerClass)
                                             throws java.lang.NoSuchMethodException

Parameters:

valueType - the class of the value for the given property

property - the name of the property for which to retrieve the set method

ownerClass - the class

Returns:

the method used to set the value of the linked property

Throws:

java.lang.NoSuchMethodException - if the method does not exist in the owner class

getGetMethod

public static java.lang.reflect.Method getGetMethod(java.lang.Class valueType,
                                                    java.lang.String property,
                                                    java.lang.Object valueOwner)
                                             throws java.lang.NoSuchMethodException

Parameters:

valueType - the class of the value for the given property

property - the name of the property for which to retrieve the get method

valueOwner - an instance

Returns:

the method used to get the value of the linked property

Throws:

java.lang.NoSuchMethodException - if the method does not exist in the owner class

getGetMethod

public static java.lang.reflect.Method getGetMethod(java.lang.Class valueType,
                                                    java.lang.String property,
                                                    java.lang.Class ownerClass)
                                             throws java.lang.NoSuchMethodException

Parameters:

valueType - the class of the value for the given property

property - the name of the property for which to retrieve the get method

ownerClass - the class

Returns:

the method used to get the value of the linked property

Throws:

java.lang.NoSuchMethodException - if the method does not exist in the owner class