Util (ff4j-core 1.6.3 API)

java.lang.Object
- org.ff4j.utils.Util

```
public class Util
extends Object
```
Tips and tricks to be less verbose.

Author:

Cedrick Lunven (@clunven)

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <T> Collection<T>`	`asCollection(Object ob)` Downcast as collection or return error.
`static void`	`assertEvent(Event evt)`
`static void`	`assertHasLength(String... params)` Check that string is not null
`static void`	`assertNotEmpty(Collection<?> collec)` Check that string is not null
`static void`	`assertNotNull(Object... params)` Check that object is not null.
`static void`	`assertNotNull(String objectName, Object... params)` Check that object is not null.
`static void`	`assertNull(Object object)` Check that object is null.
`static void`	`assertParamHasLength(String param, String paramName)` Parameter validation.
`static void`	`assertParamHasNotNull(Object param, String paramName)` Parameter validation.
`static void`	`assertTrue(boolean expression)` Check that expression is true.
`static List<String>`	`generateHSVGradient(String codeFrom, String codeTo, int nbDivision)`
`static List<String>`	`generateRGBGradient(String codeFrom, String codeTo, int nbDivision)` This code build the color gradient between 2 colors with defined step.
`static List<String>`	`getColorsGradient(int nbsectors)` Dedicated gradient for ff4j console (Pie Chart).
`static <T,E> T`	`getFirstKeyByValue(Map<T,E> map, E value)` Get a first key matching from value.
`static <T,E> Set<T>`	`getKeysByValue(Map<T,E> map, E value)` Get key listfrom value.
`static <T> T`	`getRandomElement(List<T> myList)` Get a random element from a list.
`static int`	`getRandomOffset(int size)` Get a random offset within map.
`static boolean`	`hasLength(String expression)` Check that expression is true.
`static <T> T`	`instanciatePrivate(Class<T> utilityClass)` Allow to instanciate utility class.
`static boolean`	`isClassCollection(Class<?> c)` Check if a current class can be cast to collection.
`static boolean`	`isCollection(Object ob)` Check if a current object can be cast to collection.
`static boolean`	`isEmpty(Collection<?> ob)` Check if a current object is empty
`static boolean`	`isValidClass(Class<?> clazz)` Check that class is valid.
`static <T> String`	`join(Collection<T> collec, String delimiter)` Serialize collection elements with a delimiter.
`static <T> List<T>`	`list(T... els)` Create an HashSet.
`static <T> Set<T>`	`set(T... els)` Create an HashSet.

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

- Method Detail
  - hasLength
```
public static boolean hasLength(String expression)
```
    Check that expression is true.
    
    Parameters:
    
    expression - expression to evaluate
  - isValidClass
```
public static boolean isValidClass(Class<?> clazz)
```
    Check that class is valid.
    
    Parameters:
    
    expression - expression to evaluate
  - assertTrue
```
public static void assertTrue(boolean expression)
```
    Check that expression is true.
    
    Parameters:
    
    expression - expression to evaluate
  - assertNull
```
public static void assertNull(Object object)
```
    Check that object is null.
    
    Parameters:
    
    object - target object
  - assertEvent
```
public static void assertEvent(Event evt)
```
  - assertNotNull
```
public static void assertNotNull(Object... params)
```
    Check that object is not null.
    
    Parameters:
    
    object - target object
  - assertNotNull
```
public static void assertNotNull(String objectName,
                                 Object... params)
```
    Check that object is not null.
    
    Parameters:
    
    object - target object
  - assertHasLength
```
public static void assertHasLength(String... params)
```
    Check that string is not null
    
    Parameters:
    
    object - target object
  - assertNotEmpty
```
public static void assertNotEmpty(Collection<?> collec)
```
    Check that string is not null
    
    Parameters:
    
    object - target object
  - assertParamHasLength
```
public static void assertParamHasLength(String param,
                                        String paramName)
```
    Parameter validation.
    
    Parameters:
    
    param - current parameter
    
    paramName - current parameter name
  - assertParamHasNotNull
```
public static void assertParamHasNotNull(Object param,
                                         String paramName)
```
    Parameter validation.
    
    Parameters:
    
    param - current parameter
    
    paramName - current parameter name
  - set
```
public static <T> Set<T> set(T... els)
```
    Create an HashSet.
    
    Parameters:
    
    els - enumeration of elements
    
    Returns:
  - list
```
public static <T> List<T> list(T... els)
```
    Create an HashSet.
    
    Parameters:
    
    els - enumeration of elements
    
    Returns:
  - join
```
public static <T> String join(Collection<T> collec,
                              String delimiter)
```
    Serialize collection elements with a delimiter.
    
    Parameters:
    
    collec - collection (a,b,c)
    
    delimiter - delimiter char (e.g : ",")
    
    Returns:
    
    the list : a,b,c
  - isClassCollection
```
public static boolean isClassCollection(Class<?> c)
```
    Check if a current class can be cast to collection.
    
    Parameters:
    
    c - current class
    
    Returns:
    
    flag if it's a collection
  - isCollection
```
public static boolean isCollection(Object ob)
```
    Check if a current object can be cast to collection.
    
    Parameters:
    
    ob - current object
    
    Returns:
    
    flag if it's a collection
  - isEmpty
```
public static boolean isEmpty(Collection<?> ob)
```
    Check if a current object is empty
    
    Parameters:
    
    ob - current collection
    
    Returns:
    
    flag if it's an empty collection
  - asCollection
```
public static <T> Collection<T> asCollection(Object ob)
```
    Downcast as collection or return error.
    
    Parameters:
    
    ob - target object
    
    Returns:
    
    if can ve converted to collection.
  - getRandomOffset
```
public static int getRandomOffset(int size)
```
    Get a random offset within map.
    
    Parameters:
    
    size - target list size
    
    Returns:
    
    a random positive integer below size
  - getRandomElement
```
public static <T> T getRandomElement(List<T> myList)
```
    Get a random element from a list.
    
    Parameters:
    
    myList - current list
  - generateRGBGradient
```
public static List<String> generateRGBGradient(String codeFrom,
                                               String codeTo,
                                               int nbDivision)
```
    This code build the color gradient between 2 colors with defined step.
    
    Parameters:
    
    codeFrom - color source
    
    codeTo - color destination
    
    nbDivision - number of steps
    
    Returns:
    
    the list of colors
  - generateHSVGradient
```
public static List<String> generateHSVGradient(String codeFrom,
                                               String codeTo,
                                               int nbDivision)
```
  - getColorsGradient
```
public static List<String> getColorsGradient(int nbsectors)
```
    Dedicated gradient for ff4j console (Pie Chart).
    
    Parameters:
    
    nbsectors - target sectors
    
    Returns:
    
    color gradient
  - instanciatePrivate
```
public static <T> T instanciatePrivate(Class<T> utilityClass)
                                throws Exception
```
    Allow to instanciate utility class.
    
    Parameters:
    
    utilityClass - current utility
    
    Returns:
    
    instance
    
    Throws:
    
    Exception
  - getKeysByValue
```
public static <T,E> Set<T> getKeysByValue(Map<T,E> map,
                                          E value)
```
    Get key listfrom value.
    
    Parameters:
    
    map - current MAP
    
    value - value of MAP
    
    Returns:
  - getFirstKeyByValue
```
public static <T,E> T getFirstKeyByValue(Map<T,E> map,
                                         E value)
```
    Get a first key matching from value.
    
    Parameters:
    
    map - current MAP
    
    value - value of MAP
    
    Returns:

Class Util

Method Summary

Methods inherited from class java.lang.Object

Method Detail

hasLength

isValidClass

assertTrue

assertNull

assertEvent

assertNotNull

assertNotNull

assertHasLength

assertNotEmpty

assertParamHasLength

assertParamHasNotNull

set

list

join

isClassCollection

isCollection

isEmpty

asCollection

getRandomOffset

getRandomElement

generateRGBGradient

generateHSVGradient

getColorsGradient

instanciatePrivate

getKeysByValue

getFirstKeyByValue