Package com.blackrook.json.struct

Class Utils

java.lang.Object

com.blackrook.json.struct.Utils

public final class Utils
extends Object

A utility class.

Author:

Matthew Tropiano

Method Summary

Modifier and Type	Method	Description
static <T> T	construct(Constructor<T> constructor, Object... params)	Creates a new instance of a class from a class type.
static <T> T	create(Class<T> clazz)	Creates a new instance of a class from a class type.
static int	getArrayDimensions(Class<?> arrayType)	Gets how many dimensions that this array, represented by the provided type, has.
static int	getArrayDimensions(Object array)	Gets how many array dimensions that an object (presumably an array) has.
static Class<?>	getArrayType(Class<?> arrayType)	Gets the class type of this array type, if this is an array type.
static Class<?>	getArrayType(Object object)	Gets the class type of this array, if this is an array.
static <T extends Enum<T>> T	getEnumInstance(String value, Class<T> enumClass)	Returns the enum instance of a class given class and name, or null if not a valid name.
static Object	getFieldValue(Object instance, Field field)	Gets the value of a field on an object.
static Object	invokeBlind(Method method, Object instance, Object... params)	Blindly invokes a method, only throwing a RuntimeException if something goes wrong.
static boolean	isArray(Class<?> clazz)	Tests if a class is actually an array type.
static boolean	isArray(Object object)	Tests if an object is actually an array type.
static boolean	isEmpty(Object obj)	Checks if a value is "empty." The following is considered "empty": Null references.
static <T> T	isNull(T testObject, T nullReturn)	Returns the first object if it is not null, otherwise returns the second.
static boolean	parseBoolean(String s)	Attempts to parse a boolean from a string.
static boolean	parseBoolean(String s, boolean def)	Attempts to parse a boolean from a string.
static byte	parseByte(String s)	Attempts to parse a byte from a string.
static byte	parseByte(String s, byte def)	Attempts to parse a byte from a string.
static char	parseChar(String s)	Attempts to parse a char from a string.
static char	parseChar(String s, char def)	Attempts to parse a byte from a string.
static double	parseDouble(String s)	Attempts to parse a double from a string.
static double	parseDouble(String s, double def)	Attempts to parse a double from a string.
static float	parseFloat(String s)	Attempts to parse a float from a string.
static float	parseFloat(String s, float def)	Attempts to parse a float from a string.
static int	parseInt(String s)	Attempts to parse an int from a string.
static int	parseInt(String s, int def)	Attempts to parse an int from a string.
static long	parseLong(String s)	Attempts to parse a long from a string.
static long	parseLong(String s, long def)	Attempts to parse a long from a string.
static short	parseShort(String s)	Attempts to parse a short from a string.
static short	parseShort(String s, short def)	Attempts to parse a short from a string.
static void	setFieldValue(Object instance, Field field, Object value)	Sets the value of a field on an object.

Methods inherited from class java.lang.Object

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

Method Details

isNull

public static <T> T isNull(T testObject,
 T nullReturn)

Returns the first object if it is not null, otherwise returns the second.

Type Parameters:

T - class that extends Object.

Parameters:

testObject - the first ("tested") object.

nullReturn - the object to return if testObject is null.

Returns:

testObject if not null, nullReturn otherwise.

setFieldValue

public static void setFieldValue(Object instance,
 Field field,
 Object value)

Sets the value of a field on an object.

Parameters:

instance - the object instance to set the field on.

field - the field to set.

value - the value to set.

Throws:

NullPointerException - if the field or object provided is null.

ClassCastException - if the value could not be cast to the proper type.

RuntimeException - if anything goes wrong (bad field name, bad target, bad argument, or can't access the field).

See Also:

• Field.set(Object, Object)

getFieldValue

public static Object getFieldValue(Object instance,
 Field field)

Gets the value of a field on an object.

Parameters:

instance - the object instance to get the field value of.

field - the field to get the value of.

Returns:

the current value of the field.

Throws:

NullPointerException - if the field or object provided is null.

RuntimeException - if anything goes wrong (bad target, bad argument, or can't access the field).

See Also:

• Field.set(Object, Object)

invokeBlind

public static Object invokeBlind(Method method,
 Object instance,
 Object... params)

Blindly invokes a method, only throwing a RuntimeException if something goes wrong. Here for the convenience of not making a billion try/catch clauses for a method invocation.

Parameters:

method - the method to invoke.

instance - the object instance that is the method target.

params - the parameters to pass to the method.

Returns:

the return value from the method invocation. If void, this is null.

Throws:

ClassCastException - if one of the parameters could not be cast to the proper type.

RuntimeException - if anything goes wrong (bad target, bad argument, or can't access the method).

See Also:

• Method.invoke(Object, Object...)

isEmpty

public static boolean isEmpty(Object obj)

Checks if a value is "empty." The following is considered "empty":

• Null references.
• Array objects that have a length of 0.
• Boolean objects that are false.
• Character objects that are the null character ('\0', '').
• Number objects that are zero.
• String objects that are the empty string, or are String.trim()'ed down to the empty string.
• Collection objects where Collection.isEmpty() returns true.

Parameters:

obj - the object to check.

Returns:

true if the provided object is considered "empty", false otherwise.

isArray

public static boolean isArray(Class<?> clazz)

Tests if a class is actually an array type.

Parameters:

clazz - the class to test.

Returns:

true if so, false if not.

isArray

public static boolean isArray(Object object)

Tests if an object is actually an array type.

Parameters:

object - the object to test.

Returns:

true if so, false if not.

getArrayDimensions

public static int getArrayDimensions(Class<?> arrayType)

Gets how many dimensions that this array, represented by the provided type, has.

Parameters:

arrayType - the type to inspect.

Returns:

the number of array dimensions, or 0 if not an array.

getArrayDimensions

public static int getArrayDimensions(Object array)

Gets how many array dimensions that an object (presumably an array) has.

Parameters:

array - the object to inspect.

Returns:

the number of array dimensions, or 0 if not an array.

getArrayType

public static Class<?> getArrayType(Class<?> arrayType)

Gets the class type of this array type, if this is an array type.

Parameters:

arrayType - the type to inspect.

Returns:

this array's type, or null if the provided type is not an array, or if the found class is not on the classpath.

getArrayType

public static Class<?> getArrayType(Object object)

Gets the class type of this array, if this is an array.

Parameters:

object - the object to inspect.

Returns:

this array's type, or null if the provided object is not an array, or if the found class is not on the classpath.

create

public static <T> T create(Class<T> clazz)

Creates a new instance of a class from a class type. This essentially calls Class.newInstance(), but wraps the call in a try/catch block that only throws an exception if something goes wrong.

Type Parameters:

T - the return object type.

Parameters:

clazz - the class type to instantiate.

Returns:

a new instance of an object.

Throws:

RuntimeException - if instantiation cannot happen, either due to a non-existent constructor or a non-visible constructor.

construct

public static <T> T construct(Constructor<T> constructor,
 Object... params)

Creates a new instance of a class from a class type. This essentially calls Class.newInstance(), but wraps the call in a try/catch block that only throws an exception if something goes wrong.

Type Parameters:

T - the return object type.

Parameters:

constructor - the constructor to call.

params - the constructor parameters.

Returns:

a new instance of an object created via the provided constructor.

Throws:

RuntimeException - if instantiation cannot happen, either due to a non-existent constructor or a non-visible constructor.

getEnumInstance

public static <T extends Enum<T>> T getEnumInstance(String value,
 Class<T> enumClass)

Returns the enum instance of a class given class and name, or null if not a valid name. If value is null, this returns null.

Type Parameters:

T - the Enum object type.

Parameters:

value - the value to search for.

enumClass - the Enum class to inspect.

Returns:

the enum value or null if the target does not exist.

parseBoolean

public static boolean parseBoolean(String s)

Attempts to parse a boolean from a string. If the string is null, this returns false. If the string does not equal "true" (case ignored), this returns false.

Parameters:

s - the input string.

Returns:

the interpreted boolean.

parseByte

public static byte parseByte(String s)

Attempts to parse a byte from a string. If the string is null or the empty string, this returns 0.

Parameters:

s - the input string.

Returns:

the interpreted byte.

parseShort

public static short parseShort(String s)

Attempts to parse a short from a string. If the string is null or the empty string, this returns 0.

Parameters:

s - the input string.

Returns:

the interpreted short.

parseChar

public static char parseChar(String s)

Attempts to parse a char from a string. If the string is null or the empty string, this returns '\0'.

Parameters:

s - the input string.

Returns:

the first character in the string.

parseInt

public static int parseInt(String s)

Attempts to parse an int from a string. If the string is null or the empty string, this returns 0.

Parameters:

s - the input string.

Returns:

the interpreted integer.

parseLong

public static long parseLong(String s)

Attempts to parse a long from a string. If the string is null or the empty string, this returns 0.

Parameters:

s - the input string.

Returns:

the interpreted long integer.

parseFloat

public static float parseFloat(String s)

Attempts to parse a float from a string. If the string is null or the empty string, this returns 0.0f.

Parameters:

s - the input string.

Returns:

the interpreted float.

parseDouble

public static double parseDouble(String s)

Attempts to parse a double from a string. If the string is null or the empty string, this returns 0.0.

Parameters:

s - the input string.

Returns:

the interpreted double.

parseBoolean

public static boolean parseBoolean(String s,
 boolean def)

Attempts to parse a boolean from a string. If the string is null or the empty string, this returns def. If the string does not equal "true," this returns false.

Parameters:

s - the input string.

def - the fallback value to return.

Returns:

the interpreted boolean or def if the input string is blank.

parseByte

public static byte parseByte(String s,
 byte def)

Attempts to parse a byte from a string. If the string is null or the empty string, this returns def.

Parameters:

s - the input string.

def - the fallback value to return.

Returns:

the interpreted byte or def if the input string is blank.

parseShort

public static short parseShort(String s,
 short def)

Attempts to parse a short from a string. If the string is null or the empty string, this returns def.

Parameters:

s - the input string.

def - the fallback value to return.

Returns:

the interpreted short or def if the input string is blank.

parseChar

public static char parseChar(String s,
 char def)

Attempts to parse a byte from a string. If the string is null or the empty string, this returns def.

Parameters:

s - the input string.

def - the fallback value to return.

Returns:

the first character in the string or def if the input string is blank.

parseInt

public static int parseInt(String s,
 int def)

Attempts to parse an int from a string. If the string is null or the empty string, this returns def.

Parameters:

s - the input string.

def - the fallback value to return.

Returns:

the interpreted integer or def if the input string is blank.

parseLong

public static long parseLong(String s,
 long def)

Attempts to parse a long from a string. If the string is null or the empty string, this returns def.

Parameters:

s - the input string.

def - the fallback value to return.

Returns:

the interpreted long integer or def if the input string is blank.

parseFloat

public static float parseFloat(String s,
 float def)

Attempts to parse a float from a string. If the string is null or the empty string, this returns def.

Parameters:

s - the input string.

def - the fallback value to return.

Returns:

the interpreted float or def if the input string is blank.

parseDouble

public static double parseDouble(String s,
 double def)

Attempts to parse a double from a string. If the string is null or the empty string, this returns def.

Parameters:

s - the input string.

def - the fallback value to return.

Returns:

the interpreted double or def if the input string is blank.