io.hektor.fsm

Class PreConditions

java.lang.Object

io.hektor.fsm.PreConditions

public final class PreConditions
extends Object

Contains common checks for null etc. All checkXXX will return a boolean and all ensureXXX will throw an IllegalArgumentException.

Author:

jonas@jonasborjesson.com

Method Summary

Modifier and Type	Method and Description
static boolean	checkIfEmpty(String string) Check if a string is empty, which includes null check.
static boolean	checkIfNotEmpty(String string)
static void	ensureArgument(boolean expression, String msg)
static String	ensureNotEmpty(String reference, String msg)
static <T> T	ensureNotNull(T reference)
static <T> T	ensureNotNull(T reference, String msg)
static <T> T	ifNull(T reference, T defaultValue) If our reference is null then return a default value instead.

Methods inherited from class java.lang.Object

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

Method Detail

ensureNotNull

public static <T> T ensureNotNull(T reference,
                                  String msg)
                           throws IllegalArgumentException

Throws:

IllegalArgumentException

ensureNotNull

public static <T> T ensureNotNull(T reference)
                           throws IllegalArgumentException

Throws:

IllegalArgumentException

checkIfEmpty

public static boolean checkIfEmpty(String string)

Check if a string is empty, which includes null check.

Parameters:

string -

Returns:

true if the string is either null or empty

checkIfNotEmpty

public static boolean checkIfNotEmpty(String string)

ensureNotEmpty

public static String ensureNotEmpty(String reference,
                                    String msg)
                             throws IllegalArgumentException

Throws:

IllegalArgumentException

ensureArgument

public static void ensureArgument(boolean expression,
                                  String msg)
                           throws IllegalArgumentException

Throws:

IllegalArgumentException

ifNull

public static <T> T ifNull(T reference,
                           T defaultValue)

If our reference is null then return a default value instead.

Parameters:

reference - the thing to check.

defaultValue - the default value to return if the above reference is null.

Returns:

the reference if not null, otherwise the default value. Note, if your default value is null as well then you will get back null, since that is what you asked. Chain with ensureNotNull(Object, String) if you want to make sure you have a non-null value for the default value.