Class Preconditions

java.lang.Object

org.junit.platform.commons.util.Preconditions

@API(status=INTERNAL,
     since="1.0")
public final class Preconditions
extends Object

Collection of utilities for asserting preconditions for method and constructor arguments.

Each method in this class throws a PreconditionViolationException if the precondition is violated.

DISCLAIMER

These utilities are intended solely for usage within the JUnit framework itself. Any usage by external parties is not supported. Use at your own risk!

Since:

1.0

Method Summary

Modifier and Type	Method	Description
static void	condition(boolean predicate, String message)	Assert that the supplied predicate is true.
static void	condition(boolean predicate, Supplier<String> messageSupplier)	Assert that the supplied predicate is true.
static <T extends Collection<?>> @Nullable T	containsNoNullElements(@Nullable T collection, String message)	Assert that the supplied collection contains no null elements.
static <T extends Collection<?>> @Nullable T	containsNoNullElements(@Nullable T collection, Supplier<String> messageSupplier)	Assert that the supplied collection contains no null elements.
static <T> T @Nullable []	containsNoNullElements(T @Nullable [] array, String message)	Assert that the supplied array contains no null elements.
static <T> T @Nullable []	containsNoNullElements(T @Nullable [] array, Supplier<String> messageSupplier)	Assert that the supplied array contains no null elements.
static String	notBlank(@Nullable String str, String message)	Assert that the supplied String is not blank.
static String	notBlank(@Nullable String str, Supplier<String> messageSupplier)	Assert that the supplied String is not blank.
static int[]	notEmpty(int @Nullable [] array, String message)	Assert that the supplied array is neither null nor empty.
static <T extends Collection<?>> T	notEmpty(@Nullable T collection, String message)	Assert that the supplied Collection is neither null nor empty.
static <T extends Collection<?>> T	notEmpty(@Nullable T collection, Supplier<String> messageSupplier)	Assert that the supplied Collection is neither null nor empty.
static <T> T[]	notEmpty(T @Nullable [] array, String message)	Assert that the supplied array is neither null nor empty.
static <T> T[]	notEmpty(T @Nullable [] array, Supplier<String> messageSupplier)	Assert that the supplied array is neither null nor empty.
static <T> T	notNull(@Nullable T object, String message)	Assert that the supplied Object is not null.
static <T> T	notNull(@Nullable T object, Supplier<String> messageSupplier)	Assert that the supplied Object is not null.

Methods inherited from class java.lang.Object

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

Method Details

notNull

@Contract("null, _ -> fail; !null, _ -> param1")
public static <T> T notNull(@Nullable T object,
 String message)
                     throws PreconditionViolationException

Assert that the supplied Object is not null.

Parameters:

object - the object to check

message - precondition violation message

Returns:

the supplied object as a convenience

Throws:

PreconditionViolationException - if the supplied object is null

See Also:

• notNull(Object, Supplier)

notNull

@Contract("null, _ -> fail; !null, _ -> param1")
public static <T> T notNull(@Nullable T object,
 Supplier<String> messageSupplier)
                     throws PreconditionViolationException

Assert that the supplied Object is not null.

Parameters:

object - the object to check

messageSupplier - precondition violation message supplier

Returns:

the supplied object as a convenience

Throws:

PreconditionViolationException - if the supplied object is null

See Also:

• condition(boolean, Supplier)

notEmpty

@Contract("null, _ -> fail")
@API(status=INTERNAL,
     since="1.11")
public static int[] notEmpty(int @Nullable [] array,
 String message)
                      throws PreconditionViolationException

Assert that the supplied array is neither null nor empty.

Parameters:

array - the array to check

message - precondition violation message

Returns:

the supplied array as a convenience

Throws:

PreconditionViolationException - if the supplied array is null or empty

Since:

1.9

See Also:

• condition(boolean, String)

notEmpty

@Contract("null, _ -> fail")
public static <T> T[] notEmpty(T @Nullable [] array,
 String message)
                        throws PreconditionViolationException

Assert that the supplied array is neither null nor empty.

WARNING: this method does NOT check if the supplied array contains any null elements.

Parameters:

array - the array to check

message - precondition violation message

Returns:

the supplied array as a convenience

Throws:

PreconditionViolationException - if the supplied array is null or empty

See Also:

• containsNoNullElements(Object[], String)
• condition(boolean, String)

notEmpty

@Contract("null, _ -> fail")
public static <T> T[] notEmpty(T @Nullable [] array,
 Supplier<String> messageSupplier)
                        throws PreconditionViolationException

Assert that the supplied array is neither null nor empty.

WARNING: this method does NOT check if the supplied array contains any null elements.

Parameters:

array - the array to check

messageSupplier - precondition violation message supplier

Returns:

the supplied array as a convenience

Throws:

PreconditionViolationException - if the supplied array is null or empty

See Also:

• containsNoNullElements(Object[], String)
• condition(boolean, String)

notEmpty

@Contract("null, _ -> fail")
public static <T extends Collection<?>> T notEmpty(@Nullable T collection,
 String message)
                                            throws PreconditionViolationException

Assert that the supplied Collection is neither null nor empty.

WARNING: this method does NOT check if the supplied collection contains any null elements.

Parameters:

collection - the collection to check

message - precondition violation message

Returns:

the supplied collection as a convenience

Throws:

PreconditionViolationException - if the supplied collection is null or empty

See Also:

• containsNoNullElements(Collection, String)
• condition(boolean, String)

notEmpty

@Contract("null, _ -> fail")
public static <T extends Collection<?>> T notEmpty(@Nullable T collection,
 Supplier<String> messageSupplier)
                                            throws PreconditionViolationException

Assert that the supplied Collection is neither null nor empty.

WARNING: this method does NOT check if the supplied collection contains any null elements.

Parameters:

collection - the collection to check

messageSupplier - precondition violation message supplier

Returns:

the supplied collection as a convenience

Throws:

PreconditionViolationException - if the supplied collection is null or empty

See Also:

• containsNoNullElements(Collection, String)
• condition(boolean, String)

containsNoNullElements

@Contract("null, _ -> null")
public static <T> T @Nullable [] containsNoNullElements(T @Nullable [] array,
 String message)
                                                 throws PreconditionViolationException

Assert that the supplied array contains no null elements.

WARNING: this method does NOT check if the supplied array is null or empty.

Parameters:

array - the array to check

message - precondition violation message

Returns:

the supplied array as a convenience

Throws:

PreconditionViolationException - if the supplied array contains any null elements

See Also:

• notNull(Object, String)

containsNoNullElements

@Contract("null, _ -> null")
public static <T> T @Nullable [] containsNoNullElements(T @Nullable [] array,
 Supplier<String> messageSupplier)
                                                 throws PreconditionViolationException

Assert that the supplied array contains no null elements.

WARNING: this method does NOT check if the supplied array is null or empty.

Parameters:

array - the array to check

messageSupplier - precondition violation message supplier

Returns:

the supplied array as a convenience

Throws:

PreconditionViolationException - if the supplied array contains any null elements

See Also:

• notNull(Object, String)

containsNoNullElements

@Contract("null, _ -> null")
public static <T extends Collection<?>> @Nullable T containsNoNullElements(@Nullable T collection,
 String message)
                                                                    throws PreconditionViolationException

Assert that the supplied collection contains no null elements.

WARNING: this method does NOT check if the supplied collection is null or empty.

Parameters:

collection - the collection to check

message - precondition violation message

Returns:

the supplied collection as a convenience

Throws:

PreconditionViolationException - if the supplied collection contains any null elements

See Also:

• notNull(Object, String)

containsNoNullElements

@Contract("null, _ -> null")
public static <T extends Collection<?>> @Nullable T containsNoNullElements(@Nullable T collection,
 Supplier<String> messageSupplier)
                                                                    throws PreconditionViolationException

Assert that the supplied collection contains no null elements.

WARNING: this method does NOT check if the supplied collection is null or empty.

Parameters:

collection - the collection to check

messageSupplier - precondition violation message supplier

Returns:

the supplied collection as a convenience

Throws:

PreconditionViolationException - if the supplied collection contains any null elements

See Also:

• notNull(Object, String)

notBlank

@Contract("null, _ -> fail")
public static String notBlank(@Nullable String str,
 String message)
                       throws PreconditionViolationException

Assert that the supplied String is not blank.

A String is blank if it is null or consists only of whitespace characters.

Parameters:

str - the string to check

message - precondition violation message

Returns:

the supplied string as a convenience

Throws:

PreconditionViolationException - if the supplied string is blank

See Also:

• notBlank(String, Supplier)

notBlank

@Contract("null, _ -> fail")
public static String notBlank(@Nullable String str,
 Supplier<String> messageSupplier)
                       throws PreconditionViolationException

Assert that the supplied String is not blank.

A String is blank if it is null or consists only of whitespace characters.

Parameters:

str - the string to check

messageSupplier - precondition violation message supplier

Returns:

the supplied string as a convenience

Throws:

PreconditionViolationException - if the supplied string is blank

See Also:

• StringUtils.isNotBlank(String)
• condition(boolean, Supplier)

condition

@Contract("false, _ -> fail")
public static void condition(boolean predicate,
 String message)
                      throws PreconditionViolationException

Assert that the supplied predicate is true.

Parameters:

predicate - the predicate to check

message - precondition violation message

Throws:

PreconditionViolationException - if the predicate is false

See Also:

• condition(boolean, Supplier)

condition

@Contract("false, _ -> fail")
public static void condition(boolean predicate,
 Supplier<String> messageSupplier)
                      throws PreconditionViolationException

Assert that the supplied predicate is true.

Parameters:

predicate - the predicate to check

messageSupplier - precondition violation message supplier

Throws:

PreconditionViolationException - if the predicate is false