org.springframework.util

Class Assert

java.lang.Object

org.springframework.util.Assert

public abstract class Assert
extends Object

Assertion utility class that assists in validating arguments.

Useful for identifying programmer errors early and clearly at runtime.

For example, if the contract of a public method states it does not allow null arguments, Assert can be used to validate that contract. Doing this clearly indicates a contract violation when it occurs and protects the class's invariants.

Typically used to validate method arguments rather than configuration properties, to check for cases that are usually programmer errors rather than configuration errors. In contrast to configuration initialization code, there is usually no point in falling back to defaults in such methods.

This class is similar to JUnit's assertion library. If an argument value is deemed invalid, an IllegalArgumentException is thrown (typically). For example:

 Assert.notNull(clazz, "The class must not be null");
 Assert.isTrue(i > 0, "The value must be greater than zero");

Mainly for internal use within the framework; consider Apache's Commons Lang for a more comprehensive suite of String utilities.

Since:

1.1.2

Author:

Keith Donald, Juergen Hoeller, Sam Brannen, Colin Sampaleanu, Rob Harrop

Constructor Summary

Constructors

Constructor and Description
Assert()

Method Summary

Modifier and Type	Method and Description
static void	doesNotContain(String textToSearch, String substring) Deprecated. as of 4.3.7, in favor of doesNotContain(String, String, String)
static void	doesNotContain(String textToSearch, String substring, String message) Assert that the given text does not contain the given substring.
static void	doesNotContain(String textToSearch, String substring, Supplier<String> messageSupplier) Assert that the given text does not contain the given substring.
static void	hasLength(String text) Deprecated. as of 4.3.7, in favor of hasLength(String, String)
static void	hasLength(String text, String message) Assert that the given String is not empty; that is, it must not be null and not the empty String.
static void	hasLength(String text, Supplier<String> messageSupplier) Assert that the given String is not empty; that is, it must not be null and not the empty String.
static void	hasText(String text) Deprecated. as of 4.3.7, in favor of hasText(String, String)
static void	hasText(String text, String message) Assert that the given String contains valid text content; that is, it must not be null and must contain at least one non-whitespace character.
static void	hasText(String text, Supplier<String> messageSupplier) Assert that the given String contains valid text content; that is, it must not be null and must contain at least one non-whitespace character.
static void	isAssignable(Class<?> superType, Class<?> subType) Assert that superType.isAssignableFrom(subType) is true.
static void	isAssignable(Class<?> superType, Class<?> subType, String message) Assert that superType.isAssignableFrom(subType) is true.
static void	isAssignable(Class<?> superType, Class<?> subType, Supplier<String> messageSupplier) Assert that superType.isAssignableFrom(subType) is true.
static void	isInstanceOf(Class<?> type, Object obj) Assert that the provided object is an instance of the provided class.
static void	isInstanceOf(Class<?> type, Object obj, String message) Assert that the provided object is an instance of the provided class.
static void	isInstanceOf(Class<?> type, Object obj, Supplier<String> messageSupplier) Assert that the provided object is an instance of the provided class.
static void	isNull(Object object) Deprecated. as of 4.3.7, in favor of isNull(Object, String)
static void	isNull(Object object, String message) Assert that an object is null.
static void	isNull(Object object, Supplier<String> messageSupplier) Assert that an object is null.
static void	isTrue(boolean expression) Deprecated. as of 4.3.7, in favor of isTrue(boolean, String)
static void	isTrue(boolean expression, String message) Assert a boolean expression, throwing an IllegalArgumentException if the expression evaluates to false.
static void	isTrue(boolean expression, Supplier<String> messageSupplier) Assert a boolean expression, throwing an IllegalArgumentException if the expression evaluates to false.
static void	noNullElements(Object[] array) Deprecated. as of 4.3.7, in favor of noNullElements(Object[], String)
static void	noNullElements(Object[] array, String message) Assert that an array contains no null elements.
static void	noNullElements(Object[] array, Supplier<String> messageSupplier) Assert that an array contains no null elements.
static void	notEmpty(Collection<?> collection) Deprecated. as of 4.3.7, in favor of notEmpty(Collection, String)
static void	notEmpty(Collection<?> collection, String message) Assert that a collection contains elements; that is, it must not be null and must contain at least one element.
static void	notEmpty(Collection<?> collection, Supplier<String> messageSupplier) Assert that a collection contains elements; that is, it must not be null and must contain at least one element.
static void	notEmpty(Map<?,?> map) Deprecated. as of 4.3.7, in favor of notEmpty(Map, String)
static void	notEmpty(Map<?,?> map, String message) Assert that a Map contains entries; that is, it must not be null and must contain at least one entry.
static void	notEmpty(Map<?,?> map, Supplier<String> messageSupplier) Assert that a Map contains entries; that is, it must not be null and must contain at least one entry.
static void	notEmpty(Object[] array) Deprecated. as of 4.3.7, in favor of notEmpty(Object[], String)
static void	notEmpty(Object[] array, String message) Assert that an array contains elements; that is, it must not be null and must contain at least one element.
static void	notEmpty(Object[] array, Supplier<String> messageSupplier) Assert that an array contains elements; that is, it must not be null and must contain at least one element.
static void	notNull(Object object) Deprecated. as of 4.3.7, in favor of notNull(Object, String)
static void	notNull(Object object, String message) Assert that an object is not null.
static void	notNull(Object object, Supplier<String> messageSupplier) Assert that an object is not null.
static void	state(boolean expression) Deprecated. as of 4.3.7, in favor of state(boolean, String)
static void	state(boolean expression, String message) Assert a boolean expression, throwing an IllegalStateException if the expression evaluates to false.
static void	state(boolean expression, Supplier<String> messageSupplier) Assert a boolean expression, throwing an IllegalStateException if the expression evaluates to false.

Methods inherited from class java.lang.Object

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

Constructor Detail

Assert

public Assert()

Method Detail

state

public static void state(boolean expression,
                         String message)

Assert a boolean expression, throwing an IllegalStateException if the expression evaluates to false.

Call isTrue(boolean, java.lang.String) if you wish to throw an IllegalArgumentException on an assertion failure.

Assert.state(id == null, "The id property must not already be initialized");

Parameters:

expression - a boolean expression

message - the exception message to use if the assertion fails

Throws:

IllegalStateException - if expression is false

state

public static void state(boolean expression,
                         Supplier<String> messageSupplier)

Assert a boolean expression, throwing an IllegalStateException if the expression evaluates to false.

Call isTrue(boolean, java.lang.String) if you wish to throw an IllegalArgumentException on an assertion failure.

 Assert.state(entity.getId() == null,
     () -> "ID for entity " + entity.getName() + " must not already be initialized");
 

Parameters:

expression - a boolean expression

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalStateException - if expression is false

Since:

5.0

state

@Deprecated
public static void state(boolean expression)

Deprecated. as of 4.3.7, in favor of state(boolean, String)

Assert a boolean expression, throwing an IllegalStateException if the expression evaluates to false.

isTrue

public static void isTrue(boolean expression,
                          String message)

Assert a boolean expression, throwing an IllegalArgumentException if the expression evaluates to false.

Assert.isTrue(i > 0, "The value must be greater than zero");

Parameters:

expression - a boolean expression

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if expression is false

isTrue

public static void isTrue(boolean expression,
                          Supplier<String> messageSupplier)

Assert a boolean expression, throwing an IllegalArgumentException if the expression evaluates to false.

 Assert.isTrue(i > 0, () -> "The value '" + i + "' must be greater than zero");
 

Parameters:

expression - a boolean expression

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if expression is false

Since:

5.0

isTrue

@Deprecated
public static void isTrue(boolean expression)

Deprecated. as of 4.3.7, in favor of isTrue(boolean, String)

Assert a boolean expression, throwing an IllegalArgumentException if the expression evaluates to false.

isNull

public static void isNull(@Nullable
                          Object object,
                          String message)

Assert that an object is null.

Assert.isNull(value, "The value must be null");

Parameters:

object - the object to check

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the object is not null

isNull

public static void isNull(@Nullable
                          Object object,
                          Supplier<String> messageSupplier)

Assert that an object is null.

 Assert.isNull(value, () -> "The value '" + value + "' must be null");
 

Parameters:

object - the object to check

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the object is not null

Since:

5.0

isNull

@Deprecated
public static void isNull(@Nullable
                                      Object object)

Deprecated. as of 4.3.7, in favor of isNull(Object, String)

Assert that an object is null.

notNull

public static void notNull(@Nullable
                           Object object,
                           String message)

Assert that an object is not null.

Assert.notNull(clazz, "The class must not be null");

Parameters:

object - the object to check

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the object is null

notNull

public static void notNull(@Nullable
                           Object object,
                           Supplier<String> messageSupplier)

Assert that an object is not null.

 Assert.notNull(entity.getId(),
     () -> "ID for entity " + entity.getName() + " must not be null");
 

Parameters:

object - the object to check

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the object is null

Since:

5.0

notNull

@Deprecated
public static void notNull(@Nullable
                                       Object object)

Deprecated. as of 4.3.7, in favor of notNull(Object, String)

Assert that an object is not null.

hasLength

public static void hasLength(@Nullable
                             String text,
                             String message)

Assert that the given String is not empty; that is, it must not be null and not the empty String.

Assert.hasLength(name, "Name must not be empty");

Parameters:

text - the String to check

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the text is empty

See Also:

StringUtils.hasLength(java.lang.CharSequence)

hasLength

public static void hasLength(@Nullable
                             String text,
                             Supplier<String> messageSupplier)

Assert that the given String is not empty; that is, it must not be null and not the empty String.

 Assert.hasLength(account.getName(),
     () -> "Name for account '" + account.getId() + "' must not be empty");
 

Parameters:

text - the String to check

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the text is empty

Since:

5.0

See Also:

StringUtils.hasLength(java.lang.CharSequence)

hasLength

@Deprecated
public static void hasLength(@Nullable
                                         String text)

Deprecated. as of 4.3.7, in favor of hasLength(String, String)

Assert that the given String is not empty; that is, it must not be null and not the empty String.

hasText

public static void hasText(@Nullable
                           String text,
                           String message)

Assert that the given String contains valid text content; that is, it must not be null and must contain at least one non-whitespace character.

Assert.hasText(name, "'name' must not be empty");

Parameters:

text - the String to check

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the text does not contain valid text content

See Also:

StringUtils.hasText(java.lang.CharSequence)

hasText

public static void hasText(@Nullable
                           String text,
                           Supplier<String> messageSupplier)

Assert that the given String contains valid text content; that is, it must not be null and must contain at least one non-whitespace character.

 Assert.hasText(account.getName(),
     () -> "Name for account '" + account.getId() + "' must not be empty");
 

Parameters:

text - the String to check

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the text does not contain valid text content

Since:

5.0

See Also:

StringUtils.hasText(java.lang.CharSequence)

hasText

@Deprecated
public static void hasText(@Nullable
                                       String text)

Deprecated. as of 4.3.7, in favor of hasText(String, String)

Assert that the given String contains valid text content; that is, it must not be null and must contain at least one non-whitespace character.

doesNotContain

public static void doesNotContain(@Nullable
                                  String textToSearch,
                                  String substring,
                                  String message)

Assert that the given text does not contain the given substring.

Assert.doesNotContain(name, "rod", "Name must not contain 'rod'");

Parameters:

textToSearch - the text to search

substring - the substring to find within the text

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the text contains the substring

doesNotContain

public static void doesNotContain(@Nullable
                                  String textToSearch,
                                  String substring,
                                  Supplier<String> messageSupplier)

Assert that the given text does not contain the given substring.

 Assert.doesNotContain(name, forbidden, () -> "Name must not contain '" + forbidden + "'");
 

Parameters:

textToSearch - the text to search

substring - the substring to find within the text

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the text contains the substring

Since:

5.0

doesNotContain

@Deprecated
public static void doesNotContain(@Nullable
                                              String textToSearch,
                                              String substring)

Deprecated. as of 4.3.7, in favor of doesNotContain(String, String, String)

Assert that the given text does not contain the given substring.

notEmpty

public static void notEmpty(@Nullable
                            Object[] array,
                            String message)

Assert that an array contains elements; that is, it must not be null and must contain at least one element.

Assert.notEmpty(array, "The array must contain elements");

Parameters:

array - the array to check

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the object array is null or contains no elements

notEmpty

public static void notEmpty(@Nullable
                            Object[] array,
                            Supplier<String> messageSupplier)

Assert that an array contains elements; that is, it must not be null and must contain at least one element.

 Assert.notEmpty(array, () -> "The " + arrayType + " array must contain elements");
 

Parameters:

array - the array to check

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the object array is null or contains no elements

Since:

5.0

notEmpty

@Deprecated
public static void notEmpty(@Nullable
                                        Object[] array)

Deprecated. as of 4.3.7, in favor of notEmpty(Object[], String)

Assert that an array contains elements; that is, it must not be null and must contain at least one element.

noNullElements

public static void noNullElements(@Nullable
                                  Object[] array,
                                  String message)

Assert that an array contains no null elements.

Note: Does not complain if the array is empty!

Assert.noNullElements(array, "The array must contain non-null elements");

Parameters:

array - the array to check

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the object array contains a null element

noNullElements

public static void noNullElements(@Nullable
                                  Object[] array,
                                  Supplier<String> messageSupplier)

Assert that an array contains no null elements.

Note: Does not complain if the array is empty!

 Assert.noNullElements(array, () -> "The " + arrayType + " array must contain non-null elements");
 

Parameters:

array - the array to check

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the object array contains a null element

Since:

5.0

noNullElements

@Deprecated
public static void noNullElements(@Nullable
                                              Object[] array)

Deprecated. as of 4.3.7, in favor of noNullElements(Object[], String)

Assert that an array contains no null elements.

notEmpty

public static void notEmpty(@Nullable
                            Collection<?> collection,
                            String message)

Assert that a collection contains elements; that is, it must not be null and must contain at least one element.

Assert.notEmpty(collection, "Collection must contain elements");

Parameters:

collection - the collection to check

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the collection is null or contains no elements

notEmpty

public static void notEmpty(@Nullable
                            Collection<?> collection,
                            Supplier<String> messageSupplier)

Assert that a collection contains elements; that is, it must not be null and must contain at least one element.

 Assert.notEmpty(collection, () -> "The " + collectionType + " collection must contain elements");
 

Parameters:

collection - the collection to check

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the collection is null or contains no elements

Since:

5.0

notEmpty

@Deprecated
public static void notEmpty(@Nullable
                                        Collection<?> collection)

Deprecated. as of 4.3.7, in favor of notEmpty(Collection, String)

Assert that a collection contains elements; that is, it must not be null and must contain at least one element.

notEmpty

public static void notEmpty(@Nullable
                            Map<?,?> map,
                            String message)

Assert that a Map contains entries; that is, it must not be null and must contain at least one entry.

Assert.notEmpty(map, "Map must contain entries");

Parameters:

map - the map to check

message - the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the map is null or contains no entries

notEmpty

public static void notEmpty(@Nullable
                            Map<?,?> map,
                            Supplier<String> messageSupplier)

Assert that a Map contains entries; that is, it must not be null and must contain at least one entry.

 Assert.notEmpty(map, () -> "The " + mapType + " map must contain entries");
 

Parameters:

map - the map to check

messageSupplier - a supplier for the exception message to use if the assertion fails

Throws:

IllegalArgumentException - if the map is null or contains no entries

Since:

5.0

notEmpty

@Deprecated
public static void notEmpty(@Nullable
                                        Map<?,?> map)

Deprecated. as of 4.3.7, in favor of notEmpty(Map, String)

Assert that a Map contains entries; that is, it must not be null and must contain at least one entry.

isInstanceOf

public static void isInstanceOf(Class<?> type,
                                @Nullable
                                Object obj,
                                String message)

Assert that the provided object is an instance of the provided class.

Assert.instanceOf(Foo.class, foo, "Foo expected");

Parameters:

type - the type to check against

obj - the object to check

message - a message which will be prepended to provide further context. If it is empty or ends in ":" or ";" or "," or ".", a full exception message will be appended. If it ends in a space, the name of the offending object's type will be appended. In any other case, a ":" with a space and the name of the offending object's type will be appended.

Throws:

IllegalArgumentException - if the object is not an instance of type

isInstanceOf

public static void isInstanceOf(Class<?> type,
                                @Nullable
                                Object obj,
                                Supplier<String> messageSupplier)

Assert that the provided object is an instance of the provided class.

 Assert.instanceOf(Foo.class, foo, () -> "Processing " + Foo.class.getSimpleName() + ":");
 

Parameters:

type - the type to check against

obj - the object to check

messageSupplier - a supplier for the exception message to use if the assertion fails. See isInstanceOf(Class, Object, String) for details.

Throws:

IllegalArgumentException - if the object is not an instance of type

Since:

5.0

isInstanceOf

public static void isInstanceOf(Class<?> type,
                                @Nullable
                                Object obj)

Assert that the provided object is an instance of the provided class.

Assert.instanceOf(Foo.class, foo);

Parameters:

type - the type to check against

obj - the object to check

Throws:

IllegalArgumentException - if the object is not an instance of type

isAssignable

public static void isAssignable(Class<?> superType,
                                @Nullable
                                Class<?> subType,
                                String message)

Assert that superType.isAssignableFrom(subType) is true.

Assert.isAssignable(Number.class, myClass, "Number expected");

Parameters:

superType - the super type to check against

subType - the sub type to check

message - a message which will be prepended to provide further context. If it is empty or ends in ":" or ";" or "," or ".", a full exception message will be appended. If it ends in a space, the name of the offending sub type will be appended. In any other case, a ":" with a space and the name of the offending sub type will be appended.

Throws:

IllegalArgumentException - if the classes are not assignable

isAssignable

public static void isAssignable(Class<?> superType,
                                @Nullable
                                Class<?> subType,
                                Supplier<String> messageSupplier)

Assert that superType.isAssignableFrom(subType) is true.

 Assert.isAssignable(Number.class, myClass, () -> "Processing " + myAttributeName + ":");
 

Parameters:

superType - the super type to check against

subType - the sub type to check

messageSupplier - a supplier for the exception message to use if the assertion fails. See isAssignable(Class, Class, String) for details.

Throws:

IllegalArgumentException - if the classes are not assignable

Since:

5.0

isAssignable

public static void isAssignable(Class<?> superType,
                                Class<?> subType)

Assert that superType.isAssignableFrom(subType) is true.

Assert.isAssignable(Number.class, myClass);

Parameters:

superType - the super type to check

subType - the sub type to check

Throws:

IllegalArgumentException - if the classes are not assignable