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; for a more comprehensive suite of assertion utilities consider org.apache.commons.lang3.Validate from Apache Commons Lang, Google Guava's Preconditions, or similar third-party libraries.
Since:
1.1.2
Author:
Keith Donald, Juergen Hoeller, Sam Brannen, Colin Sampaleanu, Rob Harrop

Constructor Summary
Constructors
Constructor Description
Assert()

Method Summary

All Methods Static Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	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`	`noNullElements(Collection<?> collection, String message)`	Assert that a collection contains no `null` elements.
`static void`	`noNullElements(Collection<?> collection, Supplier<String> messageSupplier)`	Assert that a collection contains no `null` elements.
`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`	`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`	`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.
  - noNullElements
```
public static void noNullElements(@Nullable
                                  Collection<?> collection,
                                  String message)
```
    Assert that a collection contains no null elements.
    Note: Does not complain if the collection is empty!
    Assert.noNullElements(collection, "Collection must contain non-null elements");
    Parameters:
    collection - the collection to check
    message - the exception message to use if the assertion fails
    Throws:
    IllegalArgumentException - if the collection contains a null element
    Since:
    5.2
  - noNullElements
```
public static void noNullElements(@Nullable
                                  Collection<?> collection,
                                  Supplier<String> messageSupplier)
```
    Assert that a collection contains no null elements.
    Note: Does not complain if the collection is empty!
    Assert.noNullElements(collection, () -> "Collection " + collectionName + " must contain non-null 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 contains a null element
    Since:
    5.2
  - 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

Class Assert

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Assert

Method Detail

state

state

state

isTrue

isTrue

isTrue

isNull

isNull

isNull

notNull

notNull

notNull

hasLength

hasLength

hasLength

hasText

hasText

hasText

doesNotContain

doesNotContain

doesNotContain

notEmpty

notEmpty

notEmpty

noNullElements

noNullElements

noNullElements

notEmpty

notEmpty

notEmpty

noNullElements

noNullElements

notEmpty

notEmpty

notEmpty

isInstanceOf

isInstanceOf

isInstanceOf

isAssignable

isAssignable

isAssignable