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java.lang.Objectorg.springframework.util.Assert
public abstract class Assert
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 config initialization code, there is usally 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 Jakarta's Commons Lang >= 2.0 for a more comprehensive suite of assertion utilities.
Constructor Summary | |
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Assert()
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Method Summary | |
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static void |
doesNotContain(String textToSearch,
String substring)
Assert that the given text does not contain the given substring. |
static void |
doesNotContain(String textToSearch,
String substring,
String message)
Assert that the given text does not contain the given substring. |
static void |
hasLength(String text)
Assert that a string is not empty; that is, it must not be null and not empty. |
static void |
hasLength(String text,
String message)
Assert that a string is not empty; that is, it must not be null and not empty. |
static void |
hasText(String text)
Assert that a string has valid text content; that is, it must not be null
and must contain at least one non-whitespace character. |
static void |
hasText(String text,
String message)
Assert that a string has 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 |
isInstanceOf(Class clazz,
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 |
isNull(Object object)
Assert that an object is null . |
static void |
isNull(Object object,
String message)
Assert that an object is null . |
static void |
isTrue(boolean expression)
Assert a boolean expression, throwing IllegalArgumentException
if the test result is false . |
static void |
isTrue(boolean expression,
String message)
Assert a boolean expression, throwing IllegalArgumentException
if the test result is false . |
static void |
notEmpty(Collection collection)
Assert that a collection has elements; that is, it must not be null and must have at least one element. |
static void |
notEmpty(Collection collection,
String message)
Assert that a collection has elements; that is, it must not be null and must have at least one element. |
static void |
notEmpty(Map map)
Assert that a Map has entries; that is, it must not be null
and must have at least one entry. |
static void |
notEmpty(Map map,
String message)
Assert that a Map has entries; that is, it must not be null
and must have at least one entry. |
static void |
notEmpty(Object[] array)
Assert that an array has elements; that is, it must not be null and must have at least one element. |
static void |
notEmpty(Object[] array,
String message)
Assert that an array has elements; that is, it must not be null and must have at least one element. |
static void |
notNull(Object object)
Assert that an object is not null . |
static void |
notNull(Object object,
String message)
Assert that an object is not null . |
static void |
state(boolean expression)
Assert a boolean expression, throwing IllegalStateException
if the test result is false . |
static void |
state(boolean expression,
String message)
Assert a boolean expression, throwing IllegalStateException
if the test result is false . |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public Assert()
Method Detail |
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public static void isTrue(boolean expression, String message)
IllegalArgumentException
if the test result is false
.
Assert.isTrue(i > 0, "The value must be greater than zero");
expression
- a boolean expressionmessage
- the exception message to use if the assertion fails
IllegalArgumentException
- if expression is false
public static void isTrue(boolean expression)
IllegalArgumentException
if the test result is false
.
Assert.isTrue(i > 0);
expression
- a boolean expression
IllegalArgumentException
- if expression is false
public static void isNull(Object object, String message)
null
.
Assert.isNull(value, "The value must be null");
object
- the object to checkmessage
- the exception message to use if the assertion fails
IllegalArgumentException
- if the object is not null
public static void isNull(Object object)
null
.
Assert.isNull(value);
object
- the object to check
IllegalArgumentException
- if the object is not null
public static void notNull(Object object, String message)
null
.
Assert.notNull(clazz, "The class must not be null");
object
- the object to checkmessage
- the exception message to use if the assertion fails
IllegalArgumentException
- if the object is null
public static void notNull(Object object)
null
.
Assert.notNull(clazz);
object
- the object to check
IllegalArgumentException
- if the object is null
public static void hasLength(String text, String message)
null
and not empty.
Assert.hasLength(name, "Name must not be empty");
text
- the string to checkmessage
- the exception message to use if the assertion failsStringUtils.hasLength(java.lang.String)
public static void hasLength(String text)
null
and not empty.
Assert.hasLength(name);
text
- the string to checkStringUtils.hasLength(java.lang.String)
public static void hasText(String text, String message)
null
and must contain at least one non-whitespace character.
Assert.hasText(name, "Name must not be empty");
text
- the string to checkmessage
- the exception message to use if the assertion failsStringUtils.hasText(java.lang.String)
public static void hasText(String text)
null
and must contain at least one non-whitespace character.
Assert.hasText(name, "Name must not be empty");
text
- the string to checkStringUtils.hasText(java.lang.String)
public static void doesNotContain(String textToSearch, String substring, String message)
Assert.doesNotContain(name, "rod", "Name must not contain 'rod'");
textToSearch
- the text to searchsubstring
- the substring to find within the textmessage
- the exception message to use if the assertion failspublic static void doesNotContain(String textToSearch, String substring)
Assert.doesNotContain(name, "rod");
textToSearch
- the text to searchsubstring
- the substring to find within the textpublic static void notEmpty(Object[] array, String message)
null
and must have at least one element.
Assert.notEmpty(array, "The array must have elements");
array
- the array to checkmessage
- the exception message to use if the assertion fails
IllegalArgumentException
- if the object array is null
or has no elementspublic static void notEmpty(Object[] array)
null
and must have at least one element.
Assert.notEmpty(array);
array
- the array to check
IllegalArgumentException
- if the object array is null
or has no elementspublic static void notEmpty(Collection collection, String message)
null
and must have at least one element.
Assert.notEmpty(collection, "Collection must have elements");
collection
- the collection to checkmessage
- the exception message to use if the assertion fails
IllegalArgumentException
- if the collection is null
or has no elementspublic static void notEmpty(Collection collection)
null
and must have at least one element.
Assert.notEmpty(collection, "Collection must have elements");
collection
- the collection to check
IllegalArgumentException
- if the collection is null
or has no elementspublic static void notEmpty(Map map, String message)
null
and must have at least one entry.
Assert.notEmpty(map, "Map must have entries");
map
- the map to checkmessage
- the exception message to use if the assertion fails
IllegalArgumentException
- if the map is null
or has no entriespublic static void notEmpty(Map map)
null
and must have at least one entry.
Assert.notEmpty(map);
map
- the map to check
IllegalArgumentException
- if the map is null
or has no entriespublic static void isInstanceOf(Class clazz, Object obj)
Assert.instanceOf(Foo.class, foo);
clazz
- the required classobj
- the object to check
IllegalArgumentException
- if the object is not an instance of clazzClass.isInstance(java.lang.Object)
public static void isInstanceOf(Class type, Object obj, String message)
Assert.instanceOf(Foo.class, foo);
type
- the type to check againstobj
- the object to checkmessage
- a message which will be prepended to the message produced by
the function itself, and which may be used to provide context. It should
normally end in a ": " or ". " so that the function generate message looks
ok when prepended to it.
IllegalArgumentException
- if the object is not an instance of clazzClass.isInstance(java.lang.Object)
public static void isAssignable(Class superType, Class subType)
superType.isAssignableFrom(subType)
is true
.
Assert.isAssignable(Number.class, myClass);
superType
- the super type to checksubType
- the sub type to check
IllegalArgumentException
- if the classes are not assignablepublic static void isAssignable(Class superType, Class subType, String message)
superType.isAssignableFrom(subType)
is true
.
Assert.isAssignable(Number.class, myClass);
superType
- the super type to check againstsubType
- the sub type to checkmessage
- a message which will be prepended to the message produced by
the function itself, and which may be used to provide context. It should
normally end in a ": " or ". " so that the function generate message looks
ok when prepended to it.
IllegalArgumentException
- if the classes are not assignablepublic static void state(boolean expression, String message)
IllegalStateException
if the test result is false
. Call isTrue if you wish to
throw IllegalArgumentException on an assertion failure.
Assert.state(id == null, "The id property must not already be initialized");
expression
- a boolean expressionmessage
- the exception message to use if the assertion fails
IllegalStateException
- if expression is false
public static void state(boolean expression)
IllegalStateException
if the test result is false
.
Call isTrue(boolean)
if you wish to
throw IllegalArgumentException
on an assertion failure.
Assert.state(id == null);
expression
- a boolean expression
IllegalStateException
- if the supplied expression is false
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