Package org.apache.shiro.lang.util

Class Assert

java.lang.Object
org.apache.shiro.lang.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. Usage also reduces a program's cyclomatic complexity.

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 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 Jakarta's Commons Lang >= 2.0 for a more comprehensive suite of assertion utilities.

Gratefully borrowed from the Spring Framework, also Apache 2.0 licensed

Since:
1.3

  • Constructor Summary

    Constructors
    Constructor
    Description
    Assert()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    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 the given String is not empty; that is, it must not be null and not the empty 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
    hasText(String text)
    Assert that the given 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 the given 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
    noNullElements(Object[] array)
    Assert that an array has no null elements.
    static void
    noNullElements(Object[] array, String message)
    Assert that an array has no null elements.
    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
    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
    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

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

  • Constructor Details

    • Assert

      public Assert()

  • Method Details

    • isTrue

      public static void isTrue(boolean expression, String message)
      Assert a boolean expression, throwing IllegalArgumentException if the test result is 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)
      Assert a boolean expression, throwing IllegalArgumentException if the test result is false. 
      Assert.isTrue(i > 0);
      Parameters:
      expression - a boolean expression
      Throws:
      IllegalArgumentException - if expression is false

    • isNull

      public static void isNull(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(Object object)
      Assert that an object is null . 
      Assert.isNull(value);
      Parameters:
      object - the object to check
      Throws:
      IllegalArgumentException - if the object is not null

    • notNull

      public static void notNull(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(Object object)
      Assert that an object is not null . 
      Assert.notNull(clazz);
      Parameters:
      object - the object to check
      Throws:
      IllegalArgumentException - if the object is null

    • hasLength

      public 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. 
      Assert.hasLength(name, "Name must not be empty");
      Parameters:
      text - the String to check
      message - the exception message to use if the assertion fails
      See Also:

    • hasLength

      public static void hasLength(String text)
      Assert that the given String is not empty; that is, it must not be null and not the empty String. 
      Assert.hasLength(name);
      Parameters:
      text - the String to check
      See Also:

    • hasText

      public static void hasText(String text, String message)
      Assert that the given String has 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
      See Also:

    • hasText

      public static void hasText(String text)
      Assert that the given String has 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
      See Also:

    • doesNotContain

      public static void doesNotContain(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

    • doesNotContain

      public static void doesNotContain(String textToSearch, String substring)
      Assert that the given text does not contain the given substring. 
      Assert.doesNotContain(name, "rod");
      Parameters:
      textToSearch - the text to search
      substring - the substring to find within the text

    • notEmpty

      public 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. 
      Assert.notEmpty(array, "The array must have 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 has no elements

    • notEmpty

      public 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. 
      Assert.notEmpty(array);
      Parameters:
      array - the array to check
      Throws:
      IllegalArgumentException - if the object array is null or has no elements

    • noNullElements

      public static void noNullElements(Object[] array, String message)
      Assert that an array has no null elements. Note: Does not complain if the array is empty! 
      Assert.noNullElements(array, "The array must have 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(Object[] array)
      Assert that an array has no null elements. Note: Does not complain if the array is empty! 
      Assert.noNullElements(array);
      Parameters:
      array - the array to check
      Throws:
      IllegalArgumentException - if the object array contains a null element

    • notEmpty

      public 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. 
      Assert.notEmpty(collection, "Collection must have 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 has no elements

    • notEmpty

      public 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. 
      Assert.notEmpty(collection, "Collection must have elements");
      Parameters:
      collection - the collection to check
      Throws:
      IllegalArgumentException - if the collection is null or has no elements

    • notEmpty

      public 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. 
      Assert.notEmpty(map, "Map must have 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 has no entries

    • notEmpty

      public 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. 
      Assert.notEmpty(map);
      Parameters:
      map - the map to check
      Throws:
      IllegalArgumentException - if the map is null or has no entries

    • isInstanceOf

      public static void isInstanceOf(Class clazz, Object obj)
      Assert that the provided object is an instance of the provided class. 
      Assert.instanceOf(Foo.class, foo);
      Parameters:
      clazz - the required class
      obj - the object to check
      Throws:
      IllegalArgumentException - if the object is not an instance of clazz
      See Also:

    • isInstanceOf

      public static void isInstanceOf(Class type, Object obj, String message)
      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
      message - 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.
      Throws:
      IllegalArgumentException - if the object is not an instance of clazz
      See Also:

    • 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

    • isAssignable

      public static void isAssignable(Class superType, Class subType, String message)
      Assert that superType.isAssignableFrom(subType) is true. 
      Assert.isAssignable(Number.class, myClass);
      Parameters:
      superType - the super type to check against
      subType - the sub type to check
      message - 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.
      Throws:
      IllegalArgumentException - if the classes are not assignable

    • state

      public static void state(boolean expression, String message)
      Assert a boolean expression, throwing 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");
      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)
      Assert a boolean expression, throwing IllegalStateException if the test result is false.

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

      Assert.state(id == null);
      Parameters:
      expression - a boolean expression
      Throws:
      IllegalStateException - if the supplied expression is false