Package net.sf.eBus.util

Class Validator

java.lang.Object

net.sf.eBus.util.Validator

public class Validator
extends Object

This class is used to collect invalid builder settings, combining the invalid field names with text explaining why the field is invalid. Helper methods are provided to perform the most common checks (not null, not null or empty string, and equals value). If the check fails, then the given field name and appropriate reason are added to the errors list.

If validation requires more sophisticated validation, requireTrue(Predicate, Object, String, String) and requireTrue(BiPredicate, Object, Object, String, String, String) are provided. The user provides a predicate which tests either a single field or two fields in combination. If predicate.test returns false, then the field or fields are marked as invalid. The BiPredicate method may be used to test two fields which are mutually dependent. This means that setting one field to a given value limits the value which may be assigned to the other. If this bi-predicate fails, then both fields are in error.

If the provided requires methods are not sufficient (such as testing the mutual validity of three or more fields), then the user must use custom validation code and, if the validation fails, use addError(MultiKey2) to enter the error into the validation error list.

Author:

Charles W. Rapp

Field Summary

Fields

Modifier and Type	Field	Description
static int	MESSAGE_INDEX	The message explaining why the field is invalid is stored in index 1.
static int	NAME_INDEX	The field name is stored in index 0.
static String	NEWLINE	OS-specific end-of-line string for quick reference.
static String	NOT_SET	Standard reason for a required message field not being set.

Constructor Summary

Constructors

Constructor	Description
Validator()	Creates a new validator instance containing no problems.

Method Summary

Modifier and Type	Method	Description
Validator	addError(MultiKey2<String,String> error)	Adds the given error to the validator error list.
List<MultiKey2<String,String>>	errors()	Returns an unmodifiable copy of the field errors list.
boolean	isEmpty()	Returns true if there are no validation errors and false otherwise.
Validator	requireEquals(Object value, Object expected, String fieldName)	Check if the field value equals the expected value and, if not, adds the appropriate error against the field name.
Validator	requireNotNull(Object value, String fieldName)	Checks if the given value is null and, if so, adds the appropriate error against the field name.
Validator	requireNotNullOrEmpty(String value, String fieldName)	Checks if the given String value is either null or empty and, if so, adds the appropriate error against the field name.
Validator	requireTrue(boolean flag, String fieldName, String message)	If flag is false, then an error is raised for the given field name and message.
<V1,V2> Validator	requireTrue(BiPredicate<V1,V2> predicate, V1 value1, V2 value2, String fieldName1, String fieldName2, String message)	If predicate.test(value) returns false, then the given field name and message are added to the field errors list.
<V> Validator	requireTrue(Predicate<V> predicate, V value, String fieldName, String message)	If predicate.test(value) returns false, then the given field name and message are added to the field errors list.
int	size()	Returns error count.
void	throwException(Class<?> tc)	Throws a ValidationException if this validator contains any problems.
void	throwException(Class<?> tc, Throwable cause)	Throws a ValidationException if this validator contains any problems.
String	toString()	Returns the error list as text which each error output as "<field name>: <message>" on a separate line.

Methods inherited from class java.lang.Object

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

Field Detail

NEWLINE

public static final String NEWLINE

OS-specific end-of-line string for quick reference.

NOT_SET

public static final String NOT_SET

Standard reason for a required message field not being set.

See Also:

Constant Field Values

NAME_INDEX

public static final int NAME_INDEX

The field name is stored in index 0.

See Also:

Constant Field Values

MESSAGE_INDEX

public static final int MESSAGE_INDEX

The message explaining why the field is invalid is stored in index 1.

See Also:

Constant Field Values

Constructor Detail

Validator

public Validator()

Creates a new validator instance containing no problems.

Method Detail

toString

public String toString()

Returns the error list as text which each error output as "<field name>: <message>" on a separate line. If there are no errors, then returns an empty string.

Overrides:

toString in class Object

Returns:

textual representation of error list.

isEmpty

public boolean isEmpty()

Returns true if there are no validation errors and false otherwise.

Returns:

true if there are no validation errors.

size

public int size()

Returns error count.

Returns:

error count.

errors

public List<MultiKey2<String,String>> errors()

Returns an unmodifiable copy of the field errors list.

Returns:

field errors list.

addError

public Validator addError(MultiKey2<String,String> error)

Adds the given error to the validator error list. If error is null, then it is ignored and nothing is added to the errors list. This is done to allow this method to be used in a Validator method chain

Parameters:

error - invalid field error. Ignored if null.

Returns:

this Validator instance.

requireNotNull

public Validator requireNotNull(Object value,
                                String fieldName)

Checks if the given value is null and, if so, adds the appropriate error against the field name.

Parameters:

value - field value.

fieldName - name of field containing value.

Returns:

this Validator instance.

See Also:

requireNotNullOrEmpty(String, String)

requireNotNullOrEmpty

public Validator requireNotNullOrEmpty(String value,
                                       String fieldName)

Checks if the given String value is either null or empty and, if so, adds the appropriate error against the field name.

Parameters:

value - string field value.

fieldName - name of field containing value.

Returns:

this Validator instance.

See Also:

requireNotNull(Object, String)

requireEquals

public Validator requireEquals(Object value,
                               Object expected,
                               String fieldName)

Check if the field value equals the expected value and, if not, adds the appropriate error against the field name.

Parameters:

value - field value.

expected - expected value.

fieldName - name of field containing value.

Returns:

this Validator instance.

requireTrue

public <V> Validator requireTrue(Predicate<V> predicate,
                                 V value,
                                 String fieldName,
                                 String message)

If predicate.test(value) returns false, then the given field name and message are added to the field errors list. This method allows for more sophisticated test beyond check for a null value or equality.

Please note that predicate.test(value) should return true if value is acceptable. Do not write the predicate test method to check if value is not valid.

Type Parameters:

V - value type.

Parameters:

predicate - test method checks if value is acceptable.

value - field value.

fieldName - name of field containing value.

message - error message if predicate.test(value) returns false.

Returns:

this Validator instance.

See Also:

requireTrue(BiPredicate, Object, Object, String, String, String), requireTrue(boolean, String, String)

requireTrue

public <V1,V2> Validator requireTrue(BiPredicate<V1,V2> predicate,
                                           V1 value1,
                                           V2 value2,
                                           String fieldName1,
                                           String fieldName2,
                                           String message)

If predicate.test(value) returns false, then the given field name and message are added to the field errors list. This method allows for tests which require checking two fields against each other when their individual validity is dependent on the fields being mutually consistent. That is, setting the first field to a given value limits what value may be set to the second field.

Please note that predicate.test(value) should return true if value is acceptable. Do not write the predicate test method to check if value is not valid.

Type Parameters:

V1 - value1 type.

V2 - value2 type.

Parameters:

predicate - test method checks if value1 and value2 are mutually acceptable.

value1 - first field's value.

value2 - second field's value.

fieldName1 - first field's name.

fieldName2 - second field's name.

message - message applied to both fields if predicate.test(value1, value2) returns false.

Returns:

this Validator instance.

See Also:

requireTrue(Predicate, Object, String, String), requireTrue(boolean, String, String)

requireTrue

public Validator requireTrue(boolean flag,
                             String fieldName,
                             String message)

If flag is false, then an error is raised for the given field name and message.

Parameters:

flag - set to true if the field is valid and false is invalid.

fieldName - validating this field name.

message - message explaining invalidation.

Returns:

this Validator instance.

See Also:

requireTrue(Predicate, Object, String, String), requireTrue(BiPredicate, Object, Object, String, String, String)

throwException

public void throwException(Class<?> tc)

Throws a ValidationException if this validator contains any problems. Otherwise does nothing.

Parameters:

tc - validation exception applies to building this class.

Throws:

ValidationException - if this validator has any listed problems.

throwException

public void throwException(Class<?> tc,
                           Throwable cause)

Throws a ValidationException if this validator contains any problems. Otherwise does nothing.

Parameters:

tc - validation exception applies to building this class.

cause - underlying exception causing this validation exception.

Throws:

ValidationException - if this validator has any listed problems.