# Interface Constraint

All Known Implementing Classes:
  `ExistInConstraint, GroupConstraint, LengthConstraint, NotConstraint, NumericConstraint, RegexConstraint`

public interface Constraint
To perform validation we add a constraint to a validator, a constraint defines whether a value if valid for a given object

- ## Method Summary

  Modifier and Type
  Method
  Description
  `String`
  `getDefaultFailMessage()`
  Includes the error message for the constraint
  `boolean`
  `isValid(java.lang.Object value)`
  Indicates if the given value is valid or not

- ## Method Details

  - ### isValid

    boolean isValid(java.lang.Object value)

    Indicates if the given value is valid or not

    ###### Parameters

    - `value`: the value for the object

    ###### Returns

    true if the value is valid and false otherwise

  - ### getDefaultFailMessage

    String getDefaultFailMessage()

    Includes the error message for the constraint

    ###### Returns

    the text of the error message for a constraint