Package org.zkoss.zul

## Interface Constraint

- All Known Implementing Classes:
    `AbstractSimpleDateTimeConstraint`, `SimpleConstraint`, `SimpleDateConstraint`, `SimpleDecimalboxConstraint`, `SimpleDoubleboxConstraint`, `SimpleDoubleSpinnerConstraint`, `SimpleIntboxConstraint`, `SimpleLocalDateConstraint`, `SimpleLocalTimeConstraint`, `SimpleLongboxConstraint`, `SimpleNumberInputConstraint`, `SimpleSpinnerConstraint`

      public interface Constraint

  A constraint. Instead of implementing this interface, you may use `SimpleConstraint` if applicable.

  To have better responsiveness, you can handle all (or some) validation at the client by implementing an additional interface, `ClientConstraint`.

  If you prefer to have a custom way to display the error message (other than the default error box). You can also implement `CustomConstraint`. Then, `CustomConstraint.showCustomError(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.WrongValueException)` is called instead of showing the default error box.

  Since 5.0.0, `ClientConstraint` takes higher priority if both implemented.

  Author:
    tomyeh
  See Also:
    `CustomConstraint`, `ClientConstraint`

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `validate​(Component comp, java.lang.Object value)` | Verifies whether the value is acceptable.

- - ### Method Detail

    - #### validate

          void validate​(Component comp,
                        java.lang.Object value)
                 throws WrongValueException

      Verifies whether the value is acceptable.
      Parameters:
        `comp` - the component being validated
      Throws:
        `WrongValueException`