Class GroupValidator

java.lang.Object
org.netbeans.validation.api.ui.GroupValidator
public abstract class GroupValidator extends Object
Encapsulates validation of the combination of several UI components within a ValidationGroup.

UI-components whose validity depends not only on their own state but on the state of each other as well, can be said to have validity interdependencies. In such cases not only the state of each component needs to be validated as a singular, but the combination of components needs to be validated as well.

The following items outline what needs to be done to achieve this.

  • The UI components with interdependencies need to be added to the same ValidationGroup
  • This ValidationGroup needs to be prepared at creation time with an instance of GroupValidator.
  • In this GroupValidator, the method performGroupValidation(org.netbeans.validation.api.Problems) needs to be overridden to perform the custom interdependency validation.

When a UI component is changed (either programmatically or by having been interacted with by the user) the following will happen:

  • As usual, the UI component will be revalidated using its connected validators.
  • Now, only if there is no fatal Problem in any of the UI components within the ValidationGroup, the validation in the GroupValidator will be invoked as well.
  • If it turns out that the latter yields a Problem more severe (i.e strictly worse) than any other Problem in the ValidationGroup, then this Problem will become the lead problem in the group.
  • The lead problem of the group (whichever it may be) is shown as usual in the ValidationUI(s) of the ValidationGroup.
  • If the lead Problem happens to be the one caused by the GroupValidator, then the default behavior is that this Problem will cause all UI components within the ValidationGroup to be decorated. This behavior can however be disabled by passing false to the constructor GroupValidator(boolean)

The following code example illustrates how this class can be used. 

        // Given three text fields, aField, bField and cField, this class validates
        // that the sum of the numbers in them equals a number given in a combo box.
        class SumValidation extends GroupValidator {
            SumValidation() {
                // The boolean specifies whether a Problem generated by the
                // GroupValidator should cause the UI-components in the
                // ValidationGroup to be decorated or not
                super(true);
            }
            @Override
            protected void performGroupValidation(Problems problems) {
                try {
                    int desiredSum = Integer.parseInt(sumComboBox.getModel().getSelectedItem().toString());
                    int val1 = Integer.parseInt(aField.getText());
                    int val2 = Integer.parseInt(bField.getText());
                    int val3 = Integer.parseInt(cField.getText());
                    int sum = val1 + val2 + val3;
                    if (sum != desiredSum) {
                        problems.add( new Problem (val1 + "+" + val2 + "+" + val3 +
                                " equals " + sum + ", not " + desiredSum, Severity.FATAL));
                    } else if (val1 == desiredSum || val2 == desiredSum || val3 == desiredSum) {
                        problems.add( new Problem ("Hey...that's cheating!",
                                Severity.WARNING) );
                    }
                } catch (NumberFormatException e) {
                    //do nothing, the other validators would have taken care of the bad entry
                }
            }
        }

        // The GroupValidator can be used as follows:

        // Create ValidationGroup that will contain UI component with validity
        // interdependencies. Pass a GroupValidator -- SumValidation -- to the
        // ValidationGroup creator.
        SwingValidationGroup bunch = SwingValidationGroup.create(new SumValidation());

        // Create a Validator that can be reused for individual validation of
        // the three text fields
        Validator<String> fieldValidator =
                StringValidators.trimString(StringValidators.REQUIRE_NON_EMPTY_STRING,
                StringValidators.NO_WHITESPACE,
                StringValidators.REQUIRE_VALID_NUMBER,
                StringValidators.REQUIRE_VALID_INTEGER,
                StringValidators.REQUIRE_NON_NEGATIVE_NUMBER);

        bunch.add(aField, fieldValidator);
        bunch.add(bField, fieldValidator);
        bunch.add(cField, fieldValidator);

        // Add the combo box as well so that the additional group
        // validation is triggered whenever the combo box is interacted with. Note
        // that there are no validators added for the combo box alone. Also, ValidationUI.NoOp.get()
        // is passed, so that the combo box will not be decorated when there's a problem.
        bunch.add(SwingValidationListenerFactory.createJComboBoxValidationListener(sumComboBox, ValidationUI.NoOp.get()));
Author:
Hugo Heden

  • Constructor Details

    • GroupValidator

      protected GroupValidator()
      Default constructor, calls this(true)

    • GroupValidator

      protected GroupValidator(boolean shallShowProblemInChildrenUIs)
      Parameters:
      shallShowProblemInChildrenUIs - specifies whether a Problem generated by the GroupValidator (if it happens to be the lead Problem) should cause the UI-components in the ValidationGroup to be decorated (showing the Problem) or not

  • Method Details

    • performGroupValidation

      protected abstract void performGroupValidation(Problems problems)
      Validate the state of the combination of the UI components within the ValidationGroup. If invalid this method shall add one or more Problems to the passed list.
      Parameters:
      problems - A list of problems.