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. * *
When a UI component is changed (either programmatically or by * having been interacted with by the user) the following will happen: * *
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
*/
public abstract class GroupValidator {
private final boolean shallShowProblemInChildrenUIs;
private boolean isCurrentlyLeadingProblem = false;
/**
* Default constructor, calls {@code this(true)}
*/
protected GroupValidator() {
this( true );
}
/**
* @param shallShowProblemInChildrenUIs specifies whether a
* Problem generated by the {@code GroupValidator} (if it happens
* to be the lead {@code Problem}) should cause the UI-components
* in the {@code ValidationGroup} to be decorated (showing the
* {@code Problem}) or not
*/
protected GroupValidator(boolean shallShowProblemInChildrenUIs ) {
this.shallShowProblemInChildrenUIs = shallShowProblemInChildrenUIs;
}
final boolean isCurrentlyLeadingProblem() {
return isCurrentlyLeadingProblem;
}
final void setIsCurrentlyLeadingProblem(boolean isCurrentlyLeadingProblem) {
this.isCurrentlyLeadingProblem = isCurrentlyLeadingProblem;
}
final boolean shallShowProblemInChildrenUIs() {
return shallShowProblemInChildrenUIs;
}
/**
* Validate the state of the combination of the UI components
* within the ValidationGroup. If invalid
* this method shall add one or more {@code Problem}s to
* the passed list.
*
* @param problems A list of problems.
*/
protected abstract void performGroupValidation(Problems problems);
}