Vaadin回傳組件值

我在 Vaadin 中作業，我想檢索組件中選擇的所有值，但它們始終為空。

這是定義組件并將其存盤在 ArrayLIst 中以發送到專案的另一個類和方法的類。

public class MainView extends Div {

    ProjectConfiguration configuration = new ProjectConfiguration();

    private final List<String> visualizationList = new ArrayList<>(Arrays.asList("FAST", "REAL TIME"));
    private final List<String> resolutionList = new ArrayList<>(Arrays.asList("320 x 200", "640 x 400"));
    private final List<String> audioRate = new ArrayList<>(Arrays.asList("44100", "48000"));

    public void ShowForm() {

        ComboBoxs comboResolution = new ComboBoxs(resolutionList,"Video resolution","Select a resolution for the exported video");
        ComboBoxs comboVideoVisualization = new ComboBoxs(visualizationList,"Export visualization", "Select the visualization of the video export");
        ComboBoxs comboAudioRate = new ComboBoxs(audioRate,"Audio rate", "Select the audio rate for the video export");
        CheckStats checkStats = new CheckStats();
        ArrayList<Div> fieldValues = new ArrayList<Div>();
        fieldValues.add(comboResolution);
        fieldValues.add(comboVideoVisualization);
        fieldValues.add(comboAudioRate);
        fieldValues.add(checkStats);
        SubmitButton submitButton = new SubmitButton(configuration, fieldValues);
    }
}

這個提交按鈕正在將此配置寫入一個全域 POJO 類。

public class SubmitButton extends Div {

public SubmitButton(ProjectConfiguration configuration, ArrayList<Div> fields) {
    Button submitButton = new Button("Create video");

    submitButton.addClickListener(clickEvent -> {
        submitConfiguration(configuration, fields);
    });
    add(submitButton);
}
private void submitConfiguration(ProjectConfiguration configuration, ArrayList<Div> fields) {
    new FieldGetter(configuration, fields);
}
}

同樣的實體，如果我將它發送到這個類之外的一個新方法，我總是得到一個空值。

public class FieldGetter {

    public FieldGetter(ProjectConfiguration configuration, ArrayList<Div> fields, String exportFileName) {
        log.info("Text 1 "   fields.get(0).getText());
        log.info("Text 2 "   fields.get(1).getText());
        log.info("Text 3 "   fields.get(2).getText());
        log.info("Text 4 "   fields.get(3).getText());
}}

所有這些組件都有資訊。選中所有 ComboBox，并單擊 Stats。我做錯了什么？我需要使用哪種方法來獲得選擇。非常感謝。

我正在按要求添加實作的 ComboBoxs 類。

@Route("combo")
public class ComboBoxs extends Div {

    public ComboBoxs(List<String> arrayList, String label, String helperText) {
        ComboBox<String> comboBox = new ComboBox<>(label);
        comboBox.setAllowCustomValue(true);
        comboBox.addCustomValueSetListener(e -> {
            String customValue = e.getDetail();
            arrayList.add(customValue);
            comboBox.setItems(arrayList);
            comboBox.setValue(customValue);
        });
        add(comboBox);
        comboBox.setItems(arrayList);
        comboBox.setHelperText(helperText);
    }
}

uj5u.com熱心網友回復：

Your FieldGetter is looking at the wrong place. Those Divs have no texts set (which might be what you assumed would happen by comboBox.setValue(customValue)).

Generally, your code is a bit convoluted. You don't need all those Divs and abstractions.

Try

public class HelloWorldView extends HorizontalLayout {

private final List<String> visualizationList = new ArrayList<>(Arrays.asList("FAST", "REAL TIME"));

public HelloWorldView() {
    ComboBox<String> comboBox = new ComboBox<>("Visualisation");
    comboBox.setAllowCustomValue(true);
    comboBox.addCustomValueSetListener(e -> {
        String customValue = e.getDetail();
        visualizationList.add(customValue);
        comboBox.setItems(visualizationList);
        comboBox.setValue(customValue);
    });
    add(comboBox);
    comboBox.setItems(visualizationList);

    Button printValues = new Button("Print");
    printValues.addClickListener(e -> {
        System.out.println(Arrays.toString(visualizationList.toArray(new String[0])));
        System.out.println("Value is now:"  comboBox.getValue() );
    });
    comboBox.addValueChangeListener(e-> System.out.println("Value changed from "    e.getOldValue()   " to "   e.getValue()));
    add(printValues);        }       }

Start, the program (I used the starter from start.vaadin.com), select "FAST", then delete "FAST", enter "Slow" and hit <return/enter>. Then click the print button.

The output will look like this:

Value changed from null to FAST
Value changed from FAST to null
Value changed from null to Slow
[FAST, REAL TIME, Slow]
Value is now:Slow

Hope this helps!

標籤：爪哇 春天 形式 成分 vaadin

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