我正在做一个程序，我在其中创建一个名为City
的对象的Arraylist City c1 = new City("Miami", "Florida", 33175, -80.4068, 25.7341);
City c2 = new City("Seattle", "Washington", 98109, -122.3476, 47.6339);
City c3 = new City("Levittown", "Pennsylvania", 19058, -75.1028, 40.3286);
City c4 = new City("Tampa", "Florida", 33625, -82.559, 28.0726);
City c5 = new City("Topeka", "Kansas", 66617, -95.6384, 39.1271);
ArrayList<City> cities = new ArrayList<City>();
cities.add(c1);
cities.add(c2);
cities.add(c3);
cities.add(c4);
cities.add(c5);
我需要使用下一个和上一个按钮逐个显示它。 目前我有一个for循环通过ArrayList创建标签和文本字段并从增量中获取类数据（i） 这是代码：
for (int i = 0; i < cities.size(); i++) {
GridPane pane = new GridPane();
pane.setHgap(5);
pane.setVgap(5);
pane.setPadding(new Insets(25,25,25,25));
Label label1 = new Label("City:");
TextField textField1 = new TextField (cities.get(i).getCity());
pane.add(label1, 0, 1);
pane.add(textField1, 1, 1);
Label label2 = new Label("State:");
TextField textField2 = new TextField (cities.get(i).getState());
pane.add(label2, 0, 2);
pane.add(textField2, 1, 2);
Label label3 = new Label("Zip Code:");
TextField textField3 = new TextField (String.valueOf(cities.get(i).getpostalCode()));
pane.add(label3, 0, 3);
pane.add(textField3, 1, 3);
Label label4 = new Label("Longitude:");
TextField textField4 = new TextField (String.valueOf(cities.get(i).getLongitude()));
pane.add(label4, 0, 4);
pane.add(textField4, 1, 4);
Label label5 = new Label("Longitude:");
TextField textField5 = new TextField (String.valueOf(cities.get(i).getLatitude()));
pane.add(label5, 0, 5);
pane.add(textField5, 1, 5);
Button prev = new Button("Previous");
pane.add(prev, 0, 20);
Button next = new Button("Next");
pane.add(next, 2, 20);
// buttons are work in progress
next.setOnAction((ActionEvent e) -> {
cities.get(i).getCity();
textField1.setText(cities.get(i).getCity());
});
BorderPane borderPane = new BorderPane();
borderPane.setCenter(pane);
Scene scene = new Scene(borderPane, 500, 500);
primaryStage.setTitle("Cities");
primaryStage.setScene(scene);
primaryStage.show();
}
我可以在没有ForLoop的情况下显示它，但我不知道如何从这里开始。另外，如何在循环中实现我的上一个/下一个按钮setOnActions？
谢谢！
答案 0 :(得分：2)
最好将显示城市的节点移动到新类。通过这种方式，您可以更轻松地分离问题。 （在实施导航时，您不需要考虑城市显示，反之亦然。）
public class CityView extends GridPane {
public CityView() {
setHgap(5);
setVgap(5);
setPadding(new Insets(25, 25, 25, 25));
Label label1 = new Label("City:");
TextField cityText = new TextField();
Label label2 = new Label("State:");
TextField stateText = new TextField();
Label label3 = new Label("Zip Code:");
TextField zipCodeText = new TextField();
Label label4 = new Label("Longitude:");
TextField longitudeText = new TextField();
Label label5 = new Label("Longitude:");
TextField latitudeText = new TextField();
addColumn(0, label1, label2, label3, label4, label5);
addColumn(1, cityText, stateText, zipCodeText, longitudeText, latitudeText);
this.city.addListener((o, oldValue, newValue) -> {
// fill TextFields with new city values
String name = null;
String state = null;
String zipCode = null;
String longitude = null;
String latitude = null;
if (city != null) {
name = newValue.getCity();
state = newValue.getState();
zipCode = String.valueOf(newValue.getpostalCode());
longitude = String.valueOf(newValue.getLongitude());
latitude = String.valueOf(newValue.getLatitude());
}
cityText.setText(name);
stateText.setText(state);
zipCodeText.setText(zipCode);
longitudeText.setText(longitude);
latitudeText.setText(latitude);
});
}
private final ObjectProperty<City> city = new SimpleObjectProperty<>(this, "city");
public ObjectProperty<City> cityProperty() {
return city;
}
public City getCity() {
return cityProperty().get();
}
public void setCity(City city) {
cityProperty().set(city);
}
}
@Override
public void start(Stage primaryStage) {
ObservableList<City> cities = FXCollections.observableArrayList(
new City("Miami", "Florida", 33175, -80.4068, 25.7341),
new City("Seattle", "Washington", 98109, -122.3476, 47.6339),
new City("Levittown", "Pennsylvania", 19058, -75.1028, 40.3286),
new City("Tampa", "Florida", 33625, -82.559, 28.0726),
new City("Topeka", "Kansas", 66617, -95.6384, 39.1271));
IntegerProperty index = new SimpleIntegerProperty();
IntegerBinding displayIndex = index.add(1);
IntegerBinding size = Bindings.size(cities);
size.addListener((o, oldValue, newValue) -> {
// keep index valid when cities are removed (not necessary for lists that are not modified)
int newSize = newValue.intValue();
int i = index.get();
if (i+1 >= newSize) {
index.set(Math.max(0, newSize - 1));
}
});
CityView cityView = new CityView();
cityView.cityProperty().bind(Bindings.valueAt(cities, index));
Button last = new Button("<");
last.setOnAction(evt -> {
index.set(index.get() - 1);
});
last.disableProperty().bind(index.lessThanOrEqualTo(0));
Button next = new Button(">");
next.setOnAction(evt -> {
index.set(index.get() + 1);
});
next.disableProperty().bind(displayIndex.greaterThanOrEqualTo(size));
Label indexLabel = new Label();
indexLabel.setMaxSize(Region.USE_PREF_SIZE, Double.MAX_VALUE);
indexLabel.setAlignment(Pos.CENTER_RIGHT);
indexLabel.setPrefWidth(20);
indexLabel.textProperty().bind(displayIndex.asString());
HBox navigation = new HBox(10, last, indexLabel, next);
navigation.setFillHeight(true);
VBox root = new VBox(cityView, navigation);
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.setResizable(false);
primaryStage.show();
}
答案 1 :(得分：1)
一个完整的最小样本将有助于回答，但正如你没有提供这个我只是描述你必须做的事情：
这段代码是我写的，所以它可能无法编译，但它只是为了给你一个方向
// Note that you could also do this by using the index, instead of city...
public void set(final City city) {
// assign values to the Nodes of the UI
// ...
// update the onAction Event for the NextButton
getNextButton().setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
//getNextIndexOf returns the index of the City+1 (if possible)
set(cities.get(getNextIndexOf(city));
}
});
// update the onAction Event for the PreviousButton
// do the equivalend as for the NextButton but decreasing the index
}