嘿伙计们，我有这个小问题。我是Java的新手，我只想弄清楚“如何在我的代码中的列表视图末尾添加另一个项目”。这应该在程序运行时动态发生。我只想点击列表视图底部的相应空间，只需添加一个项目。有人可以帮我解决这个问题。谢谢！
注意：运行应用程序，一切都会出现在那里。我只是想为这些按钮添加功能。当我点击“添加”按钮时，我应该可以添加更多项目。
package layoutsizingaligning;
import java.util.Scanner;
import javafx.application.Application;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Orientation;
import javafx.scene.control.Control;
import javafx.scene.Scene;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ListView;
import javafx.scene.control.PasswordField;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.control.TextField;
import javafx.scene.layout.*;
import javafx.stage.Stage;
/**
* Sample application that shows how the sized of controls can be managed.
* Sample is for demonstration purposes only, most controls are inactive.
*/
public class LayoutSizingAligning extends Application {
// Define buttons here for access by multiple methods
private Button btnApply = new Button("Apply");
private Button btnContinue = new Button("Continue");
private Button btnExit = new Button("Exit");
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
Application.launch(LayoutSizingAligning.class, args);
}
//@Override
public void start(Stage primaryStage) {
// Make Exit button bigger by using larger font for label
//btnExit.setStyle("-fx-font-size: 12pt;");
// Use tab pane with one tab for sizing UI and one tab for alignment UI
TabPane tabs = new TabPane();
Tab tabSize = new Tab();
tabSize.setText("Sizing");
tabSize.setContent(sizingSample());
Tab tabAlign = new Tab();
tabAlign.setText("Alignment");
tabAlign.setContent(alignmentSample());
tabs.getTabs().addAll(tabSize, tabAlign);
Scene scene = new Scene(tabs, 300, 400); // Manage scene size
primaryStage.setTitle("Sizing and Aligning");
primaryStage.setScene(scene);
primaryStage.show();
}
/*
* Creates the UI for the sizing sample, which demonstrates ways to manage
* the size of controls when you don't want the default sizes.
*/
private Pane sizingSample() {
BorderPane border = new BorderPane();
border.setPadding(new Insets(20, 0, 20, 20));
ListView<String> lvList = new ListView<String>();
ObservableList<String> items = FXCollections.observableArrayList (
"Hot dog", "Hamburger", "French fries",
"Carrot sticks", "Chicken salad");
// Scanner scan = new Scanner(System.in);
// String s = scan.next();
// items.add(s);
lvList.setItems(items);
lvList.setMaxHeight(Control.USE_PREF_SIZE);
lvList.setPrefWidth(150.0);
border.setLeft(lvList);
border.setRight(createButtonColumn());
border.setBottom(createButtonRow()); // Uses a tile pane for sizing
// border.setBottom(createButtonBox()); // Uses an HBox, no sizing
return border;
}
/*
* Creates the UI for the alignment sample, which demonstrates ways to manage
* the alignment of controls when you don't want the default alignment.
*/
private Pane alignmentSample() {
GridPane grid = new GridPane();
grid.setAlignment(Pos.CENTER); // Override default
grid.setHgap(10);
grid.setVgap(12);
// Use column constraints to set properties for columns in the grid
ColumnConstraints column1 = new ColumnConstraints();
column1.setHalignment(HPos.RIGHT); // Override default
grid.getColumnConstraints().add(column1);
ColumnConstraints column2 = new ColumnConstraints();
column2.setHalignment(HPos.LEFT); // Override default
grid.getColumnConstraints().add(column2);
HBox hbButtons = new HBox();
hbButtons.setSpacing(10.0);
hbButtons.setAlignment(Pos.CENTER); // Aligns HBox and controls in HBox
Button btnSubmit = new Button("Submit");
Button btnClear = new Button("Clear");
Button btnExit2 = new Button("Exit");
//btnSubmit.setStyle("-fx-font-size: 15pt;");
Label lblName = new Label("User name:");
TextField tfName = new TextField();
Label lblPwd = new Label("Password:");
PasswordField pfPwd = new PasswordField();
hbButtons.getChildren().addAll(btnSubmit, btnClear, btnExit2);
grid.add(lblName, 0, 0);
grid.add(tfName, 1, 0);
grid.add(lblPwd, 0, 1);
grid.add(pfPwd, 1, 1);
grid.add(hbButtons, 0, 2, 2, 1);
/* Uncomment the following statements to bottom-align the buttons */
// hbButtons.setAlignment(Pos.BOTTOM_CENTER);
// GridPane innergrid = new GridPane();
// innergrid.setAlignment(Pos.CENTER);
// innergrid.add(hbButtons, 0, 0);
// grid.add(innergrid, 0, 2, 2, 1);
return grid;
}
/*
* Creates a column of buttons and makes them all the same width as the
* largest button.
*/
private VBox createButtonColumn() {
Button btnAdd = new Button("Add");
Button btnDelete = new Button("Delete");
Button btnMoveUp = new Button("Move Up");
Button btnMoveDown = new Button("Move Down");
// Comment out the following statements to see the default button sizes
btnAdd.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
btnDelete.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
btnMoveUp.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
btnMoveDown.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
btnMoveDown.setMinWidth(Control.USE_PREF_SIZE);
btnAdd.setOnAction(new EventHandler<ActionEvent>() {
//@Override
public void handle(ActionEvent event) {
Scanner scan = new Scanner(System.in);
String s = scan.next();
}
});
VBox vbButtons = new VBox();
vbButtons.setSpacing(10);
vbButtons.setPadding(new Insets(0, 20, 10, 20));
vbButtons.getChildren().addAll(
btnAdd, btnDelete, btnMoveUp, btnMoveDown);
return vbButtons;
}
/*
* Creates a row of buttons and makes them all the same size.
*/
private TilePane createButtonRow() {
// Let buttons grow, otherwise they will be different sizes based
// on the length of the label
btnApply.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
btnContinue.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
btnExit.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
btnExit.setOnAction(new EventHandler<ActionEvent>() {
//@Override
public void handle(ActionEvent event) {
System.exit(0);
}
});
TilePane tileButtons = new TilePane(Orientation.HORIZONTAL);
tileButtons.setPadding(new Insets(20, 10, 20, 0));
tileButtons.setHgap(10.0);
tileButtons.setVgap(8.0); // In case window is reduced and buttons
// require another row
tileButtons.getChildren().addAll(btnApply, btnContinue, btnExit);
return tileButtons;
}
/*
* Creates a row of buttons with the default sizes.
*/
private HBox createButtonBox() {
HBox hbButtons = new HBox();
hbButtons.setSpacing(10);
hbButtons.setPadding(new Insets(20, 10, 20, 0));
hbButtons.getChildren().addAll(btnApply, btnContinue, btnExit);
return hbButtons;
}
}
答案 0 :(得分：2)
首先，您需要将ListView放在可访问的位置，以便稍后再次查找引用。因此，不要将其声明为局部变量，而应将其声明为字段。
然后，要添加项目，您只需执行以下操作：
listview.getItems().add("some new element");