在 JavaFX 中，如何以编程方式将 Scrollpane 滚动到底部？
In JavaFX how can I programmatically scroll a Scrollpane to the bottom?
我一直在为我和一些朋友开发一个小型聊天客户端，同时自学 Java 和 JFX 8。不幸的是，出于某种原因，我无法以编程方式滚动到聊天消息所在的 ScrollPane 底部。
我有一个名为 scrollToBottom() 的方法，它执行以下代码：
public void scrollToBottom() {
Platform.runLater(() -> this.getChatView().vvalueProperty().setValue(1.0));
}
我有一个按钮可以使用此方法滚动到底部，但任何其他编程方法（甚至从其他方法触发按钮）都无法正确更新滚动窗格的滚动条。但是，当我在假定滚动后在滚动窗格上调用 getVvalue() 时，它 returns 是我试图让它滚动的正确值。滚动窗格只是没有滚动到假定的值。
下面是应用程序中唯一真正相关的 class - ChatBox 类型只是 VBox 的扩展，它仅使用扩展类型的文本。
public class MainScreenController {
//Lists
//Buttons
private Button logoutButton;
private Button btn1 = new Button("Test Button");
private Button scrollButton = new Button("Scroll Button");
//Numbers
//Booleans
private boolean isHosting;
//Strings
private String username = "";
//Scene
private Stage window;
private GridPane layout = new GridPane();
//Other Objects
private TextArea chatField = new TextArea();
private Label usernameLabel;
private TextArea usersArea = new TextArea("Connected users: ");
private VBox firstColumn = new VBox(10);
private VBox secondColumn = new VBox(10);
private ImageView mediaColumn = new ImageView();
private Server server = new Server();
private Client client = new Client();
private TextField dlField = new TextField();
private AudioHandler audioHandler = new AudioHandler();
private ChatBox chatBox = new ChatBox();
private ScrollPane chatView = new ScrollPane(this.chatBox);
private HBox buttonBox = new HBox(10);
private void initChatView() {
this.getChatView().setMinSize(500, 500);
this.getChatView().setPrefSize(500, 500);
this.getChatView().setMaxSize(500, 500);
this.getChatView().setStyle("-fx-focus-color: transparent; -fx-background-color: gainsboro");
this.chatView.hbarPolicyProperty().set(ScrollBarPolicy.NEVER);
this.chatView.vbarPolicyProperty().set(ScrollBarPolicy.AS_NEEDED);
/*this.chatView.vvalueProperty().addListener(e -> {
if(this.chatView.getVvalue() != 1) {
System.out.println("Pre: " + this.chatView.getVvalue());
this.chatView.vvalueProperty().set(1);
System.out.println("Post: " + this.chatView.getVvalue());
}
});*/
this.scrollButton.setOnAction(e -> {
scrollToBottom();
});
}
private void initSecondColumn() {
this.secondColumn.setStyle("-fx-background-color: gainsboro");
this.secondColumn.setPrefSize(525, 550);
this.secondColumn.setMinSize(450, 550);
this.secondColumn.setMaxSize(525, 550);
Button dlButton = new Button("Download link:");
dlButton.setStyle("-fx-focus-color: transparent");
dlButton.setOnAction(e -> {
if (!this.dlField.getText().equals(null) || !this.dlField.getText().equals(null)) {
try {
FileHandler.downloadFile(this.window, this.dlField.getText());
} catch (Exception ex) {
ex.printStackTrace();
}
this.dlField.clear();
}
});
this.dlField.setPrefSize(450, 20);
this.dlField.setMinSize(450, 20);
this.dlField.setMaxSize(450, 20);
this.mediaColumn.setFitHeight(475);
this.mediaColumn.setPreserveRatio(true);
this.mediaColumn.setStyle("-fx-border-color: red");
this.mediaColumn.prefWidth(450);
this.mediaColumn.prefHeight(475);
this.mediaColumn.minWidth(450);
this.mediaColumn.minHeight(475);
this.mediaColumn.maxWidth(450);
this.mediaColumn.maxHeight(475);
this.secondColumn.getChildren().addAll(dlButton, this.dlField, mediaColumn);
}
private void initUsersArea() {
this.usersArea.setPrefSize(500, 75);
this.usersArea.setMinSize(500, 75);
this.usersArea.setMaxSize(500, 75);
this.usersArea.setEditable(false);
this.usersArea.setStyle("-fx-focus-color: transparent; -fx-background-color: gainsboro");
}
public void scrollToBottom() {
Platform.runLater(() -> this.getChatView().vvalueProperty().setValue(1.0));
System.out.println(this.chatView.getVvalue());
}
public MainScreenController(GridPane layout, Stage window, Scene currentScene, Scene nextScene, WindowController windowController) throws URISyntaxException, IOException {
new File(FileHandler.downloadsPath).mkdirs();
this.layout = layout;
this.window = window;
this.initChatView();
FileHandler.readLog(this.getChatBox());
}
private void initUsernameLabel() {
this.usernameLabel = new Label();
this.usernameLabel.setStyle("-fx-border-color: black; -fx-background-color: silver; -fx-focus-color: transparent");
this.usernameLabel.setText(" Logged in as ");
this.usernameLabel.setTextFill(Color.BLUE);
}
private void initLayout() {
this.layout.setPadding(new Insets(10, 10, 10, 10));
this.layout.setVgap(10);
this.layout.setHgap(10);
this.layout.getChildren().addAll(this.firstColumn, this.secondColumn);
GridPane.setColumnIndex(this.firstColumn, 0);
GridPane.setColumnIndex(this.secondColumn, 1);
GridPane.setValignment(secondColumn, VPos.BOTTOM);
this.buttonBox.getChildren().addAll(this.logoutButton, this.scrollButton);
this.firstColumn.getChildren().addAll(this.buttonBox, this.usernameLabel, this.usersArea, this.chatView, this.getChatField());
}
public void initBtn1() {
btn1.setStyle("-fx-focus-color: transparent");
GridPane.setConstraints(btn1, 1, 0);
GridPane.setValignment(btn1, VPos.BASELINE);
this.layout.getChildren().add(btn1);
btn1.addEventHandler(ActionEvent.ACTION, e -> {
boolean b = false;
if (!b) {
audioHandler.startRecording();
b = !b;
} else if (b) {
audioHandler.stopRecording();
b = !b;
}
});
}
public void addMessage(String msg, String color) {
FileHandler.writeToChatLog(msg);
if (!msg.startsWith("*!") && !msg.startsWith("/")) {
Platform.runLater(() -> {
this.getChatBox().addText(new ChatText(msg, color));
this.scrollButton.arm();
this.scrollButton.fire();
});
}
}
private void initChatField() {
this.getChatField().setPrefSize(500, 10);
this.getChatField().setMaxHeight(10);
this.getChatField().autosize();
this.getChatField().setWrapText(true);
this.getChatField().addEventHandler(KeyEvent.KEY_PRESSED, key -> {
if (key.getCode() == KeyCode.ENTER) {
key.consume();
if (this.getChatField().getText().startsWith("/")) {
CommandParser.parse(this.getChatField().getText(), this);
} else {
try {
this.getClient().getClientSendingData().writeUTF(this.getChatField().getText().trim());
this.getChatField().clear();
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
this.getChatField().setStyle("-fx-background-color: gainsboro");
}
private void initLogoutButton() {
this.logoutButton = new Button();
this.logoutButton.setText("Log out");
this.logoutButton.setOnAction(e -> {
try {
this.client.getClientSendingData().writeUTF("*![System] " + SystemInfo.getDate() + ": " + this.client.getClientName() + " has disconnected.");
System.out.println("Logging out.");
window.close();
new ChatClient().start(new Stage());
} catch (Exception ex) {
ex.printStackTrace();
}
});
this.logoutButton.setStyle("-fx-focus-color: transparent");
}
public void initMainScreen() {
initUsernameLabel();
initLogoutButton();
initChatField();
initLayout();
initUsersArea();
initBtn1();
initSecondColumn();
}
public void setUsername(String username) {
this.username = username;
}
public String getUsername() {
return this.username;
}
public Label getUsernameLabel() {
return this.usernameLabel;
}
public GridPane getLayout() {
return this.layout;
}
public void setIsHosting(boolean b) {
this.isHosting = b;
}
public boolean getIsHosting() {
return this.isHosting;
}
public Server getServer() {
return this.server;
}
public void setServer(Server hostServer) {
this.server = hostServer;
}
public Client getClient() {
return this.client;
}
public void setClient(Client client) {
this.client = client;
}
public ScrollPane getChatView() {
return chatView;
}
public void setChatView(ScrollPane chatView) {
this.chatView = chatView;
}
public TextArea getChatField() {
return chatField;
}
public void setChatField(TextArea chatField) {
this.chatField = chatField;
}
public TextArea getUsersArea() {
return this.usersArea;
}
public ChatBox getChatBox() {
return chatBox;
}
public void setChatBox(ChatBox chatBox) {
this.chatBox = chatBox;
}
}
如果您有任何其他一般性建议（我刚刚开始学习 Java），欢迎所有提示。 :)
谢谢！
我发现问题是由于多线程。对于任何感兴趣的人，请尝试在执行 scrollToBottom() 调用的线程上添加一个非常小的 Thread.sleep() ；我选择了 10 毫秒作为似乎可行的最低值。感谢任何试图提供帮助的人。
我将 TextArea 中的文本滚动到底部所做的是，将文本中的插入符号设置为文本的末尾，例如：
textArea.positionCaret(textArea.getText().length());
事实上，为了确保 TextArea 中的文本不会向左水平滚动（例如，当 TextArea 中的最后一行很长时），我将插入符设置在最后一个 "\n " 在文本中，像这样：
String content = textArea.getText();
int indexOfLastLineFeed = content.lastIndexOf("\n");
if (indexOfLastLineFeed == -1)
textArea.positionCaret(content.length());
else
textArea.positionCaret(Math.min(indexOfLastLineFeed + 1, content.length()));
我在将 ScrollPane 与 MasonryPane（来自 JFoenix）一起使用时也发生了这个错误。我找到的解决方案是调用滚动窗格及其内容的 layout() 方法。层次结构：ScrollPane -> MasonryPane`
masonryPane.getChildren().addListener((ListChangeListener<Node>) c -> {
masonryPane.layout();
scrollPane.layout();
scrollPane.setVvalue(1.0f);
});
我一直在为我和一些朋友开发一个小型聊天客户端，同时自学 Java 和 JFX 8。不幸的是，出于某种原因，我无法以编程方式滚动到聊天消息所在的 ScrollPane 底部。
我有一个名为 scrollToBottom() 的方法，它执行以下代码：
public void scrollToBottom() {
Platform.runLater(() -> this.getChatView().vvalueProperty().setValue(1.0));
}
我有一个按钮可以使用此方法滚动到底部，但任何其他编程方法（甚至从其他方法触发按钮）都无法正确更新滚动窗格的滚动条。但是，当我在假定滚动后在滚动窗格上调用 getVvalue() 时，它 returns 是我试图让它滚动的正确值。滚动窗格只是没有滚动到假定的值。
下面是应用程序中唯一真正相关的 class - ChatBox 类型只是 VBox 的扩展，它仅使用扩展类型的文本。
public class MainScreenController {
//Lists
//Buttons
private Button logoutButton;
private Button btn1 = new Button("Test Button");
private Button scrollButton = new Button("Scroll Button");
//Numbers
//Booleans
private boolean isHosting;
//Strings
private String username = "";
//Scene
private Stage window;
private GridPane layout = new GridPane();
//Other Objects
private TextArea chatField = new TextArea();
private Label usernameLabel;
private TextArea usersArea = new TextArea("Connected users: ");
private VBox firstColumn = new VBox(10);
private VBox secondColumn = new VBox(10);
private ImageView mediaColumn = new ImageView();
private Server server = new Server();
private Client client = new Client();
private TextField dlField = new TextField();
private AudioHandler audioHandler = new AudioHandler();
private ChatBox chatBox = new ChatBox();
private ScrollPane chatView = new ScrollPane(this.chatBox);
private HBox buttonBox = new HBox(10);
private void initChatView() {
this.getChatView().setMinSize(500, 500);
this.getChatView().setPrefSize(500, 500);
this.getChatView().setMaxSize(500, 500);
this.getChatView().setStyle("-fx-focus-color: transparent; -fx-background-color: gainsboro");
this.chatView.hbarPolicyProperty().set(ScrollBarPolicy.NEVER);
this.chatView.vbarPolicyProperty().set(ScrollBarPolicy.AS_NEEDED);
/*this.chatView.vvalueProperty().addListener(e -> {
if(this.chatView.getVvalue() != 1) {
System.out.println("Pre: " + this.chatView.getVvalue());
this.chatView.vvalueProperty().set(1);
System.out.println("Post: " + this.chatView.getVvalue());
}
});*/
this.scrollButton.setOnAction(e -> {
scrollToBottom();
});
}
private void initSecondColumn() {
this.secondColumn.setStyle("-fx-background-color: gainsboro");
this.secondColumn.setPrefSize(525, 550);
this.secondColumn.setMinSize(450, 550);
this.secondColumn.setMaxSize(525, 550);
Button dlButton = new Button("Download link:");
dlButton.setStyle("-fx-focus-color: transparent");
dlButton.setOnAction(e -> {
if (!this.dlField.getText().equals(null) || !this.dlField.getText().equals(null)) {
try {
FileHandler.downloadFile(this.window, this.dlField.getText());
} catch (Exception ex) {
ex.printStackTrace();
}
this.dlField.clear();
}
});
this.dlField.setPrefSize(450, 20);
this.dlField.setMinSize(450, 20);
this.dlField.setMaxSize(450, 20);
this.mediaColumn.setFitHeight(475);
this.mediaColumn.setPreserveRatio(true);
this.mediaColumn.setStyle("-fx-border-color: red");
this.mediaColumn.prefWidth(450);
this.mediaColumn.prefHeight(475);
this.mediaColumn.minWidth(450);
this.mediaColumn.minHeight(475);
this.mediaColumn.maxWidth(450);
this.mediaColumn.maxHeight(475);
this.secondColumn.getChildren().addAll(dlButton, this.dlField, mediaColumn);
}
private void initUsersArea() {
this.usersArea.setPrefSize(500, 75);
this.usersArea.setMinSize(500, 75);
this.usersArea.setMaxSize(500, 75);
this.usersArea.setEditable(false);
this.usersArea.setStyle("-fx-focus-color: transparent; -fx-background-color: gainsboro");
}
public void scrollToBottom() {
Platform.runLater(() -> this.getChatView().vvalueProperty().setValue(1.0));
System.out.println(this.chatView.getVvalue());
}
public MainScreenController(GridPane layout, Stage window, Scene currentScene, Scene nextScene, WindowController windowController) throws URISyntaxException, IOException {
new File(FileHandler.downloadsPath).mkdirs();
this.layout = layout;
this.window = window;
this.initChatView();
FileHandler.readLog(this.getChatBox());
}
private void initUsernameLabel() {
this.usernameLabel = new Label();
this.usernameLabel.setStyle("-fx-border-color: black; -fx-background-color: silver; -fx-focus-color: transparent");
this.usernameLabel.setText(" Logged in as ");
this.usernameLabel.setTextFill(Color.BLUE);
}
private void initLayout() {
this.layout.setPadding(new Insets(10, 10, 10, 10));
this.layout.setVgap(10);
this.layout.setHgap(10);
this.layout.getChildren().addAll(this.firstColumn, this.secondColumn);
GridPane.setColumnIndex(this.firstColumn, 0);
GridPane.setColumnIndex(this.secondColumn, 1);
GridPane.setValignment(secondColumn, VPos.BOTTOM);
this.buttonBox.getChildren().addAll(this.logoutButton, this.scrollButton);
this.firstColumn.getChildren().addAll(this.buttonBox, this.usernameLabel, this.usersArea, this.chatView, this.getChatField());
}
public void initBtn1() {
btn1.setStyle("-fx-focus-color: transparent");
GridPane.setConstraints(btn1, 1, 0);
GridPane.setValignment(btn1, VPos.BASELINE);
this.layout.getChildren().add(btn1);
btn1.addEventHandler(ActionEvent.ACTION, e -> {
boolean b = false;
if (!b) {
audioHandler.startRecording();
b = !b;
} else if (b) {
audioHandler.stopRecording();
b = !b;
}
});
}
public void addMessage(String msg, String color) {
FileHandler.writeToChatLog(msg);
if (!msg.startsWith("*!") && !msg.startsWith("/")) {
Platform.runLater(() -> {
this.getChatBox().addText(new ChatText(msg, color));
this.scrollButton.arm();
this.scrollButton.fire();
});
}
}
private void initChatField() {
this.getChatField().setPrefSize(500, 10);
this.getChatField().setMaxHeight(10);
this.getChatField().autosize();
this.getChatField().setWrapText(true);
this.getChatField().addEventHandler(KeyEvent.KEY_PRESSED, key -> {
if (key.getCode() == KeyCode.ENTER) {
key.consume();
if (this.getChatField().getText().startsWith("/")) {
CommandParser.parse(this.getChatField().getText(), this);
} else {
try {
this.getClient().getClientSendingData().writeUTF(this.getChatField().getText().trim());
this.getChatField().clear();
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
this.getChatField().setStyle("-fx-background-color: gainsboro");
}
private void initLogoutButton() {
this.logoutButton = new Button();
this.logoutButton.setText("Log out");
this.logoutButton.setOnAction(e -> {
try {
this.client.getClientSendingData().writeUTF("*![System] " + SystemInfo.getDate() + ": " + this.client.getClientName() + " has disconnected.");
System.out.println("Logging out.");
window.close();
new ChatClient().start(new Stage());
} catch (Exception ex) {
ex.printStackTrace();
}
});
this.logoutButton.setStyle("-fx-focus-color: transparent");
}
public void initMainScreen() {
initUsernameLabel();
initLogoutButton();
initChatField();
initLayout();
initUsersArea();
initBtn1();
initSecondColumn();
}
public void setUsername(String username) {
this.username = username;
}
public String getUsername() {
return this.username;
}
public Label getUsernameLabel() {
return this.usernameLabel;
}
public GridPane getLayout() {
return this.layout;
}
public void setIsHosting(boolean b) {
this.isHosting = b;
}
public boolean getIsHosting() {
return this.isHosting;
}
public Server getServer() {
return this.server;
}
public void setServer(Server hostServer) {
this.server = hostServer;
}
public Client getClient() {
return this.client;
}
public void setClient(Client client) {
this.client = client;
}
public ScrollPane getChatView() {
return chatView;
}
public void setChatView(ScrollPane chatView) {
this.chatView = chatView;
}
public TextArea getChatField() {
return chatField;
}
public void setChatField(TextArea chatField) {
this.chatField = chatField;
}
public TextArea getUsersArea() {
return this.usersArea;
}
public ChatBox getChatBox() {
return chatBox;
}
public void setChatBox(ChatBox chatBox) {
this.chatBox = chatBox;
}
}
如果您有任何其他一般性建议（我刚刚开始学习 Java），欢迎所有提示。 :) 谢谢！
我发现问题是由于多线程。对于任何感兴趣的人，请尝试在执行 scrollToBottom() 调用的线程上添加一个非常小的 Thread.sleep() ；我选择了 10 毫秒作为似乎可行的最低值。感谢任何试图提供帮助的人。
我将 TextArea 中的文本滚动到底部所做的是，将文本中的插入符号设置为文本的末尾，例如：
textArea.positionCaret(textArea.getText().length());
事实上，为了确保 TextArea 中的文本不会向左水平滚动（例如，当 TextArea 中的最后一行很长时），我将插入符设置在最后一个 "\n " 在文本中，像这样：
String content = textArea.getText();
int indexOfLastLineFeed = content.lastIndexOf("\n");
if (indexOfLastLineFeed == -1)
textArea.positionCaret(content.length());
else
textArea.positionCaret(Math.min(indexOfLastLineFeed + 1, content.length()));
我在将 ScrollPane 与 MasonryPane（来自 JFoenix）一起使用时也发生了这个错误。我找到的解决方案是调用滚动窗格及其内容的 layout() 方法。层次结构：ScrollPane -> MasonryPane`
masonryPane.getChildren().addListener((ListChangeListener<Node>) c -> {
masonryPane.layout();
scrollPane.layout();
scrollPane.setVvalue(1.0f);
});