JavaFX Pagination

落日映苍穹つ 2023-10-15 16:59 13阅读 0赞

The *JavaFX* *Pagination* control enables the user to navigate page by page through content, for instance pages of search results, articles, images or similar types of content. The JavaFX Pagination control is represented by the class `javafx.scene.control.Pagination`. Here is a screenshot of a JavaFX `Pagination` control:

![72e02df7c070483d93298adbd7ed7b10.png][]

### Full Pagination Example ###

Here is first a full Java code example of how to use a JavaFX `Pagination` control:

import javafx.application.Application;
    import javafx.scene.Scene;
    import javafx.scene.control.Label;
    import javafx.scene.control.Pagination;
    import javafx.scene.layout.VBox;
    import javafx.scene.text.Font;
    import javafx.stage.Stage;
    
    public class PaginationExample extends Application {
        public static void main(String[] args) {
            launch(args);
        }
    
        @Override
        public void start(Stage primaryStage) {
            primaryStage.setTitle("JavaFX App");
    
            Pagination pagination = new Pagination();
            pagination.setPageCount(21);
            pagination.setCurrentPageIndex(3);
            pagination.setMaxPageIndicatorCount(3);
    
            pagination.setPageFactory((pageIndex) -> {
    
                Label label1 = new Label("Content for page with index: " + pageIndex);
                label1.setFont(new Font("Arial", 24));
    
                Label label2 = new Label("Main content of the page ...");
    
                return new VBox(label1, label2);
            });
    
            VBox vBox = new VBox(pagination);
            Scene scene = new Scene(vBox, 960, 600);
    
            primaryStage.setScene(scene);
            primaryStage.show();
        }
    }

### Pagination Properties ###

The JavaFX `Pagination` control contains a set of properties that specify how the `Pagination` control is rendered. These properties are:

*  Page count
 *  Current page index
 *  Max number of page indicators

The page count is the total number of pages the user can navigate between. The current page index is the page the user is looking at currently. The maximum number of page indicators is the number of shortcut buttons with page numbers on, which the user can click on to navigate directly to that page.

The effect of all three properties are visible in the screenshot earlier in this tutorial. Here is an example of setting all three properties:

Pagination pagination = new Pagination();
    
    pagination.setPageCount(21);
    pagination.setCurrentPageIndex(3);
    pagination.setMaxPageIndicatorCount(3);

### Pagination Page Factory ###

The JavaFX `Pagination` control needs a page factory set on it to be able to navigate properly through the paged content. The page factory is called when the user navigates to a new page. The page factory component is attached to the `Pagination` control via its `setPageFactory()` method, and must implement the interface `javafx.util.Callback` interface.

Here is first how the `CallBack` interface is defined:

public interface Callback<P,R> {
    
        public R call(P param);
    }

In the `setPageFactory()` method the two type parameters P and R are set to `Integer` (P) and `Node` (R). That means, that the page factory must implement the `Callback<Integer, Node>` interface. Here is an example of an implementation of `Callback<Integer, Node>`:

public static class MyPageFactory implements Callback<Integer, Node> {
        @Override
        public Node call(Integer pageIndex) {
            return new Label("Content for page " + pageIndex);
        }
    }

The `Integer` parameter passed to the `Callback` implementation is the index of the page the page factory should create a `Node` for. The returned `Node` should display the content for the page with the given page index.

Here is an example of setting the page factory on a JavaFX `Pagination` control:

pagination.setPageFactory(new MyPageFactory());

You can also set the page factory on a `Pagination` control using an anonymous `Callback` interface implementation, or using a [Java lambda][] expression. Here is first an example using an anonymous `Callback` implementation:

pagination.setPageFactory(new Callback<Integer, Node>() {
        @Override
        public Node call(Integer pageIndex) {
            return new Label("Content for page " + pageIndex);
        }
    });

And here is an example of setting a `Pagination` page factory using a Java lambda expression:

pagination.setPageFactory((pageIndex) -> {
       return new Label("Content for page " + pageIndex);
    });

And even shorter, using a shorter lambda expression syntax:

pagination.setPageFactory((pageIndex) -> new Label("Content for page " + pageIndex) );

[72e02df7c070483d93298adbd7ed7b10.png]: https://img-blog.csdnimg.cn/72e02df7c070483d93298adbd7ed7b10.png
[Java lambda]: https://jenkov.com/java/lambda-expressions.html