Detailed instructions for using JScrollPane in Java

Preface

In JavaJScrollPaneis a container component in the Swing component library that provides a view with a scroll bar to display large components or content that exceeds its own display area. useJScrollPaneIt allows users to view all content through the scroll bar without changing the window size.

Here are some things to doJScrollPaneA detailed description of the key points and how to use it in a Java Swing application:

Create a JScrollPane

To create aJScrollPane, you will usually associate it with another component, such asJTable、JTextArea、JListOr any otherComponent. Here is a simple example showing how toJTextAreaCreate a scroll pane:

import .*;

public class ScrollPaneExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JScrollPane Example");
        JTextArea textArea = new JTextArea(20, 20);
        JScrollPane scrollPane = new JScrollPane(textArea);

        ().add(scrollPane);
        (300, 300);
        (JFrame.EXIT_ON_CLOSE);
        (true);
    }
}

In this example,JTextAreaComponents are added toJScrollPanein, and the wholeJScrollPaneAdded toJFramein the content panel.

JScrollPane constructor

JScrollPaneThere are several constructors that you can choose to use according to your needs:

JScrollPane(): Create a without any contentJScrollPane。
JScrollPane(Component view): Create a component containing the specifiedJScrollPane。
JScrollPane(int vsbPolicy, int hsbPolicy): Create aJScrollPane, where you can specify display strategies for vertical and horizontal scroll bars.
JScrollPane(Component view, int vsbPolicy, int hsbPolicy): Create a component containing the specifiedJScrollPane, and the display policy of the scroll bar can be specified.

The display strategy of the scroll bar can be one of the following three:

ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED
ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS
ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER

(The same strategy applies to horizontal scroll bars)

Scrollbar strategy

You can set the display strategy of the scroll bar to control the display and hidden behavior of the scroll bar when the content size changes. This can be calledsetVerticalScrollBarPolicyandsetHorizontalScrollBarPolicyMethod to implement.

Viewport

JScrollPaneThe viewport is the actual area where the content is displayed. You can passgetViewportMethods to obtain the viewport and operate on it. For example, you can set the view size of the viewport or update the content displayed by the viewport.

Listen to scroll events

You canJScrollPaneAdd a scroll listener to scroll events. Usually this is by adding aAdjustmentListenerTo the scroll bar model to implement.

().addAdjustmentListener(new AdjustmentListener() {
    public void adjustmentValueChanged(AdjustmentEvent e) {
        // Handle scrolling events    }
});

Other customization options

You can passsetRowHeaderView(Component view)forJScrollPaneAdd a line header.
usesetColumnHeaderView(Component view)You can add column headers.
passsetCorner(String key, Component corner)Corner components can be added to the scroll pane, usually used for decoration.
usegetHorizontalScrollBarandgetVerticalScrollBarThe method can obtain the scrollbar component for further customization.

JScrollPaneIt is a very flexible component that provides a variety of configuration options to meet different layout needs and optimization of user experience. Use it reasonably when designing complex user interfacesJScrollPaneCan improve the usability of the application.

The following provides several different scenarios for useJScrollPaneExample.

Example 1: JScrollPane contains a JList

import .*;

public class JListScrollPaneExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JList inside JScrollPane Example");
        String[] listItems = {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"};
        JList<String> list = new JList<>(listItems);

        JScrollPane scrollPane = new JScrollPane(list);
        (scrollPane);
        (200, 200);
        (JFrame.EXIT_ON_CLOSE);
        (true);
    }
}

In this example, we created aJList, which contains some list items and put thisJListPut it inJScrollPanemiddle. When the list item exceedsJListThe scroll bar will automatically appear when viewing area.

Example 2: JScrollPane contains a JTable

import .*;
import ;

public class JTableScrollPaneExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JTable inside JScrollPane Example");
        DefaultTableModel model = new DefaultTableModel(new Object[]{"Column 1", "Column 2", "Column 3"}, 0);
        JTable table = new JTable(model);

        // Add some data to the table        (new Object[]{"Value 1", "Value 2", "Value 3"});
        (new Object[]{"Value 4", "Value 5", "Value 6"});
        (new Object[]{"Value 7", "Value 8", "Value 9"});

        JScrollPane scrollPane = new JScrollPane(table);
        (scrollPane);
        (300, 150);
        (JFrame.EXIT_ON_CLOSE);
        (true);
    }
}

In this example, we created aJTableAnd added a model to it. Then, we add row data to this model.JTablePlaced onJScrollPane, so that the data can be viewed scrollly when it exceeds the display range.

Example 3: JScrollPane contains a larger JPanel

import .*;

public class JPanelScrollPaneExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JPanel inside JScrollPane Example");
        JPanel panel = new JPanel();
        (new Dimension(1000, 1000)); // Set the preferred size of JPanel
        // Add some components to JPanel        for (int i = 1; i &lt;= 50; i++) {
            (new JButton("Button " + i));
        }

        JScrollPane scrollPane = new JScrollPane(panel,
                JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

        (scrollPane);
        (300, 300);
        (JFrame.EXIT_ON_CLOSE);
        (true);
    }
}

This example demonstrates how to convert a larger oneJPanelPut inJScrollPanemiddle.JPanelThe preferred size is set to 1000x1000 pixels, which is usually beyond the display range of most monitors.JScrollPaneVertical and horizontal scroll bars are provided, and users can scroll to view the entire panel.

Example 4: Dynamically update content in JScrollPane

import .*;
import .*;
import .*;

public class JScrollPaneDynamicUpdateExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JScrollPane Dynamic Update Example");
        JTextArea textArea = new JTextArea(20, 20);
        JScrollPane scrollPane = new JScrollPane(textArea);

        JButton addButton = new JButton("Add Text");
        (new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                ("Some new text\n"); // Add text to JTextArea            }
        });

        (new BorderLayout());
        (scrollPane, );
        (addButton, );
        
        (300, 300);
        (JFrame.EXIT_ON_CLOSE);
        (true);
    }
}

In this example, we created aJTextAreaAnd put it inJScrollPanemiddle. In this example, we created aJTextAreaAnd put it inJScrollPanemiddle. At the same time, we provide a button that will refer to theJTextAreaAdd new text content to . Because the text content may exceedJTextAreaThe current view area, soJScrollPaneA scroll bar will be automatically provided so that the user can scroll to view all content.

Summarize

This is the end of this article about the detailed instructions on the use of JScrollPane in Java. For more information about JScrollPane related to Java, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!