Question

我有JFrame，其中包含JPanel，其中包含JScrollPane，其中包含另一个JPanel，其中包含两个组件（JPanels）。出于某种原因，当我使用WindowBuilder的预览选项查看框架时，JScrollPane会显示水平滚动条，但是当我编译并运行应用程序时，它并没有＆＃ 39;吨。这是它的样子：

来自预览选项：

编译时：

enter image description here

这是我的代码：

package home;

import java.awt.EventQueue;

import javax.swing.JFrame;

import java.awt.SystemColor;

import javax.swing.JPanel;
import javax.swing.SpringLayout;
import javax.swing.UIManager;

import net.miginfocom.swing.MigLayout;

import javax.swing.JLabel;
import javax.swing.SwingConstants;

import java.awt.Component;
import java.awt.BorderLayout;
import java.awt.Frame;

import com.jgoodies.forms.layout.FormLayout;
import com.jgoodies.forms.layout.ColumnSpec;
import com.jgoodies.forms.layout.RowSpec;
import com.jgoodies.forms.factories.FormFactory;

import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.JButton;
import javax.swing.LayoutStyle.ComponentPlacement;
import javax.swing.UnsupportedLookAndFeelException;

import java.awt.Font;

import javax.swing.BoxLayout;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.Color;
import java.awt.Dimension;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import javax.swing.ImageIcon;
import javax.swing.JScrollPane;
import javax.swing.border.EtchedBorder;
import javax.swing.border.LineBorder;
import javax.swing.ScrollPaneConstants;

public class AtmManeger implements Serializable  {

    private JFrame frmAtmManeger;
    public int NumOfOpenAtmMachines = 0;
    private final AtmManeger frame = this;
    private ArrayList<ATMmachine> ATMs = new ArrayList<ATMmachine>();//Array list of all the ATM machines that were opened
    private AtmAccountDataBase atmDataBase = new AtmAccountDataBase();
    private JLabel contLabel = null;
    /**
     * Launch the application.
     */
    public static void main(String[] args) {

        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    AtmManeger window = new AtmManeger();
                    window.frmAtmManeger.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

    }

    /**
     * Create the application.
     */
    public AtmManeger getFrame() {
        return this.frame;
    }
    public AtmManeger() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (ClassNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (InstantiationException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IllegalAccessException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (UnsupportedLookAndFeelException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        frmAtmManeger = new JFrame();
        frmAtmManeger.setMinimumSize(new Dimension(615, 420));
        frmAtmManeger.getContentPane().setBackground(SystemColor.activeCaption);
        JPanel mainPanel = new JPanel();
        mainPanel.setPreferredSize(new Dimension(10, 10));
        frmAtmManeger.setContentPane(mainPanel);
        JScrollPane scrollPane = new JScrollPane();
        mainPanel.add(scrollPane, BorderLayout.CENTER);
        JPanel subPanel = new JPanel();
        subPanel.setSize(new Dimension(1190, 350));
        subPanel.setBackground(SystemColor.activeCaption);
        subPanel.setPreferredSize(new Dimension(1190, 350));
        scrollPane.setViewportView(subPanel);
        subPanel.setLayout(new MigLayout("", "[50.00%,grow][50.00%,grow]", "[grow]"));
        JPanel panel = new JPanel();
        subPanel.add(panel,"cell 0 0,grow");
        panel.setBorder(null);
        panel.setBackground(SystemColor.textHighlight);

        panel.setLayout(new MigLayout("", "[100.00%,grow]", "[71px][13.54%][10.09%][41px][][grow]"));

        JPanel panel_1 = new JPanel();
        subPanel.add(panel_1, "cell 1 0,grow");
        frmAtmManeger.setTitle("ATM Maneger");
        frmAtmManeger.setBounds(700, 400, 609, 420);
        frmAtmManeger.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

我制作的另一个应用程序与此非常相似，只有一个应用程序JFrame。我无法找到此代码与上述代码之间的任何差异。代码：

package home;

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.border.EmptyBorder;
import javax.swing.JScrollPane;

import java.awt.Color;
import java.awt.FlowLayout;

import net.miginfocom.swing.MigLayout;

import java.awt.Dimension;
import javax.swing.JLabel;
import javax.swing.JButton;

public class test02 extends JFrame {

    private JPanel contentPane;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    test02 frame = new test02();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public test02() {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e) {
            // Handle exception
        }
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 432, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        JScrollPane scrollPane = new JScrollPane();
        contentPane.add(scrollPane, BorderLayout.CENTER);

        JPanel panel = new JPanel();
        panel.setPreferredSize(new Dimension(800, 220));
        panel.setBackground(Color.RED);
        scrollPane.setViewportView(panel);
        panel.setLayout(new MigLayout("", "[50.00%,grow][50.00%,grow]", "[grow]"));

        JPanel panel_1 = new JPanel();
        panel.add(panel_1, "cell 0 0,grow");
        panel_1.setLayout(new MigLayout("", "[][][][][][][]", "[][][][][][]"));

        JLabel lblNewLabel = new JLabel("New label");
        panel_1.add(lblNewLabel, "cell 2 1");

        JButton btnNewButton_1 = new JButton("New button");
        panel_1.add(btnNewButton_1, "cell 3 3");

        JButton btnNewButton = new JButton("New button");
        panel_1.add(btnNewButton, "cell 2 5");

        JLabel lblNewLabel_1 = new JLabel("New label");
        panel_1.add(lblNewLabel_1, "cell 6 5");

        JPanel panel_2 = new JPanel();
        panel.add(panel_2, "cell 1 0,grow");
    }

}

所以这可能只是一个愚蠢的错误，但它是什么？

Answer 1

我没有看到您更改滚动条策略。由于没有溢出，如果不更改该设置，您将看不到滚动条。

尝试：

scrollbar.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

Answer 2

我已根据要求编写了一个显示面板的程序。

enter image description here

<强>代码：

private void createUI() {
        JFrame frame = new JFrame();
        JPanel panel = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JScrollPane pane = new JScrollPane();

        JPanel leftPnl = new JPanel(new BorderLayout());
        JPanel rightPnl = new JPanel(new BorderLayout());

        leftPnl.add(new JLabel("Left"), BorderLayout.CENTER);
        leftPnl.setBorder(new LineBorder(Color.black, 5));
        leftPnl.setPreferredSize(new Dimension(400, 400));
        rightPnl.add(new JLabel("Right"), BorderLayout.CENTER);
        rightPnl.setBorder(new LineBorder(Color.black, 5));
        rightPnl.setPreferredSize(new Dimension(400, 400));

        panel.add(leftPnl);
        panel.add(rightPnl);
        panel.add(pane);

        frame.setPreferredSize(new Dimension(400, 400));
        frame.setTitle("ScrollPane Example");
        frame.add(new JScrollPane(panel));
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

JScrollPane不工作/显示滚动条

2 个答案: