java 爪哇。文本区域中的 GUI WindowBuilder 滚动条不起作用

Java. GUI WindowBuilder scroll bar in text area doesn't work

提问by

I don't know why my scroll bar in text area doesn't work. I found many solutions in internet, but no 1 helped for me.

我不知道为什么我在文本区域中的滚动条不起作用。我在互联网上找到了很多解决方案，但没有一个对我有帮助。

textArea1 = new JTextArea();
textArea1.setBounds(13, 28, 182, 199);
panel.add(textArea1);

JScrollBar scrollBar = new JScrollBar();
scrollBar.setBounds(205, 1, 17, 242);
panel.add(scrollBar);

I found that can't be Panel's layout Absolute, if I change It to Group layout the same. What's wrong? Could you help me? Thank you.

我发现不能是 Panel 的布局 Absolute，如果我将它更改为 Group 布局相同。怎么了？你可以帮帮我吗？谢谢你。

UPDATED:

更新：

package lt.kvk.i3_2.kalasnikovas_stanislovas;

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import javax.swing.JTextPane;
import javax.swing.DropMode;
import javax.swing.JFormattedTextField;
import java.awt.Component;
import javax.swing.Box;
import java.awt.Dimension;
import javax.swing.JTextField;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Toolkit;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.JMenuItem;
import javax.swing.LayoutStyle.ComponentPlacement;
import javax.swing.ImageIcon;
import javax.swing.JDesktopPane;
import java.awt.SystemColor;
import java.awt.Font;
import javax.swing.border.BevelBorder;
import javax.swing.border.EtchedBorder;
import javax.swing.JScrollBar;
import java.awt.Color;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;

import javax.swing.JLabel;
import javax.swing.JToolBar;

public class KDVizualizuotas {

    private JFrame frmInformacijaApieMuzikos;
    private JTextField txtStilius;
    private JTextArea textArea1;

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

    /**
     * Create the application.
     */
    public KDVizualizuotas() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frmInformacijaApieMuzikos = new JFrame();
        frmInformacijaApieMuzikos.setResizable(false);
        frmInformacijaApieMuzikos.setIconImage(Toolkit.getDefaultToolkit().getImage(KDVizualizuotas.class.getResource("/lt/kvk/i3_2/kalasnikovas_stanislovas/resources/Sidebar-Music-Blue-icon.png")));
        frmInformacijaApieMuzikos.setTitle("Muzikos stiliai");
        frmInformacijaApieMuzikos.setBounds(100, 100, 262, 368);
        frmInformacijaApieMuzikos.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        txtStilius = new JTextField();
        txtStilius.setBounds(10, 34, 128, 20);
        txtStilius.setColumns(10);

        JButton btnIekoti = new JButton("Ie\u0161koti");
        btnIekoti.setBounds(146, 36, 89, 19);
        btnIekoti.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
        //      textArea1.append(txtStilius.getText()+"\n");
        //      txtStilius.getText();



                 Scanner input = new Scanner(System.in);
                    try {
                        FileReader fr = new FileReader("src/lt/kvk/i3_2/kalasnikovas_stanislovas/Stiliai.txt");
                        BufferedReader br = new BufferedReader(fr);
                        String stiliuSarasas;
                        while((stiliuSarasas = br.readLine()) != null) {
                            System.out.println(stiliuSarasas);
                            textArea1.append(stiliuSarasas+"\n");
                            }
                        fr.close();
                        }
                    catch (IOException e) {
                        System.out.println("Error:" + e.toString());
                    }





            }
        });

        JPanel panel = new JPanel();
        panel.setBounds(10, 65, 224, 243);
        panel.setBorder(new EtchedBorder(EtchedBorder.LOWERED, null, null));
        panel.setBackground(SystemColor.text);

        JLabel lblveskiteMuzikosStili = new JLabel("\u012Eveskite muzikos stili\u0173:");
        lblveskiteMuzikosStili.setBounds(10, 14, 222, 14);
        frmInformacijaApieMuzikos.getContentPane().setLayout(null);
        panel.setLayout(null);
        frmInformacijaApieMuzikos.getContentPane().add(panel);


        JLabel lblInformacijaApieMuzikos = new JLabel("Informacija apie muzikos stili\u0173:");
        lblInformacijaApieMuzikos.setBounds(12, 3, 190, 14);
        panel.add(lblInformacijaApieMuzikos);

        textArea1 = new JTextArea();
        textArea1.setBounds(13, 28, 182, 199);
        panel.add(textArea1);

        JScrollBar scrollBar = new JScrollBar();
        scrollBar.setBounds(205, 1, 17, 242);
        panel.add(scrollBar);
        frmInformacijaApieMuzikos.getContentPane().add(txtStilius);
        frmInformacijaApieMuzikos.getContentPane().add(btnIekoti);
        frmInformacijaApieMuzikos.getContentPane().add(lblveskiteMuzikosStili);

        JMenuBar menuBar = new JMenuBar();
        frmInformacijaApieMuzikos.setJMenuBar(menuBar);

        JMenu mnFile = new JMenu("File");
        menuBar.add(mnFile);

        JMenuItem mntmExit = new JMenuItem("Exit");
        mntmExit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                System.exit(0);             
            }

        });
        mntmExit.setIcon(new ImageIcon(KDVizualizuotas.class.getResource("/lt/kvk/i3_2/kalasnikovas_stanislovas/resources/exitas.png")));
        mnFile.add(mntmExit);

        JMenu mnEdit = new JMenu("Edit");
        menuBar.add(mnEdit);

        JMenu mnHelp = new JMenu("Help");
        menuBar.add(mnHelp);

        JMenuItem mntmHelp = new JMenuItem("Help");
        mnHelp.add(mntmHelp);

        JMenu mnAbout = new JMenu("About");
        menuBar.add(mnAbout);

        JMenuItem mntmAbout = new JMenuItem("About");
        mntmAbout.setIcon(new ImageIcon(KDVizualizuotas.class.getResource("/lt/kvk/i3_2/kalasnikovas_stanislovas/resources/questionmark.png")));
        mnAbout.add(mntmAbout);
    }
}

采纳答案by MadProgrammer

You need to add the component you want to be contained within the scroll pane to it.

您需要将要包含在滚动窗格中的组件添加到其中。

You can do this via the JScrollPane's constructor or JScrollPane#setViewportViewmethod

您可以通过JScrollPane的构造函数或JScrollPane#setViewportView方法执行此操作

public class ScrollPaneTest {

  public static void main(String[] args) {
    new ScrollPaneTest();
  }

  public ScrollPaneTest() {
    EventQueue.invokeLater(new Runnable() {
      @Override
      public void run() {
        try {
          UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception ex) {
        }

        JPanel bigPane = new JPanel();
        bigPane.setBackground(Color.BLUE);
        // This is not recommended, but is used for demonstration purposes
        bigPane.setPreferredSize(new Dimension(1024, 768)); 

        JScrollPane scrollPane = new JScrollPane(bigPane);
        scrollPane.setPreferredSize(new Dimension(400, 400));

        JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(scrollPane);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
      }
    });
  }
}

Updated with proper layout

更新了适当的布局

You should avoid nullor absolute layouts, they will only hurt you in the long wrong.

您应该避免null或绝对布局，它们只会在长期错误中伤害您。

You may also find How to use Scroll Panesof use

您还可以找到如何使用滚动窗格的使用

public class BadLayout {

  public static void main(String[] args) {
    new BadLayout();
  }

  public BadLayout() {
    EventQueue.invokeLater(new Runnable() {
      @Override
      public void run() {
        try {
          UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception ex) {
        }

        JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new TestPane());
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);

      }
    });
  }

  public class TestPane extends JPanel {

    private JTextField searchField;
    private JButton searchButton;
    private JTextArea searchResults;

    public TestPane() {
      setLayout(new BorderLayout());

      searchResults = new JTextArea();
      searchResults.setLineWrap(true);
      searchResults.setWrapStyleWord(true);
      JScrollPane scrollPane = new JScrollPane(searchResults);

      JPanel results = new JPanel(new BorderLayout());
      results.setBorder(new EmptyBorder(4, 8, 8, 8));
      results.add(scrollPane);
      add(results);

      JPanel search = new JPanel(new GridBagLayout());
      search.setBorder(new EmptyBorder(8, 8, 4, 8));
      searchField = new JTextField(12);
      searchButton = new JButton("Search");

      GridBagConstraints gbc = new GridBagConstraints();
      gbc.gridx = 0;
      gbc.gridy = 0;
      gbc.fill = GridBagConstraints.HORIZONTAL;
      gbc.weightx = 1;
      gbc.insets = new Insets(0, 0, 0, 4);
      search.add(searchField, gbc);

      gbc.insets = new Insets(0, 0, 0, 0);
      gbc.gridx++;
      gbc.fill = GridBagConstraints.NONE;
      gbc.weightx = 0;
      search.add(searchButton, gbc);

      add(search, BorderLayout.NORTH);
    }

    @Override
    public Dimension getPreferredSize() {
      return new Dimension(200, 400);
    }
  }  
}