java - JScrollPane 'laggy' 滚动，有很多组件

Question

我有一个 3045 的表格!组件(1015 个标签、1015 个文本字段、1015 个组合框)。所有这些都在 JPanel 中，而 JPanel 在 JScrollPane 中。问题是滚动是“滞后的”。我的 PC 中有 4gb RAM，所以我认为这不是问题所在。怎么了？ 在我的任务管理器中，应用程序使用 ~100mb。

我的代码:

final JScrollPane scrollPane_1 = new JScrollPane();
final JPanel panel = new JPanel();
panel.setLayout(null);
scrollPane_1.setViewportView(panel);
int y =0;
for(int i=0; i<1015;i++)
    {

            JLabel length = new JLabel();
            length.setBounds(10, y, 350, 20);
            length.setFont(new Font("Tahoma", Font.BOLD, 11));
            length.setEnabled(false);
            panel.add(length);
            panel.revalidate();

            JComboBox combo = new JComboBox();
            combo.setModel(new DefaultComboBoxModel(new String[] {"=", "!="}));
            combo.setBounds(10, y + 20, 70, 20);
            panel.add(combo);
            panel.revalidate();

            JTextField text = new JTextField();
            text.setBounds(10 + 80, y + 20, 200, 20);
            panel.add(text);
            panel.revalidate();
}

编辑: 我做了很多测试，我意识到延迟只存在于我使用组合框时，如果我使用例如文本字段而不是组合框，滚动是正常的...

Answer 1

使用布局管理器时，您的代码对我来说似乎并没有那么滞后。请测试一下:

import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridLayout;

import javax.swing.*;

public class Foo2 {
   protected static final int PREF_W = 400;
   protected static final int PREF_H = 400;

   public static void main(String[] args) {
      final JScrollPane scrollPane_1 = new JScrollPane() {
         @Override
         public Dimension getPreferredSize() {
            return new Dimension(PREF_W, PREF_H);
         }
      };
      final JPanel panel = new JPanel();
      panel.setLayout(new GridLayout(0, 1));
      scrollPane_1.setViewportView(panel);
      for (int i = 0; i < 1015; i++) {
         JPanel innerPanel = new JPanel();
         innerPanel.setLayout(new BoxLayout(innerPanel, BoxLayout.LINE_AXIS));

         JLabel length = new JLabel("foo");
         length.setFont(new Font("Tahoma", Font.BOLD, 11));
         length.setEnabled(false);
         innerPanel.add(length);
         innerPanel.add(Box.createHorizontalGlue());

         JComboBox<String> combo = new JComboBox<String>();
         combo.setPrototypeDisplayValue("              ");
         combo.setModel(new DefaultComboBoxModel<String>(new String[] { "=", "!=" }));
         combo.setMaximumSize(combo.getPreferredSize());
         innerPanel.add(combo);

         JTextField text = new JTextField(10);
         JPanel textWrapper = new JPanel();
         textWrapper.add(text);
         innerPanel.add(textWrapper);

         panel.add(innerPanel);
      }
      JFrame frame = new JFrame();
      frame.add(scrollPane_1);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }
}

---

编辑

改用 JTable 怎么样？

import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.*;
import javax.swing.table.DefaultTableModel;

public class Foo3 {
   protected static final int PREF_W = 400;
   protected static final int PREF_H = 400;

   public static void main(String[] args) {
      final JScrollPane scrollPane_1 = new JScrollPane() {
         @Override
         public Dimension getPreferredSize() {
            return new Dimension(PREF_W, PREF_H);
         }
      };
      String[] columnNames = {"Foo", "Bar", "Baz"};
      String[][] data = new String[1015][3];
      for (int i = 0; i < data.length; i++) {
         data[i] = new String[]{"foo", "==", ""};
      }
      DefaultTableModel model = new DefaultTableModel(data, columnNames){
         @Override
         public boolean isCellEditable(int row, int column) {
            return (column != 0);
         }
      };
      JTable table = new JTable(model);
      table.getColumnModel().getColumn(1).setCellEditor(new DefaultCellEditor(
            new JComboBox<String>(new String[]{"==", "!="})));
      final JPanel panel = new JPanel();
      panel.setLayout(new GridLayout(0, 1));
      scrollPane_1.setViewportView(table);

      JFrame frame = new JFrame();
      frame.add(scrollPane_1);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }
}