如果使用JPanels，那麼由視口占據的JPanel應該覆蓋JPanel類並應實現Scrollable接口，爲覆蓋的方法返回適當的值，特別是getPreferredScrollableViewportSize()方法。儘管我的錢，我寧願使用JList，並使用適當的渲染器，而不是JPanels，然後通過其setVisibleRowCount(...)方法設置我的JLists visibleRowCount。
例如：
實例編輯到現在顯示JList和一個滾動的JPanel兩個
import java.awt.Component;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.Rectangle;
import javax.swing.*;
@SuppressWarnings("serial")
public class VisibleRows extends JPanel {
private DefaultListModel<Datum> dataModel = new DefaultListModel<>();
private JList<Datum> datumList = new JList<>(dataModel);
public VisibleRows() {
DataPanel dataPanel = new DataPanel(8);
for (int i = 0; i < 200; i++) {
String name = "John Smith " + i;
int value = i;
Datum datum = new Datum(name, value);
dataPanel.addDatum(datum);
dataModel.addElement(datum);
}
JScrollPane scrollPane1 = new JScrollPane(dataPanel);
scrollPane1.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
add(scrollPane1);
datumList.setVisibleRowCount(8);
datumList.setCellRenderer(new DatumRenderer());
datumList.setPrototypeCellValue(new Datum("XXXXXXXXXXX", 200));
JScrollPane scrollPane2 = new JScrollPane(datumList);
scrollPane2.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
add(scrollPane2);
}
private static void createAndShowGui() {
JFrame frame = new JFrame("VisibleRows");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new VisibleRows());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
@SuppressWarnings("serial")
class DatumRenderer extends DatumPanel implements ListCellRenderer<Datum> {
@Override
public Component getListCellRendererComponent(JList<? extends Datum> list, Datum value, int index,
boolean isSelected, boolean cellHasFocus) {
setDatum(value);
return this;
}
}
@SuppressWarnings("serial")
class DataPanel extends JPanel implements Scrollable {
private int visibleRowCount = 1;
public DataPanel(int visibleRowCount) {
this.visibleRowCount = visibleRowCount;
setLayout(new GridLayout(0, 1));
}
public void addDatum(Datum datum) {
add(new DatumPanel(datum));
}
@Override
public Dimension getPreferredScrollableViewportSize() {
if (getComponentCount() > 0) {
JComponent comp = (JComponent) getComponents()[0];
int width = getPreferredSize().width;
int height = visibleRowCount * comp.getPreferredSize().height;
Dimension d = new Dimension(width, height);
System.out.println(d);
return d;
} else {
return new Dimension(0, 0);
}
}
@Override
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
if (getComponentCount() > 0) {
JComponent comp = (JComponent) getComponents()[0];
Dimension d = comp.getPreferredSize();
if (orientation == SwingConstants.VERTICAL) {
return d.height;
} else {
return d.width;
}
}
return 0;
}
@Override
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
if (getComponentCount() > 0) {
JComponent comp = (JComponent) getComponents()[0];
Dimension d = comp.getPreferredSize();
if (orientation == SwingConstants.VERTICAL) {
return visibleRowCount * d.height;
} else {
return d.width;
}
}
return 0;
}
@Override
public boolean getScrollableTracksViewportWidth() {
return true;
}
@Override
public boolean getScrollableTracksViewportHeight() {
return false;
}
}
@SuppressWarnings("serial")
class DatumPanel extends JPanel {
private static final int GBC_I = 3;
private Datum datum;
private JLabel nameLabel = new JLabel();
private JLabel valueLabel = new JLabel();
public DatumPanel() {
setLayout(new GridBagLayout());
add(new JLabel("Name:"), createGbc(0, 0));
add(nameLabel, createGbc(1, 0));
add(new JLabel("Value:"), createGbc(0, 1));
add(valueLabel, createGbc(1, 1));
}
public DatumPanel(Datum datum) {
this();
setDatum(datum);
}
public final void setDatum(Datum datum) {
this.datum = datum;
nameLabel.setText(datum.getName());
valueLabel.setText("" + datum.getValue());
}
public Datum getDatum() {
return datum;
}
private GridBagConstraints createGbc(int x, int y) {
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = x;
gbc.gridy = y;
gbc.insets = new Insets(GBC_I, GBC_I, GBC_I, GBC_I);
gbc.insets.left = x != 0 ? 3 * GBC_I : GBC_I;
gbc.weightx = 0.0;
gbc.weighty = 0.0;
return gbc;
}
}
class Datum {
private String name;
private int value;
public Datum(String name, int value) {
this.name = name;
this.value = value;
}
public String getName() {
return name;
}
public int getValue() {
return value;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("Name: " + name + "\n");
sb.append("Value: " + value);
return super.toString();
}
}
請參閱編輯回答 –
'我嘗試了使用JScrollPanes和JPanels與GridLayout和GridBagLayout的組合，以及調用setPreferedSize和setMinimumSize都沒有成功。 - 不要對'setPreferredSize（） 。這將防止滾動工作！只需將子面板添加到父面板，然後使用父面板創建JScrollPane，然後將該scrollPane添加到該面板。 – camickr
查看最新的編輯，現在也顯示JList解決方案。 –