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== Add your own ListCellRenderer ==

<p>For performance reasons, do not create the renderer in the
getListCellRendererComponent() method.</p>



<source lang="java">
import java.awt.BorderLayout;
import java.awt.ruponent;
import javax.swing.DefaultListCellRenderer;
import javax.swing.DefaultListModel;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.ListCellRenderer;
import javax.swing.border.Border;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;
import javax.swing.border.TitledBorder;
public class SizingSamples {
public static void main(String args[]) {
JFrame frame = new JFrame("Sizing Samples");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
DefaultListModel model = new DefaultListModel();
model.ensureCapacity(100);
for (int i = 0; i < 100; i++) {
model.addElement(Integer.toString(i));
}
JList jlist2 = new JList(model);
ListCellRenderer renderer = new FocusedTitleListCellRenderer();
jlist2.setCellRenderer(renderer);
JScrollPane scrollPane2 = new JScrollPane(jlist2);
frame.add(scrollPane2, BorderLayout.CENTER);
frame.setSize(300, 350);
frame.setVisible(true);
jlist2.ensureIndexIsVisible(50);
}
}
class FocusedTitleListCellRenderer implements ListCellRenderer {
protected static Border noFocusBorder = new EmptyBorder(15, 1, 1, 1);
protected static TitledBorder focusBorder = new TitledBorder(LineBorder.createGrayLineBorder(),
"title");
protected DefaultListCellRenderer defaultRenderer = new DefaultListCellRenderer();
public Component getListCellRendererComponent(JList list, Object value, int index,
boolean isSelected, boolean cellHasFocus) {
JLabel renderer = (JLabel) defaultRenderer.getListCellRendererComponent(list, value, index,
isSelected, cellHasFocus);
renderer.setBorder(cellHasFocus ? focusBorder : noFocusBorder);
return renderer;
}
}</source>



== Change the layout orientation so that its items are displayed top-to-bottom and left-to-right. ==



<source lang="java">
import javax.swing.JList;
import javax.swing.JScrollPane;
public class Main {
public static void main(String[] argv) throws Exception {
String[] items = { "A", "B", "C", "D" };
JList list = new JList(items);
JScrollPane scrollingList = new JScrollPane(list);
// Change orientation to top-to-bottom, left-to-right layout
list.setLayoutOrientation(JList.VERTICAL_WRAP);
}
}</source>



== Creating a Complex ListCellRenderer: font, icon and color ==



<source lang="java">
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.ruponent;
import java.awt.Font;
import java.awt.Graphics;
import javax.swing.DefaultListCellRenderer;
import javax.swing.Icon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.ListCellRenderer;
class ComplexCellRenderer implements ListCellRenderer {
protected DefaultListCellRenderer defaultRenderer = new DefaultListCellRenderer();
public Component getListCellRendererComponent(JList list, Object value, int index,
boolean isSelected, boolean cellHasFocus) {
Font theFont = null;
Color theForeground = null;
Icon theIcon = null;
String theText = null;
JLabel renderer = (JLabel) defaultRenderer.getListCellRendererComponent(list, value, index,
isSelected, cellHasFocus);
if (value instanceof Object[]) {
Object values[] = (Object[]) value;
theFont = (Font) values[0];
theForeground = (Color) values[1];
theIcon = (Icon) values[2];
theText = (String) values[3];
} else {
theFont = list.getFont();
theForeground = list.getForeground();
theText = "";
}
if (!isSelected) {
renderer.setForeground(theForeground);
}
if (theIcon != null) {
renderer.setIcon(theIcon);
}
renderer.setText(theText);
renderer.setFont(theFont);
return renderer;
}
}
public class ComplexRenderingSample {
public static void main(String args[]) {
Object elements[][] = {
{ new Font("Helvetica", Font.PLAIN, 20), Color.RED, new MyIcon(), "A" },
{ new Font("TimesRoman", Font.BOLD, 14), Color.BLUE, new MyIcon(), "A" },
{ new Font("Courier", Font.ITALIC, 18), Color.GREEN, new MyIcon(), "A" },
{ new Font("Helvetica", Font.BOLD | Font.ITALIC, 12), Color.GRAY, new MyIcon(), "A" },
{ new Font("TimesRoman", Font.PLAIN, 32), Color.PINK, new MyIcon(), "A" },
{ new Font("Courier", Font.BOLD, 16), Color.YELLOW, new MyIcon(), "A" },
{ new Font("Helvetica", Font.ITALIC, 8), Color.DARK_GRAY, new MyIcon(), "A" } };
JFrame frame = new JFrame("Complex Renderer");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JList jlist = new JList(elements);
ListCellRenderer renderer = new ComplexCellRenderer();
jlist.setCellRenderer(renderer);
JScrollPane scrollPane = new JScrollPane(jlist);
frame.add(scrollPane, BorderLayout.CENTER);
frame.setSize(300, 200);
frame.setVisible(true);
}
}
class MyIcon implements Icon {
public MyIcon() {
}
public int getIconHeight() {
return 20;
}
public int getIconWidth() {
return 20;
}
public void paintIcon(Component c, Graphics g, int x, int y) {
g.setColor(Color.RED);
g.drawRect(0, 0, 25, 25);
}
}</source>



== Install List cell renderer ==



<source lang="java">
import java.awt.ruponent;
import javax.swing.Icon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.ListCellRenderer;
class MyCellRenderer extends JLabel implements ListCellRenderer {
public MyCellRenderer() {
setOpaque(true);
}
public Component getListCellRendererComponent(JList list, Object value, int index,
boolean isSelected, boolean cellHasFocus) {
setText(value.toString());
if (isSelected) {
setBackground(list.getSelectionBackground());
setForeground(list.getSelectionForeground());
} else {
setBackground(list.getBackground());
setForeground(list.getForeground());
}
return this;
}
}
public class JListRenderer {
public static void main(String[] a) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

JList list = new JList(new String[]{"A","B","C"});
list.setCellRenderer(new MyCellRenderer());
frame.add(new JScrollPane(list));

frame.setSize(300, 200);
frame.setVisible(true);
}
}</source>



== Rendering JList Elements ==

<OL><LI>Every JList has an installed cell renderer that draws every cell.</LI><LI>A class that implements the ListCellRenderer interface provides this renderer.</LI><LI>When it"s time to draw each cell, the interface"s sole method is called.</LI><LI>The JList has an installed renderer.</LI><LI>The returned renderer provides the specific rendering for that one cell of the JList.</LI><LI>The JList uses the rendering to draw the element, and then gets the next renderer.</LI></OL>



<source lang="java">
public interface ListCellRenderer {
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus);
}</source>



== Set the item dimensions using a sample value ==



<source lang="java">
import javax.swing.JList;
public class Main {
public static void main(String[] argv) throws Exception {
String[] items = { "A", "B", "C", "D" };
JList list = new JList(items);
String protoCellValue = "My Sample Item Value";
list.setPrototypeCellValue(protoCellValue);
}
}</source>



== Setting the Dimensions of an Item in a JList Component ==



<source lang="java">
import javax.swing.JList;
public class Main {
public static void main(String[] argv) throws Exception {
String[] items = { "A", "B", "C", "D" };
JList list = new JList(items);
// Set the item width
int cellWidth = 200;
list.setFixedCellWidth(cellWidth);
// Set the item height
int cellHeight = 18;
list.setFixedCellHeight(cellHeight);
}
}</source>



== The items can be arbitrary objects. The toString() method of the objects is displayed in the list component. ==



<source lang="java">
import javax.swing.JList;
public class Main {
public static void main(String[] argv) throws Exception {
Object[] items2 = { new Integer(123), new java.util.Date() };
JList list = new JList(items2);

}
}</source>

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в 17:44, 31 мая 2010

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