有没有办法根据它们在 JPanel 中显示的顺序（从左上到右下）而不是它们添加到 JPanel 的顺序来获取 JPanel 中的组件列表？
这似乎按照它们添加到面板的顺序获取组件
Component[] comps = myJPanel.getComponents();
问问题
1967 次
2 回答
4
看一下Container#getFocusTraversalPolicy，它返回一个FocusTraversalPolicy具有通过容器确定焦点移动的方法。
这（应该）为您提供组件的自然顺序（从布局管理器和焦点管理器的角度来看）
我会从FocusTraversalPolicy#getFirstComponent(Container)和开始FocusTraversalPolicy#getComponentAfter(Container, Component)
如果这不起作用，您可能需要为自己编写一个自定义Comparator并相应地对组件数组进行排序
更新 - 焦点遍历示例
public class ComponentOrder {
public static void main(String[] args) {
new ComponentOrder();
}
public ComponentOrder() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
BodyPane body = new BodyPane();
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(body);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
Container focusRoot = body.getFocusCycleRootAncestor();
FocusTraversalPolicy ftp = focusRoot.getFocusTraversalPolicy();
Component comp = ftp.getFirstComponent(body);
Component first = comp;
while (comp != null) {
System.out.println(" - " + comp);
comp = ftp.getComponentAfter(focusRoot, comp);
if (comp.equals(first)) {
break;
}
}
}
});
}
public class BodyPane extends JPanel {
private JTextField fldFirstName;
private JTextField fldMiddleName;
private JTextField fldLastName;
private JTextField fldDateOfBirth;
private JTextField fldEMail;
private JButton okButton;
private JButton cancelButton;
public BodyPane() {
setLayout(new BorderLayout());
add(createFieldsPane());
add(createButtonsPane(), BorderLayout.SOUTH);
}
public JPanel createButtonsPane() {
JPanel panel = new JPanel(new FlowLayout());
panel.add((okButton = createButton("Ok")));
panel.add((cancelButton = createButton("Cancel")));
return panel;
}
protected JButton createButton(String text) {
return new JButton(text);
}
public JPanel createFieldsPane() {
JPanel panel = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.insets = new Insets(2, 2, 2, 2);
gbc.gridx = 0;
gbc.gridy = 0;
gbc.anchor = GridBagConstraints.WEST;
panel.add(createLabel("First Name:"), gbc);
gbc.gridy++;
panel.add(createLabel("Middle Name:"), gbc);
gbc.gridy++;
panel.add(createLabel("Last Name:"), gbc);
gbc.gridy++;
panel.add(createLabel("Date of Birth:"), gbc);
gbc.gridy++;
panel.add(createLabel("EMail:"), gbc);
gbc.gridy = 0;
gbc.gridx++;
gbc.weightx = 1;
panel.add((fldFirstName = createField()), gbc);
gbc.gridy++;
panel.add((fldLastName = createField()), gbc);
gbc.gridy++;
panel.add((fldMiddleName = createField()), gbc);
gbc.gridy++;
panel.add((fldDateOfBirth = createField()), gbc);
gbc.gridy++;
panel.add((fldEMail = createField()), gbc);
JPanel filler = new JPanel();
filler.setOpaque(false);
gbc.gridy++;
gbc.weightx = 1;
gbc.weighty = 1;
panel.add(filler, gbc);
return panel;
}
protected JLabel createLabel(String text) {
return new JLabel(text);
}
protected JTextField createField() {
JTextField field = new JTextField(12);
return field;
}
}
}
比较器示例
以下示例使用比较器来确定组件的流向。此版本将父容器中的所有组件转换为该容器坐标空间，因此应该可以将其与复合容器一起使用。
nb我偷了javax.swing.LayoutComparator受包保护的比较器（这对 SwingTeam 来说很好）并修改它以将组件坐标转换回父坐标空间
public class ComponentOrder {
public static void main(String[] args) {
new ComponentOrder();
}
public ComponentOrder() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
BodyPane body = new BodyPane();
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(body);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
List<Component> components = new ArrayList<Component>(25);
getContents(body, components);
LayoutComparator lc = new LayoutComparator(body);
lc.setComponentOrientation(body.getComponentOrientation());
Collections.sort(components, lc);
for (Component comp : components) {
System.out.println(comp);
}
}
});
}
protected void getContents(Container container, List<Component> components) {
for (Component comp : container.getComponents()) {
components.add(comp);
if (comp instanceof Container) {
getContents((Container) comp, components);
}
}
}
public class BodyPane extends JPanel {
private JTextField fldFirstName;
private JTextField fldMiddleName;
private JTextField fldLastName;
private JTextField fldDateOfBirth;
private JTextField fldEMail;
private JButton okButton;
private JButton cancelButton;
public BodyPane() {
setLayout(new BorderLayout());
add(createFieldsPane());
add(createButtonsPane(), BorderLayout.SOUTH);
}
public JPanel createButtonsPane() {
JPanel panel = new JPanel(new FlowLayout());
panel.add((okButton = createButton("Ok")));
panel.add((cancelButton = createButton("Cancel")));
return panel;
}
protected JButton createButton(String text) {
return new JButton(text);
}
public JPanel createFieldsPane() {
JPanel panel = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.insets = new Insets(2, 2, 2, 2);
gbc.gridx = 0;
gbc.gridy = 0;
gbc.anchor = GridBagConstraints.WEST;
panel.add(createLabel("First Name:"), gbc);
gbc.gridy++;
panel.add(createLabel("Middle Name:"), gbc);
gbc.gridy++;
panel.add(createLabel("Last Name:"), gbc);
gbc.gridy++;
panel.add(createLabel("Date of Birth:"), gbc);
gbc.gridy++;
panel.add(createLabel("EMail:"), gbc);
gbc.gridy = 0;
gbc.gridx++;
gbc.weightx = 1;
panel.add((fldFirstName = createField("FirstName")), gbc);
gbc.gridy++;
panel.add((fldLastName = createField("LastName")), gbc);
gbc.gridy++;
panel.add((fldMiddleName = createField("MiddleName")), gbc);
gbc.gridy++;
panel.add((fldDateOfBirth = createField("DateOfBirth")), gbc);
gbc.gridy++;
panel.add((fldEMail = createField("EMail")), gbc);
JPanel filler = new JPanel();
filler.setOpaque(false);
gbc.gridy++;
gbc.weightx = 1;
gbc.weighty = 1;
panel.add(filler, gbc);
return panel;
}
protected JLabel createLabel(String text) {
JLabel label = new JLabel(text);
label.setName(text);
return label;
}
protected JTextField createField(String name) {
JTextField field = new JTextField(12);
field.setName("Field-" + name);
return field;
}
}
public class LayoutComparator implements Comparator<Component>, java.io.Serializable {
private static final int ROW_TOLERANCE = 10;
private boolean horizontal = true;
private boolean leftToRight = true;
private Component parent;
public LayoutComparator(Component parent) {
this.parent = parent;
}
void setComponentOrientation(ComponentOrientation orientation) {
horizontal = orientation.isHorizontal();
leftToRight = orientation.isLeftToRight();
}
public int compare(Component a, Component b) {
if (a == b) {
return 0;
}
// Row/Column algorithm only applies to siblings. If 'a' and 'b'
// aren't siblings, then we need to find their most inferior
// ancestors which share a parent. Compute the ancestory lists for
// each Component and then search from the Window down until the
// hierarchy branches.
if (a.getParent() != b.getParent()) {
LinkedList<Component> aAncestory = new LinkedList<Component>();
for (; a != null; a = a.getParent()) {
aAncestory.add(a);
if (a instanceof Window) {
break;
}
}
if (a == null) {
// 'a' is not part of a Window hierarchy. Can't cope.
throw new ClassCastException();
}
LinkedList<Component> bAncestory = new LinkedList<Component>();
for (; b != null; b = b.getParent()) {
bAncestory.add(b);
if (b instanceof Window) {
break;
}
}
if (b == null) {
// 'b' is not part of a Window hierarchy. Can't cope.
throw new ClassCastException();
}
for (ListIterator<Component> aIter = aAncestory.listIterator(aAncestory.size()),
bIter = bAncestory.listIterator(bAncestory.size());;) {
if (aIter.hasPrevious()) {
a = aIter.previous();
} else {
// a is an ancestor of b
return -1;
}
if (bIter.hasPrevious()) {
b = bIter.previous();
} else {
// b is an ancestor of a
return 1;
}
if (a != b) {
break;
}
}
}
Point pa = SwingUtilities.convertPoint(a, a.getLocation(), parent);
Point pb = SwingUtilities.convertPoint(b, b.getLocation(), parent);
int ax = pa.x, ay = pa.y, bx = pb.x, by = pb.y;
int zOrder = a.getParent().getComponentZOrder(a) - b.getParent().getComponentZOrder(b);
if (horizontal) {
if (leftToRight) {
// LT - Western Europe (optional for Japanese, Chinese, Korean)
if (Math.abs(ay - by) < ROW_TOLERANCE) {
return (ax < bx) ? -1 : ((ax > bx) ? 1 : zOrder);
} else {
return (ay < by) ? -1 : 1;
}
} else { // !leftToRight
// RT - Middle East (Arabic, Hebrew)
if (Math.abs(ay - by) < ROW_TOLERANCE) {
return (ax > bx) ? -1 : ((ax < bx) ? 1 : zOrder);
} else {
return (ay < by) ? -1 : 1;
}
}
} else { // !horizontal
if (leftToRight) {
// TL - Mongolian
if (Math.abs(ax - bx) < ROW_TOLERANCE) {
return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
} else {
return (ax < bx) ? -1 : 1;
}
} else { // !leftToRight
// TR - Japanese, Chinese, Korean
if (Math.abs(ax - bx) < ROW_TOLERANCE) {
return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
} else {
return (ax > bx) ? -1 : 1;
}
}
}
}
}
}
于 2012-12-02T22:28:50.930 回答
0
虽然之前提交的解决方案很巧妙，但（总体上）满足我大部分要求的方法相当简单，并且依赖于窗口架构的左上角有零零（根）点。
由于确切的编码将取决于您选择使用哪些库，让我试探性地描述随后的过程：
任意一点到原点的距离(x,y)为(x^2 + y^2)**(0.5)。使用这个可以构造一个影子阵列，它用一个数字来镜像每一对。通过简单地对这些距离中的每一个进行关系升序排序，可以得出从左上到右下顺序的相当好的近似值。
有一些病态的例子应该避免（或至少理解）。例如，使用指向屏幕左上角的指南针将生成无限数量的点，这些点与原点的距离完全相同。
为了解决这个问题，可以简单地用一个乘数对x或y值进行预缩放，然后再对其进行平方并将其与所描述的另一个平方单位相结合。这将按比例"y"为高于x窗口左边缘的 a 提供更多价值，反之亦然。
于 2013-04-13T21:59:53.797 回答