我把一些JPanel放到另一个JPanel中,它的布局是Box Layout和Y-Axis.
在我放置所有面板后,我需要从JPanel容器面板中获取每个添加的JPanel的Y位置.但是,当我试图得到它时,每个JPanel的Y位置总是为零.请告诉我如何从JPanel容器JPanel获取每个Jpanel的Y位置.
在我放置所有面板后,我需要从JPanel容器面板中获取每个添加的JPanel的Y位置.但是,当我试图得到它时,每个JPanel的Y位置总是为零.请告诉我如何从JPanel容器JPanel获取每个Jpanel的Y位置.
这就是我所做的,
JPanel panelHolder = new JPanel(new BoxLayout(this,BoxLayout.Y_AXIS));
for(int i = 0; i< 10; i++){
JPanel p = new JPanel();
panelHolder.add(p);
}
int componentCount = panelHolder.getComponentCount();
for (int j = 0; i < componentCount ; j++) {
Component c = pnlRowHolder.getComponent(i);
JPanel p = (JPanel)c;
System.out.println(p.getY());//I get zero for all
}
解决方法
将你的JPanel添加到JFrames contentPane,这样你就可以使用getX()和get()获得X和Y坐标,虽然我建议先添加所有组件,因为这些点可能随着更多组件的添加而变化,然后变为trashgod说只需在框架实例上调用pack().
我做了一个简短的样本来证明：
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test {
public static void main(String[] args) {
SwingUtilities.invokelater(new Runnable() {
@Override
public void run() {
new test().createAndShowUI();
}
});
}
private void createAndShowUI() {
JFrame frame = new JFrame("Test");
frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
initComponents(frame);
frame.pack();//call pack
printPanelCompPoints(mainPanel);//produces correct coords
frame.setVisible(true);
}
private JPanel mainPanel;
private void initComponents(JFrame frame) {
mainPanel = new JPanel(new BorderLayout());
JPanel centerPanel = new JPanel();
JPanel northPanel = new JPanel();
JPanel southPanel = new JPanel();
JPanel westPanel = new JPanel();
JPanel eastPanel = new JPanel();
centerPanel.add(new JLabel("CENTER"));
northPanel.add(new JLabel("norTH"));
eastPanel.add(new JLabel("EAST"));
southPanel.add(new JLabel("SOUTH"));
westPanel.add(new JLabel("WEST"));
mainPanel.add(centerPanel,BorderLayout.CENTER);
mainPanel.add(northPanel,BorderLayout.norTH);
mainPanel.add(southPanel,BorderLayout.soUTH);
mainPanel.add(eastPanel,BorderLayout.EAST);
mainPanel.add(westPanel,BorderLayout.WEST);
frame.getContentPane().add(mainPanel);
printPanelCompPoints(mainPanel);//produces all 0's
}
private void printPanelCompPoints(JPanel mainPanel) {
for (int i = 0; i < mainPanel.getComponentCount(); i++) {
System.out.println(mainPanel.getComponent(i).getX() + "," + mainPanel.getComponent(i).getY());
}
}
}
正如你所看到的,调用printPanelCompPoints(mainPanel);在initComponents(JFrame框架)中产生全0,(因为它们已添加到框架中,但尚未调用`pack()).
0,0
0,0
但是在调用printPanelCompPoints(mainPanel)的JFrames实例上调用pack()之后的createAndShowUI()中;产生正确的共同作用：
44,26
0,52
99,26