我正在开发一个应用程序，该应用程序查询数据库并将该信息提取到我已添加到 JFrame 的几个 JPanel 上。每隔 30 秒，我在 JFrame 中将其中一个的可见性设置为 false，将另一个的可见性设置为 true，以交替显示其中一个。
该应用程序在 Windows 中运行良好，但是当我将其放在我的 Ubuntu 计算机上(运行 XFCE 和 openjdk-7-jre)时，面板不显示。 JFrame 中的其他组件确实出现了，但我不确定出了什么问题。同样，该程序在 Windows 中运行正确，但在 Ubuntu 中运行不正确。
我试图将我的代码精简为可以自行编译和运行的代码，但我知道我的代码一团糟。我几乎没有做过 Java 编程，所以我很抱歉这一切将变得多么丑陋!我还删除了数据库内容，因为它正在工作，因此你们都不需要看到。
感谢任何能给我指明正确方向的人!
package productivityDisplay;
import java.awt.Color;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Display implements ActionListener {
// Sizing constants
public boolean trimNames = false; // if true, trims to 10 characters (use
// this if something is cut off)
int refreshRate = 600000; // Refresh rate for Data (milliseconds)
int margin = 2;
int labelHeight = 76;
Font defaultFont = new Font("Tahoma", Font.PLAIN, 50);
Color DodgerBlue = new Color(30, 144, 255);
Color OrangeRed = new Color(255, 69, 0);
Color DarkGreen = new Color(0, 100, 0);
// End Sizing constants
// Controls
private JLabel lblCountDown;
public int countDown;
private Timer refresh;
private JFrame frame;
private JLabel lblCurrTime;
private JPanel pnlGrind1, pnlGrind2;
private JLabel lblWeekSummary, lblRepairCredit,
lblRepair2Count, lblCustom1, lblCustom2,
lblQC, lblRepair, lblRepair2;
@SuppressWarnings("rawtypes")
private JComboBox cmbTeamNames;
// End Controls
// Data Variables
private int currentTeam;
// End Data Variables
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
try {
Display window = new Display(1); // Attempts to show
// the
// window
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
throw new Error("Yeah, it's broken.");
}
}
});
}
public Display(int team) {
initialize();
cmbTeamNames.setSelectedIndex(team);
getData();
}
/**
* @wbp.parser.entryPoint
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
private void initialize() {
frame = new JFrame();
frame.setVisible(true);
frame.setExtendedState(frame.getExtendedState() | JFrame.MAXIMIZED_BOTH); // Maximize
// Window
int width = frame.getWidth();
int height = frame.getHeight();
//frame.setResizable(true); // Can't be resized
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setLayout(null);
// MASSIVE CHUNK OF LAYOUT CODE //
String[] strTeamNames = { "", "Grinding", "Finishing" };
cmbTeamNames = new JComboBox(strTeamNames); // Combo Box (Grinding,
// finishing)
cmbTeamNames.setFont(new Font("Tahoma", Font.PLAIN, 40));
cmbTeamNames.setBounds(20, 11, 297, 67);
frame.getContentPane().add(cmbTeamNames);
cmbTeamNames.setName("cmbTeamNames");
cmbTeamNames.addActionListener(this);
lblCurrTime = new JLabel("Clock");
lblCurrTime.setFont(new Font("Tahoma", Font.PLAIN, 99));
lblCurrTime.setBounds((width - 350), 11, 300, 100);
frame.getContentPane().add(lblCurrTime);
countDown = 0;
lblCountDown = new JLabel("Next update in: "+countDown);
lblCountDown.setFont(new Font("Tahoma", Font.PLAIN, 40));
lblCountDown.setBounds(cmbTeamNames.getX() + cmbTeamNames.getWidth()
+ 40, 20, 400, 50);
frame.getContentPane().add(lblCountDown);
// Grinding Layout 2
pnlGrind2 = new JPanel();
pnlGrind2.setBounds(20, 89, (width - 50), height - 130);
frame.getContentPane().add(pnlGrind2);
pnlGrind2.setLayout(null);
pnlGrind2.setBorder(BorderFactory.createLineBorder (Color.blue, 2));
// Column1
JSeparator separator = new JSeparator();
separator.setBounds(0, (labelHeight + margin - 1), 300, 10);
pnlGrind2.add(separator);
// End Column1
// Column2
int leftSet = 450;
JSeparator separator2 = new JSeparator();
separator2.setBounds(leftSet, (labelHeight + margin - 1), 200, 10);
pnlGrind2.add(separator2);
// End Column2
// Column3
leftSet = 750;
JSeparator separator3 = new JSeparator();
separator3.setBounds(leftSet, (labelHeight + margin - 1), 200, 10);
pnlGrind2.add(separator3);
// End Column3
// Bottom rows
lblRepair2 = new JLabel("Repair Credit:");
pnlGrind2.add(lblRepair2);
lblRepair2.setFont(defaultFont);
lblRepair2.setForeground(DodgerBlue);
lblRepair2Count = new JLabel("");
lblRepair2Count.setBounds(lblRepair2.getX() + lblRepair2.getWidth()
+ margin, lblRepair2.getY(), 515, labelHeight);
pnlGrind2.add(lblRepair2Count);
lblRepair2Count.setFont(defaultFont);
lblRepair2Count.setForeground(DodgerBlue);
// End Bottom rows
pnlGrind2.setVisible(false);
pnlGrind2.setBackground(new Color(0, 0, 204)); // Used to see panel
// better
// End Grinding Layout 2
// Grinding Layout 1
pnlGrind1 = new JPanel();
pnlGrind1.setBounds(20, 89, (width - 50), height - 130);
frame.getContentPane().add(pnlGrind1);
pnlGrind1.setLayout(null);
pnlGrind1.setBorder(BorderFactory.createLineBorder (Color.blue, 2));
pnlGrind1.setVisible(false);
pnlGrind1.setBackground(new Color(255, 0, 204)); // Used to see panel
// better
// Left Side
lblWeekSummary = new JLabel("Week Summary (Measured at Buffing)");
lblWeekSummary.setBounds(0, 0, 515, 37);
pnlGrind1.add(lblWeekSummary);
lblWeekSummary.setFont(new Font("Tahoma", Font.PLAIN, 30));
// Spacing
lblCustom1 = new JLabel("Custom:");
lblCustom1.setBounds(0,
lblWeekSummary.getY() + (lblWeekSummary.getHeight() + margin)
* 2, 515, labelHeight);
pnlGrind1.add(lblCustom1);
lblCustom1.setFont(defaultFont);
lblCustom1.setForeground(OrangeRed);
lblRepairCredit = new JLabel("Repair Credit:");
lblRepairCredit.setBounds(0,
lblCustom1.getY() + (lblCustom1.getHeight() + margin), 515,
labelHeight);
pnlGrind1.add(lblRepairCredit);
lblRepairCredit.setFont(defaultFont);
lblRepairCredit.setForeground(DodgerBlue);
// Spacing
lblQC = new JLabel("QC");
lblQC.setBounds(
0,
(int) (lblRepairCredit.getY() + (lblRepairCredit.getHeight() + margin) * 1.5),
515, labelHeight);
pnlGrind1.add(lblQC);
lblQC.setFont(defaultFont);
lblQC.setForeground(DarkGreen);
lblCustom2 = new JLabel("Custom:");
lblCustom2.setBounds(0, lblQC.getY() + (lblQC.getHeight() + margin),
515, labelHeight);
pnlGrind1.add(lblCustom2);
lblCustom2.setFont(defaultFont);
lblCustom2.setForeground(DarkGreen);
lblRepair = new JLabel("Repair:");
lblRepair.setBounds(0, lblCustom2.getY()
+ (lblCustom2.getHeight() + margin), 515, labelHeight);
pnlGrind1.add(lblRepair);
lblRepair.setFont(defaultFont);
lblRepair.setForeground(DarkGreen);
// End Left Side
// Right Side
// End Right Side
// End Grinding Layout 1
// END MASSIVE CHUNK OF LAYOUT CODE //
frame.pack();
frame.setExtendedState(frame.getExtendedState() | JFrame.MAXIMIZED_BOTH); // Maximize
// Window
}
// Thread classes
public void getData() {
ActionListener updateData = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
pnlGrind1.repaint();
pnlGrind2.repaint();
countDown = 15;
}
};
refresh = new Timer(refreshRate, updateData);
refresh.start();
}
// End Thread Classes
public void actionPerformed(ActionEvent e) { // Combo box to select team was
// clicked
int team;
team = cmbTeamNames.getSelectedIndex();
currentTeam = team;
countDown=600;
int t2Interval = 5000;
if (team == 1) { // Grinding team
pnlGrind1.setVisible(true);
}
ActionListener alternatePnl = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
// updateData();
alternatePanel(cmbTeamNames.getSelectedIndex());
}
};
new Timer(t2Interval, alternatePnl).start();
}
void alternatePanel(int team) {
if (team == 1) { // If Grinding team
if (pnlGrind1.isVisible()) {
pnlGrind1.setVisible(false);
pnlGrind2.setVisible(true);
} else {
pnlGrind2.setVisible(false);
pnlGrind1.setVisible(true);
}
}
}
}
最佳答案
因为 JPanel 获得负高度和宽度:
pnlGrind2.setBounds(20, 89, (width - 50), height - 130);
，并且宽度=高度=0。您刚刚初始化了 JFrame，因此默认情况下均为 0，您可以立即将这些值分配给 height 和 width。
如果已经进行绝对布局，请保持一致并尽快指定框架大小:
private void initialize() {
frame = new JFrame();
frame.setSize(800, 600);
...
之后 JPanels 出现在我的 Ubuntu 机器的屏幕上。
关于Java JPanel 不会出现在 Linux 中的 JFrame 中，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14282296/