在尝试从 Main 运行我的基本 GUI 应用程序时，我以某种方式设法首先显示 GUI（但它小于我在代码中设置的大小并且不显示任何组件）然后神奇地（在添加 pack()和 setlocationrelativeto(null)) 它根本不会弹出。我正在使用 Netbeans（如果有帮助的话），在 Main 它给了我一个工具提示，我的 GUI“从未使用过”，因此它运行并输出“已完成的构建”，而不是继续运行并显示 GUI。我提供了 2 组代码（1）主要方法和（2）GUI 类。请让我知道我是否感到困惑，因为这在我的脑海中当然是有道理的，但可能沟通不畅。我没有包含完整的代码，但如果有必要，请告诉我，我会这样做。
package logTime;
public class LogInTime {
public static void main(String[] args) {
try{
LogAppFrame app = new LogAppFrame(); //IDE gives tooltip that app is unused
}
catch(Exception e){
System.err.println("\n\nError Occurred: "); //am going to print message later
}
}
}
实际的 GUI 代码 - 不包括导入或动作监听器：
public void LogAppFrame(){
frame = new JFrame("Time Log Application");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
cl = new CardLayout();
frame.getContentPane().setLayout(cl);
//frame.setLayout(cl);
frame.setSize(new Dimension(375,385));
logNewFrame = new JPanel();
logNewFrame.setLayout(new GridLayout(5,1));
logNewFrame.setBorder(new EmptyBorder(20,20,20,20));
frame.getContentPane().add(logNewFrame, "logNewFrame");
historyFrame = new JPanel();
historyFrame.setLayout(new GridLayout(2,1)); //given 0 for rows to add numerous rows
historyFrame.setBorder(new EmptyBorder(20,20,20,20));
frame.getContentPane().add(historyFrame, "historyFrame");
.
.
.
//added lots of components but will not include code as there is no error within this portion of code - i used to have both Main and LogAppFrame class all together and my GUI worked and showed components but I felt it may be best practice not to do it this way and cardlayout wasnt working
.
.
.
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
在下面添加 SSCE：
package logTime;
import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.event.*;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class LogAppFrame{
private static JFrame frame;
private static CardLayout cl;
//menu option components
/**
* Help option: How To Use/Read Me - explains how to use it 8 Hour Day -
* shows the arrival and leave time based on lunch type
*/
/**
* Log New Date option: shows screen to input new values into date
*/
/**
* View Past Dates option: shows all past dates since forever - may add
* month tabs later
*/
/**
* Edit Past Date option: doesnt exist yet but will be added to View Past
* menu option as side button to edit any old date
*/
private static JMenuBar menuBar = new JMenuBar();
private static JMenu help;
private static JMenuItem logNewDate;
private static JMenuItem viewPastDates;
private static JMenuItem workDay;
private static JMenuItem about;
//Log New Date components
/**
* 4 labels, 1 button, 1 calendar, 2 dropdowns, 2 textfields, 5x2 gridlayout
*/
private static JLabel dateToday;
private static JLabel timeInToday;
private static JLabel timeOutToday;
private static JLabel lunchTypeToday;
private static JLabel timeColon1;
private static JLabel timeColon2;
private static JButton saveButton;
private static JComboBox month;
private static JComboBox day;
private static JComboBox year;
private static JComboBox amPm1;
private static JComboBox amPm2;
private static JComboBox hrTimeIn;
private static JComboBox hrTimeOut;
private static JComboBox minTimeIn;
private static JComboBox minTimeOut;
private static JPanel dateTodayPanel;
private static JPanel timeInPanel;
private static JPanel timeOutPanel;
private static JPanel lunchTypePanel;
private static JPanel saveButtonPanel;
private static JComboBox lunchType;
//View Past Dates components
/**
* 4x*infinitiy* gridlayout or have a flowlayout, 4 labels
*/
private static JLabel pastDates;
private static JLabel pastTimeIns;
private static JLabel pastTimeOuts;
private static JLabel pastLunchTypes;
private static JPanel headers; //holds header labels
private static JPanel oldLogs; //will hold all past log panels
//Frames to hold the logNew and viewOld views
private static JPanel logNewFrame;
private static JPanel historyFrame;
public void LogAppFrame(){
frame = new JFrame("Time Log Application");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
cl = new CardLayout();
frame.getContentPane().setLayout(cl);
//frame.setLayout(cl);
frame.setSize(new Dimension(375,385));
logNewFrame = new JPanel();
logNewFrame.setLayout(new GridLayout(5,1));
logNewFrame.setBorder(new EmptyBorder(20,20,20,20));
frame.getContentPane().add(logNewFrame, "logNewFrame");
historyFrame = new JPanel();
historyFrame.setLayout(new GridLayout(2,1)); //given 0 for rows to add numerous rows
historyFrame.setBorder(new EmptyBorder(20,20,20,20));
frame.getContentPane().add(historyFrame, "historyFrame");
//Menu components
menuBar = new JMenuBar();
help = new JMenu("Help");
logNewDate = new JMenuItem("Log New Date");
viewPastDates = new JMenuItem("View Past Dates");
workDay = new JMenuItem("8 Hour Day");
about = new JMenuItem("How To ...");
help.add(workDay);
help.add(about);
menuBar.add(logNewDate);
menuBar.add(viewPastDates);
menuBar.add(help);
frame.setJMenuBar(menuBar);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}