Question

我知道在这个问题上已经有很多主题，但我保证你已经用尽了搜索。

在我的应用程序开始时，＆＃34; ExampleGUI＆＃34;窗口应该显示，当单击日历按钮时，弹出日历框架，用户选择一个日期，表示为字符串。此字符串以及一些其他信息将作为新的ExampleGUI传递回ExampleGUI。然后它将转到方法updateDate，它应该显示用户在当前帧上选择的日期，作为JLabel。但是，无论我尝试什么，JLabel都不会显示或不会更新。我知道有关SetText的信息，它目前还没有包含在我的代码中，但是我已经尝试了它并且它不起作用。我知道它正确传递日期，因为System.out.println可以正常工作。如果你有任何帮助，我将永远感激我正式难倒。

更新添加了我可以做的最简单的代码 - 对不起，日历太长了，我无法承担太多，但我保证这不是你需要它来运行问题所在的GUI的问题。

谢谢！

CODE：

亚军类：

import java.awt.EventQueue;

public class Runner {

    public Runner() {

    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                GUI frame = new GUI();
                frame.setVisible(true);

            }
        });
    }
}

GUI类：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GUI extends JFrame {

    private JPanel contentPane;

    public String newDate;
    public String myStartEnd;
    public String StartDate;
    public JLabel lblFinalStartDate;
    public JLabel lblFinalEndDate;

    public JPanel panelSearchCriteria = new JPanel();

    public GUI(){
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 800, 600);
        contentPane = new JPanel();
        setContentPane(contentPane);
        GridBagLayout gbl_contentPane = new GridBagLayout();
        contentPane.setLayout(gbl_contentPane);



        GridBagConstraints gbc_panelSearchCriteria = new GridBagConstraints();
        gbc_panelSearchCriteria.gridx = 0;
        gbc_panelSearchCriteria.gridy = 0;
        contentPane.add(panelSearchCriteria, gbc_panelSearchCriteria);
        GridBagLayout gbl_panelSearchCriteria = new GridBagLayout();
        panelSearchCriteria.setLayout(gbl_panelSearchCriteria);

        JButton btnChooseSDate = new JButton("Choose Date");
        btnChooseSDate.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                String source = new String("Start");
                Calndar startCal = new Calndar(source);
            }
        });
        GridBagConstraints gbc_btnChooseSDate = new GridBagConstraints();
        gbc_btnChooseSDate.gridx = 1;
        gbc_btnChooseSDate.gridy = 1;
        panelSearchCriteria.add(btnChooseSDate, gbc_btnChooseSDate);
    }

    public GUI(String str, String soE) {
        this();
        updateDate(str, soE);
    }

    public void updateDate(String d, String se) {
        String tempdate = new String(d + "");
        String answer = new String(se + "");


        if (answer.equals("Start")) {
            StartDate = new String(tempdate + "");
            lblFinalStartDate = new JLabel(StartDate);

            GridBagConstraints gbc_lblFinalStartDate = new GridBagConstraints();
            gbc_lblFinalStartDate.insets = new Insets(0, 0, 0, 5);
            gbc_lblFinalStartDate.gridx = 2;
            gbc_lblFinalStartDate.gridy = 1;
            this.panelSearchCriteria.add(lblFinalStartDate, gbc_lblFinalStartDate);

            System.out.println(lblFinalStartDate.getText());    
        }else{


        }
    }
}

日历类：

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;


public class Calndar extends JFrame {

    private JPanel contentPane;
    private JTable table;
    public int realDay, realMonth, realYear, currentMonth, currentYear;
    public JButton btnPrev = new JButton("<<");
    public JButton btnNext = new JButton(">>");
    public JLabel Monthlabel = new JLabel("");

    public int returnedDAY, returnedMONTH, returnedYEAR;
    public String FinalDate;


    public Calndar(String SoE) {
        setBounds(100, 100, 330, 430);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        GregorianCalendar cal = new GregorianCalendar();
        realDay = cal.get(GregorianCalendar.DAY_OF_MONTH);
        realMonth = cal.get(GregorianCalendar.MONTH);
        realYear = cal.get(GregorianCalendar.YEAR);
        currentMonth = realMonth;
        currentYear = realYear;

        JPanel panel = new JPanel();
        contentPane.add(panel, BorderLayout.CENTER);
        GridBagLayout gbl_panel = new GridBagLayout();
        gbl_panel.columnWidths = new int[] { 0, 0, 0, 0 };
        gbl_panel.rowHeights = new int[] { 0, 0, 0, 0 };
        gbl_panel.columnWeights = new double[] { 0.0, 1.0, 0.0, Double.MIN_VALUE };
        gbl_panel.rowWeights = new double[] { 0.0, 1.0, 0.0, Double.MIN_VALUE };
        panel.setLayout(gbl_panel);



        GridBagConstraints gbc_label = new GridBagConstraints();
        gbc_label.insets = new Insets(0, 0, 5, 5);
        gbc_label.gridx = 1;
        gbc_label.gridy = 0;
        panel.add(Monthlabel, gbc_label);



        JScrollPane scrollPane = new JScrollPane();
        GridBagConstraints gbc_scrollPane = new GridBagConstraints();
        gbc_scrollPane.gridwidth = 3;
        gbc_scrollPane.insets = new Insets(0, 0, 5, 0);
        gbc_scrollPane.fill = GridBagConstraints.BOTH;
        gbc_scrollPane.gridx = 0;
        gbc_scrollPane.gridy = 1;
        panel.add(scrollPane, gbc_scrollPane);

        table = new JTable();
        table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        table.setRowHeight(35);
        table.setCellSelectionEnabled(true);
        table.setModel(new DefaultTableModel(
                new Object[][] { { null, null, null, null, null, null, null },
                        { null, null, null, null, null, null, null }, { null, null, null, null, null, null, null },
                        { null, null, null, null, null, null, null }, { null, null, null, null, null, null, null },
                        { null, null, null, null, null, null, null }, },
                new String[] { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }));
        scrollPane.setViewportView(table);


        JPanel panel_1 = new JPanel();
        contentPane.add(panel_1, BorderLayout.SOUTH);

        JButton btnChoose = new JButton("Select");
        btnChoose.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int row = table.getSelectedRow();
                int col = table.getSelectedColumn();

                if (row == (-1) || col == (-1)) {
                    JOptionPane.showMessageDialog(null, "Please Select a Date", "Error", JOptionPane.WARNING_MESSAGE);
                } else {
                    returnDate(row, col);
                    GUI DS1 = new GUI(getFinalDate(), SoE);
                    dispose();
                }
            }
        });
        btnChoose.setMargin(new Insets(5, 20, 5, 20));
        panel_1.add(btnChoose);
        refreshCalendar(realMonth, realYear);
        setVisible(true);
    }

    public void refreshCalendar(int M, int Y) {
        int nod, som;
        Monthlabel.setText("July");


        GregorianCalendar cal = new GregorianCalendar(Y, M, 1);
        nod = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
        som = cal.get(GregorianCalendar.DAY_OF_WEEK);

        for (int i = 0; i < 6; i++) {
            for (int j = 0; j < 7; j++) {
                table.setValueAt(null, i, j);
            }
        }

        for (int i = 1; i <= nod; i++) {
            int row = new Integer((i + som - 2) / 7);
            int column = ((i + som - 2) % 7);
            table.setValueAt(i, row, column);
        }

    }

    public String returnDate(int r, int c) {
        returnedYEAR = 2015;
        returnedMONTH = 7;
        returnedDAY = (int) table.getValueAt(r, c);

        FinalDate = new String("" + returnedYEAR + "-" + returnedMONTH + "-" + returnedDAY);

        return FinalDate;
    }

    public String getFinalDate(){
        if(FinalDate.equals(null)){
            String str = new String("None");
            return str;
        }else{
            return FinalDate;
        }
    }
}

Answer 1

你的问题在这里：

  btnChoose.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
        int row = table.getSelectedRow();
        int col = table.getSelectedColumn();

        if (row == (-1) || col == (-1)) {
           JOptionPane.showMessageDialog(null, "Please Select a Date",
                 "Error", JOptionPane.WARNING_MESSAGE);
        } else {
           returnDate(row, col);
           GUI DS1 = new GUI(getFinalDate(), SoE);  // *****************
           dispose();
        }
     }
  });

您正在创建一个新 GUI对象，该对象与当前显示的GUI实例完全不同。

建议：

新窗口不应该是JFrame，而应该是模态 JDialog。如果它是一个模态对话框，它将从设置为可见的点冻结调用代码，然后一旦对话框不再可见，该代码将恢复流程。
从原始类（GUI的ActionListener。
没有让Kandar对象在GUI中更改任何内容。而是在其动作侦听器中存储选定日期（如果选择了任何内容），并处理对话框。
然后调用类，这里GUI可以在GUI的select ActionStistener中查询Calndar对象，而不是Calndar对象，但是在Calndar设置为可见之后，通过调用Calndar上的公共getter方法来提取所选日期宾语。
然后，GUI可以使用此信息更新其可视化数据。
在正在运行的GUI中添加或删除组件后调用revalidate并重新绘制。
将来，请尝试仅为您的示例程序使用1个文件。

例如。请注意以下代码中的主要更改已使用// !!注释：

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

import java.awt.*;
import java.awt.event.*;
import java.util.GregorianCalendar;

import javax.swing.*;
import javax.swing.border.EmptyBorder;
import javax.swing.table.DefaultTableModel;

public class GUI extends JFrame {

   private JPanel contentPane;

   public String newDate;
   public String myStartEnd;
   public String StartDate;
   public JLabel lblFinalStartDate;
   public JLabel lblFinalEndDate;

   public JPanel panelSearchCriteria = new JPanel();

   public GUI() {
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setBounds(100, 100, 800, 600);
      contentPane = new JPanel();
      setContentPane(contentPane);
      GridBagLayout gbl_contentPane = new GridBagLayout();
      contentPane.setLayout(gbl_contentPane);

      GridBagConstraints gbc_panelSearchCriteria = new GridBagConstraints();
      gbc_panelSearchCriteria.gridx = 0;
      gbc_panelSearchCriteria.gridy = 0;
      contentPane.add(panelSearchCriteria, gbc_panelSearchCriteria);
      GridBagLayout gbl_panelSearchCriteria = new GridBagLayout();
      panelSearchCriteria.setLayout(gbl_panelSearchCriteria);

      JButton btnChooseSDate = new JButton("Choose Date");
      btnChooseSDate.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent arg0) {
            String source = new String("Start");
            Calndar startCal = new Calndar(GUI.this, source); // !!
            startCal.setVisible(true); // !!
            String finalDate = startCal.getFinalDate();
            updateDate(finalDate, source); // !!
         }
      });
      GridBagConstraints gbc_btnChooseSDate = new GridBagConstraints();
      gbc_btnChooseSDate.gridx = 1;
      gbc_btnChooseSDate.gridy = 1;
      panelSearchCriteria.add(btnChooseSDate, gbc_btnChooseSDate);
   }

   public GUI(String str, String soE) {
      this();
      updateDate(str, soE);
   }

   public void updateDate(String d, String se) {
      String tempdate = new String(d + "");
      String answer = new String(se + "");

      if (answer.equals("Start")) {
         StartDate = new String(tempdate + "");
         lblFinalStartDate = new JLabel(StartDate);

         GridBagConstraints gbc_lblFinalStartDate = new GridBagConstraints();
         gbc_lblFinalStartDate.insets = new Insets(0, 0, 0, 5);
         gbc_lblFinalStartDate.gridx = 2;
         gbc_lblFinalStartDate.gridy = 1;
         this.panelSearchCriteria.add(lblFinalStartDate, gbc_lblFinalStartDate);

         System.out.println(lblFinalStartDate.getText());

         revalidate(); // !!
         repaint(); // !!
      } else {

      }
   }

   public static void main(String[] args) {
      EventQueue.invokeLater(new Runnable() {
         public void run() {
            GUI frame = new GUI();
            frame.setVisible(true);
         }
      });
   }
}

class Calndar extends JDialog {  // !!

   private JPanel contentPane;
   private JTable table;
   public int realDay, realMonth, realYear, currentMonth, currentYear;
   public JButton btnPrev = new JButton("<<");
   public JButton btnNext = new JButton(">>");
   public JLabel Monthlabel = new JLabel("");

   public int returnedDAY, returnedMONTH, returnedYEAR;
   public String FinalDate;

   public Calndar(GUI gui, final String SoE) { // !!
      super(gui, "Calndar Title", ModalityType.APPLICATION_MODAL); // !!
      setBounds(100, 100, 330, 430);
      contentPane = new JPanel();
      contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
      contentPane.setLayout(new BorderLayout(0, 0));
      setContentPane(contentPane);

      GregorianCalendar cal = new GregorianCalendar();
      realDay = cal.get(GregorianCalendar.DAY_OF_MONTH);
      realMonth = cal.get(GregorianCalendar.MONTH);
      realYear = cal.get(GregorianCalendar.YEAR);
      currentMonth = realMonth;
      currentYear = realYear;

      JPanel panel = new JPanel();
      contentPane.add(panel, BorderLayout.CENTER);
      GridBagLayout gbl_panel = new GridBagLayout();
      gbl_panel.columnWidths = new int[] { 0, 0, 0, 0 };
      gbl_panel.rowHeights = new int[] { 0, 0, 0, 0 };
      gbl_panel.columnWeights = new double[] { 0.0, 1.0, 0.0, Double.MIN_VALUE };
      gbl_panel.rowWeights = new double[] { 0.0, 1.0, 0.0, Double.MIN_VALUE };
      panel.setLayout(gbl_panel);

      GridBagConstraints gbc_label = new GridBagConstraints();
      gbc_label.insets = new Insets(0, 0, 5, 5);
      gbc_label.gridx = 1;
      gbc_label.gridy = 0;
      panel.add(Monthlabel, gbc_label);

      JScrollPane scrollPane = new JScrollPane();
      GridBagConstraints gbc_scrollPane = new GridBagConstraints();
      gbc_scrollPane.gridwidth = 3;
      gbc_scrollPane.insets = new Insets(0, 0, 5, 0);
      gbc_scrollPane.fill = GridBagConstraints.BOTH;
      gbc_scrollPane.gridx = 0;
      gbc_scrollPane.gridy = 1;
      panel.add(scrollPane, gbc_scrollPane);

      table = new JTable();
      table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
      table.setRowHeight(35);
      table.setCellSelectionEnabled(true);
      table.setModel(new DefaultTableModel(new Object[][] {
            { null, null, null, null, null, null, null },
            { null, null, null, null, null, null, null },
            { null, null, null, null, null, null, null },
            { null, null, null, null, null, null, null },
            { null, null, null, null, null, null, null },
            { null, null, null, null, null, null, null }, }, new String[] {
            "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }));
      scrollPane.setViewportView(table);

      JPanel panel_1 = new JPanel();
      contentPane.add(panel_1, BorderLayout.SOUTH);

      JButton btnChoose = new JButton("Select");
      btnChoose.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            int row = table.getSelectedRow();
            int col = table.getSelectedColumn();

            if (row == (-1) || col == (-1)) {
               JOptionPane.showMessageDialog(null, "Please Select a Date",
                     "Error", JOptionPane.WARNING_MESSAGE);
            } else {
               returnDate(row, col);
               // !! GUI DS1 = new GUI(getFinalDate(), SoE);
               dispose();
            }
         }
      });
      btnChoose.setMargin(new Insets(5, 20, 5, 20));
      panel_1.add(btnChoose);
      refreshCalendar(realMonth, realYear);
      // setVisible(true);
   }

   public void refreshCalendar(int M, int Y) {
      int nod, som;
      Monthlabel.setText("July");

      GregorianCalendar cal = new GregorianCalendar(Y, M, 1);
      nod = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
      som = cal.get(GregorianCalendar.DAY_OF_WEEK);

      for (int i = 0; i < 6; i++) {
         for (int j = 0; j < 7; j++) {
            table.setValueAt(null, i, j);
         }
      }

      for (int i = 1; i <= nod; i++) {
         int row = new Integer((i + som - 2) / 7);
         int column = ((i + som - 2) % 7);
         table.setValueAt(i, row, column);
      }

   }

   public String returnDate(int r, int c) {
      returnedYEAR = 2015;
      returnedMONTH = 7;
      returnedDAY = (int) table.getValueAt(r, c);

      FinalDate = new String("" + returnedYEAR + "-" + returnedMONTH + "-"
            + returnedDAY);

      return FinalDate;
   }

   public String getFinalDate() {
      if (FinalDate.equals(null)) {
         String str = new String("None");
         return str;
      } else {
         return FinalDate;
      }
   }
}

此外：

在主GUI中添加日期时，我不会添加JLabel。而是我创建一个JLabel字段，最初将其添加到GUI，然后在需要时简单地设置它的文本。

JLabel不会更新/显示。初始化问题？

1 个答案: