【问题标题】:How to call on a textfield variable from a keyevent method?如何从 keyevent 方法调用文本字段变量?
【发布时间】:2016-04-14 01:00:43
【问题描述】:

好的,所以我正在做一个 GUI 程序,但我无法检索用户将输入的信息并从另一个类调用它,以便在那里可以访问它。这是我的 GUI 类的主要部分,它从创建第一个文本字段开始:

/**
*Text genereted by Simple GUI Extension for BlueJ
*/
import javax.swing.UIManager.LookAndFeelInfo;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import javax.swing.border.Border;
import javax.swing.*;


public class GUI_project extends JFrame {

private JMenuBar menuBar;
private JButton button1;
private JLabel label1;
private JLabel label2;
private JLabel label3;
private JLabel label4;
private JTextField textfield1;
private JTextField textfield2;
private JTextField textfield3;
public String SoftName;
public String ReportName;
public String Devices;
public int InDevices;

//Constructor 
public GUI_project(){

    setTitle("Software Calculator");
    setSize(500,400);
    //menu generate method
    generateMenu();
    setJMenuBar(menuBar);

    //pane with null layout
    JPanel contentPane = new JPanel(null);
    contentPane.setPreferredSize(new Dimension(500,400));
    contentPane.setBackground(new Color(51,153,0));


    button1 = new JButton();
    button1.setBounds(180,325,150,35);
    button1.setBackground(new Color(214,217,223));
    button1.setForeground(new Color(0,0,0));
    button1.setEnabled(true);
    button1.setFont(new Font("sansserif",0,12));
    button1.setText("Calculate and Save");
    button1.setVisible(true);
    //Set action for key events
    //Call defined method
    button1.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent evt) {
            startApp(evt);
        }
    });


    label1 = new JLabel();
    label1.setBounds(95,12,300,35);
    label1.setBackground(new Color(214,217,223));
    label1.setForeground(new Color(0,0,0));
    label1.setEnabled(true);
    label1.setFont(new Font("SansSerif",0,20));
    label1.setText("Software Agreement Calcuator");
    label1.setVisible(true);

    label2 = new JLabel();
    label2.setBounds(18,102,150,35);
    label2.setBackground(new Color(214,217,223));
    label2.setForeground(new Color(0,0,0));
    label2.setEnabled(true);
    label2.setFont(new Font("SansSerif",0,16));
    label2.setText("Name of Software:");
    label2.setVisible(true);

    label3 = new JLabel();
    label3.setBounds(15,174,300,35);
    label3.setBackground(new Color(214,217,223));
    label3.setForeground(new Color(0,0,0));
    label3.setEnabled(true);
    label3.setFont(new Font("SansSerif",0,16));
    label3.setText("Number of Devices the Software is on:");
    label3.setVisible(true);

    label4 = new JLabel();
    label4.setBounds(17,244,250,35);
    label4.setBackground(new Color(214,217,223));
    label4.setForeground(new Color(0,0,0));
    label4.setEnabled(true);
    label4.setFont(new Font("SansSerif",0,15));
    label4.setText("Name of Report to Save Under:");
    label4.setVisible(true);

    textfield1 = new JTextField();
    textfield1.setBounds(335,102,90,35);
    textfield1.setBackground(new Color(255,255,255));
    textfield1.setForeground(new Color(0,0,0));
    textfield1.setEnabled(true);
    textfield1.setFont(new Font("sansserif",0,12));
    textfield1.setText("");
    textfield1.setVisible(true);
    //Set action for key events
    //Call defined method
    textfield1.addKeyListener(new KeyAdapter() {
        public void keyTyped(KeyEvent evt) {
            getSoftwareName(evt);
        }
    });


    textfield2 = new JTextField();
    textfield2.setBounds(335,173,90,35);
    textfield2.setBackground(new Color(255,255,255));
    textfield2.setForeground(new Color(0,0,0));
    textfield2.setEnabled(true);
    textfield2.setFont(new Font("sansserif",0,12));
    textfield2.setText("");
    textfield2.setVisible(true);
    //Set action for key events
    //Call defined method
    textfield2.addKeyListener(new KeyAdapter() {
        public void keyTyped(KeyEvent evt) {
            number(evt);
        }
    });


    textfield3 = new JTextField();
    textfield3.setBounds(336,240,90,35);
    textfield3.setBackground(new Color(255,255,255));
    textfield3.setForeground(new Color(0,0,0));
    textfield3.setEnabled(true);
    textfield3.setFont(new Font("sansserif",0,12));
    textfield3.setText("");
    textfield3.setVisible(true);
    //Set action for key events
    //Call defined method
    textfield3.addKeyListener(new KeyAdapter() {
        public void keyTyped(KeyEvent evt) {
            FileName(evt);
        }
    });


    //adding components to contentPane panel
    contentPane.add(button1);
    contentPane.add(label1);
    contentPane.add(label2);
    contentPane.add(label3);
    contentPane.add(label4);
    contentPane.add(textfield1);
    contentPane.add(textfield2);
    contentPane.add(textfield3);

    //adding panel to JFrame and seting of window position and close operation
    getContentPane().add(contentPane);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLocationRelativeTo(null);
    pack();
    setVisible(true);
}

//Method keyPressed for button1
public void startApp (ActionEvent evt) {
        Print.Start();
}

//Method actionPerformed for textfield1
public String getSoftwareName (KeyEvent evt) {
        SoftName = textfield1.getText();
        return SoftName;
}

//Method actionPerformed for textfield2

  public int number (KeyEvent evt) {
        char c=evt.getKeyChar();
        if(!(Character.isDigit(c) || (c==KeyEvent.VK_BACK_SPACE)||c==KeyEvent.VK_DELETE)){
            evt.consume();
  }
        this.Devices= this.textfield2.getText();
        InDevices= Integer.parseInt(Devices);
        return InDevices;
 }
  //Method actionPerformed for textfield3
public String FileName (KeyEvent evt) {
        this.ReportName= this.textfield3.getText();
        return ReportName;
}

//method for generate menu
public void generateMenu(){
    menuBar = new JMenuBar();

    JMenu file = new JMenu("File");

    JMenuItem open = new JMenuItem("Open   ");
    open.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O,Event.CTRL_MASK));

    JMenuItem exit = new JMenuItem("Exit   ");
    exit.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q,Event.CTRL_MASK));


    //Setings action for menu item
    //Call defined method
    open.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent evt) {
            openFile(evt);
        }
    });

    //Setings action for menu item
    //Call defined method
    exit.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent evt) {
            Quit(evt);
        }
    });


    file.add(open);
    file.add(exit);

    menuBar.add(file);
}
//Method for Open from menuFile 
private void openFile (ActionEvent evt) {
        PopUp Pop= new PopUp();
        Pop.Frame();
}

//Method for Exit from menuFile 
private void Quit (ActionEvent evt) {
        System.exit(0);
}




 public static void main(String[] args){
    System.setProperty("swing.defaultlaf", "com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            new GUI_project();
        }
    });
}

}

这是第二课:

public static int software;
public static String name;
public static void Company(){
GUI_project main= new GUI_project();
name=main.getSoftwareName();
if(name.equals("Microsoft")||name.equals("Norton")||name.equals("Oracle")||name.equals("CRM")){
    if(name.equals("Microsoft")){
        Name.software = 1200000;
    }else if(name.equals("Norton")){
        Name.software = 3000000;
    }else if(name.equals("Oracle")){
        Name.software = 1700000;
    }else if(name.equals("CRM")){
        Name.software = 2300000;
    }
  }else{
    System.out.println("Not a company, GOOD BYE!");
    System.exit(0);
}
}

我确信这是一个愚蠢而愚蠢的错误,但任何帮助都会很棒。一旦我能够让这两个类工作,其余的应该以相同的方式工作:)

【问题讨论】:

  • 添加GUI_project类的完整代码。
  • 我刚刚上传了完整的代码

标签: java swing user-interface methods key-events


【解决方案1】:

您可以使用列表界面来改进您的第二个类的代码

List <String> companyList = new ArrayList<String>();

companyList.add("Microsoft");
companyList.add("Norton");
companyList.add("Oracle");
companyList.add("CRM");

int index=companyList.indexOf(name);

switch(index){
    case 0: Name.software = 1200000;break;
    case 1: Name.software = 3000000;break;
    case 2: Name.software = 1700000;break;
    case 3: Name.software = 2300000;break;
    case -1: //-1 Signifies it did not match the company names
}

【讨论】:

  • 这实际上并没有回答他的问题,但这是一个可以改进他的代码的好点
  • 它可以使它更容易,但我不喜欢使用数组,因为代码要复杂得多,并且包含 7 个其他类.. 7 个中只有 3 个将使用 GUI 类来检索它来自它的信息,但现在尝试仅合并上述类会很棒
  • @HusseinOkasha ArrayListArray 不同。 String[] 的主要区别通常必须定义其大小 =new String[8]ArrayList 没有。在许多情况下,ArrayList 可能更有用。如果您曾经与他们合作,请记住一些事情
【解决方案2】:

好的,那么基于此...

GUI_project main= new GUI_project();
name=main.getSoftwareName();

您似乎希望在用户与您的表单交互后获得softwareName

在此,您有三个选择,您可以使用某种Observer PatternGUI_project 将在发生某种操作时向任何感兴趣的方发送某种事件(例如,用户按下“确定” " 按钮)

或者您可以使用modal dialog,它将在对话框可见时停止代码的执行,直到它关闭,此时您可以访问您需要的信息。

或者你应该直接把第二类需要的信息传递给它

第二种方法是更常见的方法和更“线性”的方法,这似乎适合您的代码。

但是,在我们兴奋之前,一些家务......

  • 避免使用null 布局,像素完美的布局是现代用户界面设计中的一种错觉。影响组件单个尺寸的因素太多,您无法控制。 Swing 旨在与核心布局管理器一起使用,丢弃这些将导致无穷无尽的问题和问题,您将花费越来越多的时间来尝试纠正
  • 作为一般规则避免KeyListener,但特别是对于文本组件,它们非常不合适,事实上,在你的情况下,ActionListener 会好得多。请参阅How to Use Text FieldsHow to Write an Action Listeners 了解更多详情
  • 如果您需要在文本输入到字段时提供特殊处理,您应该使用DocumentListener,有关详细信息,请参阅Listening for Changes on a Document。如果您想在现场提供实时验证,那么您应该使用 `DocumentFilter,请参阅 Implementing a Document FilterDocumentFilter Examples 了解更多详情

作为一个概念性的想法...

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Event;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                GUI_project project = new GUI_project();

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setJMenuBar(project.generateMenu());
                frame.add(project);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class GUI_project extends JPanel {

        private JButton button1;
        private JLabel label1;
        private JLabel label2;
        private JLabel label3;
        private JLabel label4;
        private JTextField textfield1;
        private JTextField textfield2;
        private JTextField textfield3;
        public String SoftName;
        public String ReportName;
        public String Devices;
        public int InDevices;

        public GUI_project() {

            generateMenu();

            //pane with null layout
            setBackground(new Color(51, 153, 0));

            button1 = new JButton();
            button1.setBackground(new Color(214, 217, 223));
            button1.setForeground(new Color(0, 0, 0));
            button1.setEnabled(true);
            button1.setFont(new Font("sansserif", 0, 12));
            button1.setText("Calculate and Save");
            button1.setVisible(true);
            //Set action for key events
            //Call defined method
            button1.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent evt) {
                    startApp(evt);
                }
            });

            label1 = new JLabel();
            label1.setBackground(new Color(214, 217, 223));
            label1.setForeground(new Color(0, 0, 0));
            label1.setEnabled(true);
            label1.setFont(new Font("SansSerif", 0, 20));
            label1.setText("Software Agreement Calcuator");
            label1.setVisible(true);

            label2 = new JLabel();
            label2.setBackground(new Color(214, 217, 223));
            label2.setForeground(new Color(0, 0, 0));
            label2.setEnabled(true);
            label2.setFont(new Font("SansSerif", 0, 16));
            label2.setText("Name of Software:");
            label2.setVisible(true);

            label3 = new JLabel();
            label3.setBackground(new Color(214, 217, 223));
            label3.setForeground(new Color(0, 0, 0));
            label3.setEnabled(true);
            label3.setFont(new Font("SansSerif", 0, 16));
            label3.setText("Number of Devices the Software is on:");
            label3.setVisible(true);

            label4 = new JLabel();
            label4.setBackground(new Color(214, 217, 223));
            label4.setForeground(new Color(0, 0, 0));
            label4.setEnabled(true);
            label4.setFont(new Font("SansSerif", 0, 15));
            label4.setText("Name of Report to Save Under:");
            label4.setVisible(true);

            textfield1 = new JTextField(10);
            textfield1.setBackground(new Color(255, 255, 255));
            textfield1.setForeground(new Color(0, 0, 0));
            textfield1.setEnabled(true);
            textfield1.setFont(new Font("sansserif", 0, 12));
            textfield1.setText("");
            textfield1.setVisible(true);

            textfield2 = new JTextField(10);
            textfield2.setBackground(new Color(255, 255, 255));
            textfield2.setForeground(new Color(0, 0, 0));
            textfield2.setEnabled(true);
            textfield2.setFont(new Font("sansserif", 0, 12));
            textfield2.setText("");
            textfield2.setVisible(true);
            //Set action for key events
            //Call defined method

            textfield3 = new JTextField(10);
            textfield3.setBackground(new Color(255, 255, 255));
            textfield3.setForeground(new Color(0, 0, 0));
            textfield3.setEnabled(true);
            textfield3.setFont(new Font("sansserif", 0, 12));
            textfield3.setText("");
            textfield3.setVisible(true);
            //Set action for key events
            //Call defined method

            //adding components to contentPane panel
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            gbc.gridx = 0;
            gbc.gridy = 0;
            add(label1, gbc);
            gbc.anchor = GridBagConstraints.EAST;
            gbc.gridy++;
            gbc.gridwidth = 1;
            add(label2, gbc);
            gbc.gridy++;
            add(label3, gbc);
            gbc.gridy++;
            add(label4, gbc);

            gbc.anchor = GridBagConstraints.WEST;
            gbc.gridy = 1;
            gbc.gridx++;
            add(textfield1, gbc);
            gbc.gridy++;
            add(textfield2, gbc);
            gbc.gridy++;
            add(textfield3, gbc);
            gbc.gridy++;

            gbc.gridx = 0;
            gbc.anchor = gbc.EAST;
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            add(button1, gbc);

        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(500, 400);
        }

        public JMenuBar generateMenu() {
            JMenuBar menuBar = new JMenuBar();

            JMenu file = new JMenu("File");

            JMenuItem open = new JMenuItem("Open   ");
            open.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, Event.CTRL_MASK));

            JMenuItem exit = new JMenuItem("Exit   ");
            exit.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, Event.CTRL_MASK));

            //Setings action for menu item
            //Call defined method
            open.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent evt) {
                    openFile(evt);
                }
            });

            //Setings action for menu item
            //Call defined method
            exit.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent evt) {
                    Quit(evt);
                }
            });

            file.add(open);
            file.add(exit);

            menuBar.add(file);

            return menuBar;
        }

        public void startApp(ActionEvent evt) {
            Popup pop = new Popup(textfield1.getText());
            // And what ever you need to do
        }

        private void openFile(ActionEvent evt) {
        }

        private void Quit(ActionEvent evt) {
            SwingUtilities.windowForComponent(this).dispose();
        }
    }

    public class Popup {

        private int type;

        public Popup(String softwareName) {
            if (softwareName.equals("Microsoft") || softwareName.equals("Norton") || softwareName.equals("Oracle") || softwareName.equals("CRM")) {
                if (softwareName.equals("Microsoft")) {
                    type = 1200000;
                } else if (softwareName.equals("Norton")) {
                    type = 3000000;
                } else if (softwareName.equals("Oracle")) {
                    type = 1700000;
                } else if (softwareName.equals("CRM")) {
                    type = 2300000;
                }
            }
        }

    }
}

【讨论】:

    【解决方案3】:

    试试下面的代码。

    Test.java

    import javax.swing.*;
    import java.awt.*;
    import javax.swing.event.*;
    
    public class Test
    {
        JFrame myMainWindow = new JFrame("This is my title");
        JPanel  firstPanel = new JPanel(null);
        JTextField textfield1 = new JTextField();
    
        public void runGUI() {
            myMainWindow.setBounds(10, 10, 500, 500);
            myMainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            myMainWindow.setLayout(new GridLayout(1,1));
            createFirstPanel();
            myMainWindow.getContentPane().add(firstPanel);
            myMainWindow.setVisible(true);
        }
    
        public void createFirstPanel() {
            textfield1.setBounds(335,102,90,35);
            textfield1.setBackground(new Color(255,255,255));
            textfield1.setForeground(new Color(0,0,0));
            textfield1.setEnabled(true);
            textfield1.setFont(new Font("sansserif",0,12));
            textfield1.setVisible(true);
            textfield1.getDocument().addDocumentListener(new MyDocumentListener());
            firstPanel.add(textfield1);
        }
    
        private class MyDocumentListener implements DocumentListener {
            public void insertUpdate(DocumentEvent e) {
                new Class2(textfield1.getText());
            }
    
            public void removeUpdate(DocumentEvent e) {
                new Class2(textfield1.getText());
            }
    
            public void changedUpdate(DocumentEvent e) {}
        }
    
        public static void main(String[] args)
        {
            Test t = new Test();
            t.runGUI();
        }
    }
    

    Class2.java

    public class Class2 {
        int software;
    
        public Class2(String s) {
            Company(s);
            System.out.println(s);
            System.out.println(software);
        }
    
        public void Company(String s) {
            if(s.equals("Microsoft")||s.equals("Norton")||s.equals("Oracle")||s.equals("CRM")){
                if(s.equals("Microsoft")) {
                    software = 1200000;
                    System.out.println("Matches Microsoft");
                } else if(s.equals("Norton")) {
                    software = 3000000;
                    System.out.println("Matches Norton");
                } else if(s.equals("Oracle")) {
                    software = 1700000;
                    System.out.println("Matches Oracle");
                } else if(s.equals("CRM")) {
                    software = 2300000;
                    System.out.println("Matches CRM");
                }
            } else {
                System.out.println("Not a company, GOOD BYE!");
            }
        }
    }
    

    我将KeyAdapter 更改为Document Listener,因为事件在更好的时间触发,即在文档更改之后。而在您的版本中,KeyAdapter 是在将字母放入 textfield1 之前触发事件。

    编辑

    如果您希望它在最后检查。删除Document Listener 并在Test.java 中添加以下代码

    导入 javax.swing.; 导入 java.awt.; 导入 javax.swing.event.; 导入 java.awt.event.;

    public class Test
    {
        JFrame myMainWindow = new JFrame("This is my title");
        JPanel  firstPanel = new JPanel(null);
        JTextField textfield1 = new JTextField();
        JButton button1 = new JButton("Check Company");
    
        public void runGUI() {
            myMainWindow.setBounds(10, 10, 500, 500);
            myMainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            myMainWindow.setLayout(new GridLayout(1,1));
            createFirstPanel();
            myMainWindow.getContentPane().add(firstPanel);
            myMainWindow.setVisible(true);
        }
    
        public void createFirstPanel() {
            textfield1.setBounds(335,102,90,35);
            textfield1.setBackground(new Color(255,255,255));
            textfield1.setForeground(new Color(0,0,0));
            textfield1.setEnabled(true);
            textfield1.setFont(new Font("sansserif",0,12));
            textfield1.setVisible(true);
            firstPanel.add(textfield1);
    
            button1.setBounds(335,150,150,35);
            button1.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent evt) {
                    new Class2(textfield1.getText());
                }
            });
            firstPanel.add(button1);
        }
    
        public static void main(String[] args)
        {
            Test t = new Test();
            t.runGUI();
        }
    }
    

    【讨论】:

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