java - Jframe错误: Exception: “AWT-EventQueue-0” java.lang.NullPointerException

Question

我正在尝试创建一个使用jframe将普通文本转换为二进制文件的应用程序。我的代码找不到任何错误，但仍然会输出错误，并且当我尝试运行它时应用程序无法正常工作。

我的代码:

package japplet;

public class Translator extends javax.swing.JFrame {

    /**
     * Creates new form Translator
     */
    public Translator() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jScrollPane2 = new javax.swing.JScrollPane();
        Output = new javax.swing.JTextArea();
        Translate = new javax.swing.JButton();
        Reset = new javax.swing.JButton();
        User_InputBox = new javax.swing.JTextField();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        Output.setEditable(false);
        Output.setColumns(20);
        Output.setRows(5);
        jScrollPane2.setViewportView(Output);

        Translate.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
        Translate.setText("Translate");
        Translate.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                TranslateActionPerformed(evt);
            }
        });

        Reset.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
        Reset.setText("Reset");
        Reset.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                ResetActionPerformed(evt);
            }
        });

        User_InputBox.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                User_InputBoxActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                    .addComponent(jScrollPane2, javax.swing.GroupLayout.DEFAULT_SIZE, 405, Short.MAX_VALUE)
                    .addComponent(User_InputBox))
                .addGap(80, 80, 80)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(Translate, javax.swing.GroupLayout.DEFAULT_SIZE, 111, Short.MAX_VALUE)
                    .addComponent(Reset, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(64, 64, 64)
                        .addComponent(Translate, javax.swing.GroupLayout.PREFERRED_SIZE, 62, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(layout.createSequentialGroup()
                        .addContainerGap()
                        .addComponent(User_InputBox, javax.swing.GroupLayout.PREFERRED_SIZE, 138, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 151, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(31, 31, 31)
                        .addComponent(Reset, javax.swing.GroupLayout.PREFERRED_SIZE, 61, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(33, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        

    private void TranslateActionPerformed(java.awt.event.ActionEvent evt) {                                          
        String UserInputBox = User_InputBox.getSelectedText();
        TranslateInput(UserInputBox);
    }                                         

    private void ResetActionPerformed(java.awt.event.ActionEvent evt) {                                      
        User_InputBox.setText("");
        Output.setText("");
    }                                     

    private void User_InputBoxActionPerformed(java.awt.event.ActionEvent evt) {                                              
        // TODO add your handling code here:
    }                                             

    private void TranslateInput(String input) {
        String ascii[] = {" ","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","0","1","2","3","4","5","6","7","8","9",};
        String binaryCode[] = {"00100000", "01100001","01100010","01100011","01100100","01100101","01100110","01100111","01101000","01101001","01101010","01101011","01101100","01101101","01101110","01101111","01110000","01110001","01110010","01110010","01110011","01110100","01110101","01110110","01110111","01111000","01111001","01111010","01000001","01000010","01000011","01000100","01000101","01000110","01000111","01001000","01001001","01001010","01001100","01001101","01001110","01001111","01010000","01010001","01010010","01010011","01010100","01010101","01010110","01010111","01011000","01011001","01011010","00110000","00110001","00110010","00110011","00110100","00100101","00100110","00100111","00101000","001010001"};
        String storage[] = {"1"};
        int storageNo = 0;
        for (int a = 0; a <= input.length();a++) {
            char text = input.charAt(a);
            String stringText = String.valueOf(text);
            for (int numbering = 0;numbering <= (ascii.length-1);numbering++) {
                if (stringText == ascii[numbering]) {
                    storage[storageNo] = binaryCode[numbering];
                    storageNo++;
                    storage[storageNo] = " ";
                    storageNo++;
                } else {

                }
            }
        }
        for (int as = 0;as < storage.length;as++) {
            Output.append(storage[as]);
        }
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Translator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Translator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Translator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Translator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Translator().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JTextArea Output;
    private javax.swing.JButton Reset;
    private javax.swing.JButton Translate;
    private javax.swing.JTextField User_InputBox;
    private javax.swing.JScrollPane jScrollPane2;
    // End of variables declaration                   
}

我的错误:

    run:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at japplet.Translator.TranslateInput(Translator.java:121)
    at japplet.Translator.TranslateActionPerformed(Translator.java:104)
    at japplet.Translator.access$000(Translator.java:12)
    at japplet.Translator$1.actionPerformed(Translator.java:47)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6533)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at java.awt.Component.processEvent(Component.java:6298)
    at java.awt.Container.processEvent(Container.java:2237)
    at java.awt.Component.dispatchEventImpl(Component.java:4889)
    at java.awt.Container.dispatchEventImpl(Container.java:2295)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4889)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4526)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4467)
    at java.awt.Container.dispatchEventImpl(Container.java:2281)
    at java.awt.Window.dispatchEventImpl(Window.java:2746)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.awt.EventQueue$4.run(EventQueue.java:729)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
BUILD SUCCESSFUL (total time: 5 seconds)

注意:我是Java新手，在尝试将其发布到这里之前，曾尝试过使用google。
希望能得到一些好的建议，并请您原谅我一些基本的错误。谢谢

编辑:将 String UserInputBox = User_InputBox.getSelectedText();编辑为 String UserInputBox = User_InputBox.getText();之后。错误变为:

run:
Exception in thread "AWT-EventQueue-0" java.lang.StringIndexOutOfBoundsException: String index out of range: -1
    at java.lang.String.charAt(String.java:658)
    at japplet.Translator.TranslateInput(Translator.java:122)
    at japplet.Translator.TranslateActionPerformed(Translator.java:104)
    at japplet.Translator.access$000(Translator.java:12)
    at japplet.Translator$1.actionPerformed(Translator.java:47)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6533)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at java.awt.Component.processEvent(Component.java:6298)
    at java.awt.Container.processEvent(Container.java:2237)
    at java.awt.Component.dispatchEventImpl(Component.java:4889)
    at java.awt.Container.dispatchEventImpl(Container.java:2295)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4889)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4526)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4467)
    at java.awt.Container.dispatchEventImpl(Container.java:2281)
    at java.awt.Window.dispatchEventImpl(Window.java:2746)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.awt.EventQueue$4.run(EventQueue.java:729)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
BUILD SUCCESSFUL (total time: 7 seconds)

Answer 1

得到我的答案，只是更改了字符串UserInputBox = User_InputBox.getSelectedText();到UserInputBox = User_InputBox.getText();

但是这里出现了另一个问题，将打开一个新线程。