我的GroceryList程序中没有输出

问题描述：

我得到的建议不像我一样使用静态，我误用了固有的内容之后重写了我的第一个应用程序。但现在我的应用程序不再工作了。我的GroceryList程序中没有输出

而我不明白为什么不。我想我会犯错误的东西，但看不到哪些东西。我读了关于stackoverflow和其他网站上的instanciation，但我仍然不完全理解它。

我是新来的java，不要编码那么久。我在Netbeans中构建了一个布局。每次你点击“添加”按钮杂货项目应显示在textarea。我的旧代码（所有东西都是静态的）工作正常。

我现在然后得到一个“线程中的异常”AWT-EventQueue-0“java.lang.ClassCastException：java.lang.Boolean不能转换为java.awt.Color”错误。但它不会一直出现。如果我不知道这个错误，我点击“添加”按钮就会发生。

有人能告诉我我做错了什么吗？

任何有关我在做什么错误或如何调试的建议将不胜感激。

GroceryList2ActionListener.java

package javaclasses; 
    import java.awt.event.ActionEvent; 
    import java.awt.event.ActionListener; 
    import grocerylist2jframe.GroceryList2JFrame; 

    // this is the ActionListener for adding a grocery item 
    public class GroceryList2ActionListener { 
     public void getButtonActionAddGroceryItem() { 
     GroceryList2JFrame jFrameAdd = new GroceryList2JFrame(); 
      jFrameAdd.buttonAddGroceryItem.addActionListener(new ActionListener() { 

       @Override 
       public void actionPerformed(ActionEvent e) { 
        String groceryItem = jFrameAdd.jTextField1GroceryItem.getText(); 
        String quantity = jFrameAdd.jTextField2Quantity.getText(); 
        String unit = jFrameAdd.jComboBox1Unit.getSelectedItem().toString(); 
        jFrameAdd.jTextArea1.append(groceryItem + " " + quantity + " " + unit + "\n"); 
       } 
      }); 
     } 
     // this is the ActionListener for removing a grocery item 
     public void getButtonActionRemoveGroceryItem() { 
      GroceryList2JFrame jFrameRemove = new GroceryList2JFrame(); 
      jFrameRemove.buttonRemoveGroceryItem.addActionListener(new ActionListener() { 
       @Override 
       public void actionPerformed(ActionEvent e) { 
        jFrameRemove.jTextArea1.setText(jFrameRemove.jTextArea1.getText().replaceAll(jFrameRemove.jTextArea1.getSelectedText(),"")); 
       } 
      }); 
     } 

     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 | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) { 
       java.util.logging.Logger.getLogger(GroceryList2JFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
      } 
      //</editor-fold> 
      //</editor-fold> 
      /* Create and display the form */ 
      java.awt.EventQueue.invokeLater(new Runnable() { 
       @Override 
       public void run() { 
        new GroceryList2JFrame().setVisible(true); 
       } 
      }); 
      GroceryList2ActionListener action = new GroceryList2ActionListener(); 
      action.getButtonActionAddGroceryItem(); // I think I call here the "addItem" and "removeItem" on button click. 
      action.getButtonActionRemoveGroceryItem(); 
     } 
    }

这是我写的的ActionListener。接下来是我在Netbeans中创建的应用程序的布局。我没有自己写过，我为此使用了JForm。

GroceryList2JFrame.java

package grocerylist2jframe; 

public class GroceryList2JFrame extends javax.swing.JFrame { 

    /** 
    * Creates new form GroceryList2JFrame 
    */ 
    public GroceryList2JFrame() { 
     initComponents(); 
    } 

    @SuppressWarnings("unchecked") 
    // <editor-fold defaultstate="collapsed" desc="Generated Code">       
    private void initComponents() { 

     jPanel1 = new javax.swing.JPanel(); 
     jPanel2 = new javax.swing.JPanel(); 
     jLabel2 = new javax.swing.JLabel(); 
     jLabel1 = new javax.swing.JLabel(); 
     jLabel3 = new javax.swing.JLabel(); 
     jComboBox1Unit = new javax.swing.JComboBox(); 
     jTextField2Quantity = new javax.swing.JTextField(); 
     jTextField1GroceryItem = new javax.swing.JTextField(); 
     jPanel3 = new javax.swing.JPanel(); 
     jPanel4 = new javax.swing.JPanel(); 
     jScrollPane1 = new javax.swing.JScrollPane(); 
     jTextArea1 = new javax.swing.JTextArea(); 

     setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 
     setSize(new java.awt.Dimension(0, 0)); 

     jPanel1.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "Grocerylist2", javax.swing.border.TitledBorder.DEFAULT_JUSTIFICATION, javax.swing.border.TitledBorder.DEFAULT_POSITION, new java.awt.Font("Georgia", 3, 18))); // NOI18N 
     jPanel1.setFont(new java.awt.Font("Georgia", 1, 11)); // NOI18N 

     jPanel2.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "Grocerylist Input", javax.swing.border.TitledBorder.DEFAULT_JUSTIFICATION, javax.swing.border.TitledBorder.DEFAULT_POSITION, new java.awt.Font("Georgia", 3, 14))); // NOI18N 

     jLabel2.setFont(new java.awt.Font("Georgia", 1, 11)); // NOI18N 
     jLabel2.setText("Choose a Quantity"); 

     jLabel1.setFont(new java.awt.Font("Georgia", 1, 11)); // NOI18N 
     jLabel1.setText("Add a Grocery Item"); 

     jLabel3.setFont(new java.awt.Font("Georgia", 1, 11)); // NOI18N 
     jLabel3.setText("Choose A Unit"); 

     jComboBox1Unit.setFont(new java.awt.Font("Georgia", 1, 11)); // NOI18N 
     jComboBox1Unit.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Kilogram", "Gram", "Liter", "Millilitre", "Piece(s)" })); 
     jComboBox1Unit.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       jComboBox1UnitActionPerformed(evt); 
      } 
     }); 

     jTextField2Quantity.setFont(new java.awt.Font("Georgia", 0, 9)); // NOI18N 
     jTextField2Quantity.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       jTextField2QuantityActionPerformed(evt); 
      } 
     }); 

     jTextField1GroceryItem.setFont(new java.awt.Font("Georgia", 0, 9)); // NOI18N 
     jTextField1GroceryItem.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       jTextField1GroceryItemActionPerformed(evt); 
      } 
     }); 

     buttonAddGroceryItem.setFont(new java.awt.Font("Georgia", 1, 14)); // NOI18N 
     buttonAddGroceryItem.setText("Add Grocery Item To Grocerylist"); 
     buttonAddGroceryItem.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       buttonAddGroceryItemActionPerformed(evt); 
      } 
     }); 

     buttonRemoveGroceryItem.setFont(new java.awt.Font("Georgia", 1, 14)); // NOI18N 
     buttonRemoveGroceryItem.setText("Remove Grocery Item From Gocerylist"); 

     javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2); 
     jPanel2.setLayout(jPanel2Layout); 
     jPanel2Layout.setHorizontalGroup(
      jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(jPanel2Layout.createSequentialGroup() 
       .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false) 
        .addComponent(jLabel3, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
        .addComponent(jLabel1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 135, Short.MAX_VALUE) 
        .addComponent(jLabel2, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)) 
       .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
       .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
        .addComponent(jTextField1GroceryItem) 
        .addComponent(jTextField2Quantity) 
        .addComponent(jComboBox1Unit, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))) 
      .addComponent(buttonAddGroceryItem, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
      .addComponent(buttonRemoveGroceryItem, javax.swing.GroupLayout.DEFAULT_SIZE, 338, Short.MAX_VALUE) 
     ); 
     jPanel2Layout.setVerticalGroup(
      jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(jPanel2Layout.createSequentialGroup() 
       .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
        .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE) 
        .addComponent(jTextField1GroceryItem, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE)) 
       .addGap(10, 10, 10) 
       .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING) 
        .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE) 
        .addComponent(jTextField2Quantity, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE)) 
       .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
       .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
        .addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE) 
        .addComponent(jComboBox1Unit, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE)) 
       .addGap(86, 86, 86) 
       .addComponent(buttonAddGroceryItem, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) 
       .addComponent(buttonRemoveGroceryItem, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addContainerGap(217, Short.MAX_VALUE)) 
     ); 

     javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3); 
     jPanel3.setLayout(jPanel3Layout); 
     jPanel3Layout.setHorizontalGroup(
      jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGap(0, 0, Short.MAX_VALUE) 
     ); 
     jPanel3Layout.setVerticalGroup(
      jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGap(0, 0, Short.MAX_VALUE) 
     ); 

     jPanel4.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "Grocerylist2 View", javax.swing.border.TitledBorder.DEFAULT_JUSTIFICATION, javax.swing.border.TitledBorder.DEFAULT_POSITION, new java.awt.Font("Georgia", 1, 14))); // NOI18N 

     jTextArea1.setColumns(20); 
     jTextArea1.setFont(new java.awt.Font("Georgia", 1, 11)); // NOI18N 
     jTextArea1.setRows(5); 
     jScrollPane1.setViewportView(jTextArea1); 

     javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4); 
     jPanel4.setLayout(jPanel4Layout); 
     jPanel4Layout.setHorizontalGroup(
      jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 391, Short.MAX_VALUE) 
     ); 
     jPanel4Layout.setVerticalGroup(
      jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addComponent(jScrollPane1) 
     ); 

     javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1); 
     jPanel1.setLayout(jPanel1Layout); 
     jPanel1Layout.setHorizontalGroup(
      jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(jPanel1Layout.createSequentialGroup() 
       .addContainerGap() 
       .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
       .addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
       .addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)) 
     ); 
     jPanel1Layout.setVerticalGroup(
      jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
      .addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
      .addComponent(jPanel4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
     ); 

     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(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
       .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)) 
     ); 
     layout.setVerticalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(layout.createSequentialGroup() 
       .addGap(13, 13, 13) 
       .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
       .addContainerGap()) 
     ); 

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

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

    private void jTextField1GroceryItemActionPerformed(java.awt.event.ActionEvent evt) {              
     // TODO add your handling code here: 
    }              

    private void jTextField2QuantityActionPerformed(java.awt.event.ActionEvent evt) {              
     // TODO add your handling code here: 
    }             

    private void jComboBox1UnitActionPerformed(java.awt.event.ActionEvent evt) {            
     // TODO add your handling code here: 
    }            

    /** 
    * @param args the command line arguments 
    */ 


    // Variables declaration - do not modify      
    public final javax.swing.JButton buttonAddGroceryItem = new javax.swing.JButton(); 
    public final javax.swing.JButton buttonRemoveGroceryItem = new javax.swing.JButton(); 
    public javax.swing.JComboBox jComboBox1Unit; 
    private javax.swing.JLabel jLabel1; 
    private javax.swing.JLabel jLabel2; 
    private javax.swing.JLabel jLabel3; 
    private javax.swing.JPanel jPanel1; 
    private javax.swing.JPanel jPanel2; 
    private javax.swing.JPanel jPanel3; 
    private javax.swing.JPanel jPanel4; 
    private javax.swing.JScrollPane jScrollPane1; 
    public javax.swing.JTextArea jTextArea1; 
    public javax.swing.JTextField jTextField1GroceryItem; 
    public javax.swing.JTextField jTextField2Quantity; 
    // End of variables declaration     
}

答

我想你已经过于复杂的这一计划。其他SO用户是正确的，你应该避免使用静态方法和变量，除非有绝对的理由。您应该阅读一些关于Java Swing事件处理的内容，特别是如何使用ActionListener。

对于您的情况，您不需要单独的类（GroceryList2ActionListener），因为NetBeans正在为您的（通常）创建事件处理方法。 GroceryList2JFrame已经有一个方法来处理添加杂货商品。出于某种原因，当您添加删除按钮时，您在构建表单时没有选择添加动作侦听器。

此外，是有意义的有一个“司机”类主要以实例化框架，设置一下正的感觉，等

1）您可以删除/删除GroceryList2ActionListener类 - 这是不再需要。

2）将此课程添加到与您的GroceryList2JFrame课程相同的包中。这是现在具有main（）方法的驱动程序类。

package grocerylist2jframe; 


    public class GroceryList { 
     public static void main(String args[]) { 
      System.out.println("Running the GroceryList program..."); 
       /* 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 | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) { 
       java.util.logging.Logger.getLogger(GroceryList2JFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
      } 
      //</editor-fold> 
      //</editor-fold> 
       /* Create and display the form */ 
      java.awt.EventQueue.invokeLater(new Runnable() { 
       @Override 
       public void run() { 
        GroceryList2JFrame frame = new GroceryList2JFrame(); 
        frame.setVisible(true); 
       } 
      }); 
     } 
    }

3）当使用NetBeans构建形式时，其已添加的事件处理程序的方法和注册它添加按钮，但它是为删除按钮删去。如果环顾GroceryList2JFrame类的第70行，您将看到方法调用buttonAddGroceryItem.addActionListener()...我添加了一个类似的块来为buttonRemoveGroceryItem注册新方法。将这段代码放在`buttonAddGroceryItem下面。addActionListener方法（）代码：

buttonRemoveGroceryItem.setFont(new java.awt.Font("Georgia", 1, 14)); // NOI18N 
    buttonRemoveGroceryItem.setText("Remove Grocery Item From Gocerylist"); 
    buttonRemoveGroceryItem.addActionListener(new java.awt.event.ActionListener(){ 
     public void actionPerformed(java.awt.event.ActionEvent evt){ 
      buttonRemoveGroceryItemActionPerformed(evt); 
     } 
    });

最后，你会发现现有的方法GroceryList2JFrame.buttonAddGroceryItemActionPerformed()，这是由NetBeans中创建的。我已经填写的方法，复制从GroceryList2ActionLIstener内容，还增加了一种用于buttonRemoveGroceryItemActionPerformed()，两者如下所示：

private void buttonAddGroceryItemActionPerformed(java.awt.event.ActionEvent evt) { 
    String groceryItem = jTextField1GroceryItem.getText(); 
    String quantity = jTextField2Quantity.getText(); 
    String unit = jComboBox1Unit.getSelectedItem().toString(); 
    jTextArea1.append(groceryItem + " " + quantity + " " + unit + "\n"); 
} 

private void buttonRemoveGroceryItemActionPerformed(java.awt.event.ActionEvent evt){ 
    String choice = jTextArea1.getSelectedText(); 
    try { 
     jTextArea1.setText(jTextArea1.getText().replaceAll(choice, "")); 
    } 
    catch(Exception ex){ 
     JOptionPane.showMessageDialog(this, "Please select a valid item from the grocery list before clicking to remove.", 
       "Invalid Item selected for removal", JOptionPane.ERROR_MESSAGE); 
    } 
}

一旦你取得了这些细微的变化，你的程序应该正常工作。祝你好运！

非常感谢。我显然有很多要学习:) –

我的GroceryList程序中没有输出

相关推荐