クラスにリスナーを割り当てようとするときのトラブル

Question

私の問題は、不可解な無能さにあります。

ソフトウェアは、メインフレームと呼ばれるのJFrameの子クラスが複数にダイアログを聞いているJavaのSwingベースのデスクトップアプリケーションです。すべてのダイアログウィンドウは、リスナー関連の変数と関数を運ぶPDialogクラスの子です。だから私は、私は成功し、彼らがPDialogの子クラスとして継承された機能を使用してに耳を傾ける3つのダイアログを作成している

public class PDialog extends JDialog { 

private MainFrameChildrenListener listener; 

// Function that assigns its parameter to local listener value "listener setter" 
public void addMainFrameChildrenListener(MainFrameChildrenListener listener) { 
    this.listener = listener; 
} 

public void removeMainFrameChildrenListener() { 
    this.listener = null; 
} 

public void firePDialogEvent(MainFrameChildrenEventObject event) { 
    this.listener.dialogEventOccured(event); 
} 

// This method was useful when I tried to debug with System.out.println() method 
public String retrieveListenerInformation(){ 
    if(listener == null){ 
     return "No listener loaded"; 
    } 
    return this.listener.toString(); 
} 
} 

：これはPDialogクラスは次のようになります。メインフレームクラスはMainFrameChildrenListenerリスナーオブジェクトを実装し、それはそのコンストラクタでダイアログにリスナーとして渡されます。

public class MainFrame extends JFrame implements MainFrameChildrenListener { 

private PDialogCustomer dialogCustomer = new PDialogCustomer(); 
private PDialogOrder dialogOrder = new PDialogOrder(); 
private PDialogProduct dialogProduct = new PDialogProduct(); 
private PDialogMaterial dialogMaterial = new PDialogMaterial(); 

public MainFrame(){ 
    dialogMaterial.addMainFrameChildrenListener(this); 
    dialogCustomer.addMainFrameChildrenListener(this); 
    dialogOrder.addMainFrameChildrenListener(this); 
    dialogProduct.addMainFrameChildrenListener(this); 


    System.out.println("Material dialog: " + dialogMaterial.retrieveListenerInformation()); 
    System.out.println("Customer dialog: " + dialogCustomer.retrieveListenerInformation()); 
    System.out.println("Order dialog: " + dialogOrder.retrieveListenerInformation()); 
    System.out.println("Product dialog: " + dialogProduct.retrieveListenerInformation()); 
} 

驚くべきアプリケーションの起動後にコンソールがPDialog.retrieveListenerInformation（）命令を出力し、これはそれが見えるものです以下のような：私は火災リスナーイベントにしようとした場合

Material dialog: No listener loaded 
Customer dialog: view.MainFrame[-deleted the .toString() rubbish to keep things short-] 
Order dialog: view.MainFrame[-deleted the .toString() rubbish to keep things short-] 
Product dialog: view.MainFrame[-deleted the .toString() rubbish to keep things short-] 

そして、私はPDialog.firePDialogEvent（）メソッドのためnullポインタ例外を取得します。 リスナーをPDialogMaterialクラスのコンストラクタを介して渡そうとしましたが、PDialogMaterialクラス内で新しいメソッドを作成しようとしても、リスナーを渡すことはできませんでした。

public class PDialogMaterial extends PDialog{ 
public MainFrameChildrenListener testListener; 
} 

public class MainFrame extends JFrame implements MainFrameChildrenListener{ 
    public MainFrame(){ 
    dialogMaterial.testListener = this; 
    dialogCustomer.addMainFrameChildrenListener(this); 
    dialogOrder.addMainFrameChildrenListener(this); 
    dialogProduct.addMainFrameChildrenListener(this); 

    } 
} 

あります：私は物事を動作させることができた唯一の方法は、公共を宣言（！EEK）などは以下のようにメインフレームのコンストラクタから、それは直接（！eeeeek）にアクセスされた新しいMainFrameChildrenListener変数を作成しましたなぜすべて継承した4つのクラスのうちの3つがと同じかリスナハンドリングメソッドは4番目のクラスとは異なる振る舞いをしていますか？私は何が欠けていますか？

コメントフォロー：

PDialogMaterial（動作していない）の完全なコード：

package view.dialogs; 

import java.awt.Dimension; 
import java.awt.GridBagConstraints; 
import java.awt.GridBagLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.net.URL; 

import javax.swing.DefaultComboBoxModel; 
import javax.swing.ImageIcon; 
import javax.swing.JButton; 
import javax.swing.JComboBox; 
import javax.swing.JLabel; 
import javax.swing.JOptionPane; 
import javax.swing.JTextField; 

import view.listeners.MainFrameChildrenEventObject; 
import view.listeners.MainFrameChildrenListener; 
import view.utils.DoubleFormatCheck; 

public class PDialogMaterial extends PDialog { 
    private static final long serialVersionUID = 6190469565649183032L; 

    // private PMaterialFabricObject fabricObject; 

    public static final int FABRIC_MASK = 0; 
    public static final int STRAP_MASK = 1; 
    public static final int PARTS_MASK = 2; 
    public static final int THREAD_MASK = 3; 

    private String[] fabricMaterialList = { "Cotton", "Brocate", "Satin", "Synthetic" }; 
    private String[] fabricColorsList = { "Red", "Green", "Blue", "Purple", "Gray", "Yellow", "Black", "Khakhi", 
      "Carcaline" }; 

    private MainFrameChildrenListener listener; 

    private GridBagConstraints gc = new GridBagConstraints(); 

    private Dimension size = new Dimension(300, 300); 

    private DoubleFormatCheck dfc = new DoubleFormatCheck(); 

    private JTextField nameField = new JTextField(8); 
    private JTextField priceField = new JTextField(6); 
    private JTextField widthField = new JTextField(6); 
    private JTextField vendorField = new JTextField(8); 

    private JButton okButton = new JButton("Ok"); 
    private JButton cancelButton = new JButton("Cancel"); 

    private DefaultComboBoxModel<String> fabricMaterialComboBoxModel = new DefaultComboBoxModel<String>(
      fabricMaterialList); 
    private DefaultComboBoxModel<String> materialColorComboBoxModel = new DefaultComboBoxModel<String>(
      fabricColorsList); 
    private JComboBox<String> fabricMaterialComboBox = new JComboBox<String>(fabricMaterialComboBoxModel); 
    private JComboBox<String> fabricColorComboBox = new JComboBox<String>(materialColorComboBoxModel); 

    public PDialogMaterial(){ 

    } 

    public void addMainFrameChildrenListener(MainFrameChildrenListener listener) { 
     this.listener = listener; 
    } 

    public void removeMainFrameChildrenListener() { 
     this.listener = null; 
    } 

    public void firePDialogMaterialEventOccured(MainFrameChildrenEventObject event) { 
     this.listener.dialogEventOccured(event); 
    } 

    public ImageIcon getPicture(String path) { 
     URL link = this.getClass().getResource(path); 
     ImageIcon icon = new ImageIcon(link); 
     return icon; 
    } 

    public void setFabricMask() { 

     gc.gridx = 0; 
     gc.gridy = 0; 
     gc.gridwidth = 1; 
     gc.gridheight = 1; 
     gc.weightx = 1; 
     gc.weighty = 1; 
     gc.anchor = GridBagConstraints.CENTER; 

     // First line - picture 
     gc.gridwidth = 2; 

     this.add(new JLabel(getPicture("/images/material_32pos.gif")), gc); 

     gc.gridwidth = 1; 

     // Second line - name 
     gc.gridy++; 
     this.add(new JLabel("Name: "), gc); 

     gc.gridx++; 
     this.add(nameField, gc); 

     // Third line - material 
     gc.gridx--; 
     gc.gridy++; 
     this.add(new JLabel("Material: "), gc); 

     gc.gridx++; 
     this.add(fabricMaterialComboBox, gc); 

//  Fourth line - vendor name 
     gc.gridx--; 
     gc.gridy++; 
     this.add(new JLabel("Vendor: "), gc); 

     gc.gridx++; 
     this.add(vendorField, gc); 

     // Fifth line - predominating color 
     gc.gridx--; 
     gc.gridy++; 
     this.add(new JLabel("Predominaing color: "), gc); 

     gc.gridx++; 
     this.add(fabricColorComboBox, gc); 

     // Sixth line - price 
     gc.gridx--; 
     gc.gridy++; 
     this.add(new JLabel("Price per square meter: "), gc); 

     gc.gridx++; 
     this.add(priceField, gc); 

     // Seventh line - control buttons 
     gc.gridx--; 
     gc.gridy++; 
     this.add(okButton, gc); 

     gc.gridx++; 
     this.add(cancelButton, gc); 
    } 

    public void setStrapMask() { 
     gc.gridx = 0; 
     gc.gridy = 0; 
     gc.gridwidth = 1; 
     gc.gridheight = 1; 
     gc.weightx = 1; 
     gc.weighty = 1; 
     gc.anchor = GridBagConstraints.CENTER; 

     // First line - picture 
     gc.gridwidth = 2; 

     this.add(new JLabel(getPicture("/images/material_32pos.gif")), gc); 

     gc.gridwidth = 1; 

     // Second line - name 
     gc.gridy++; 
     this.add(new JLabel("Name: "), gc); 

     gc.gridx++; 
     this.add(nameField, gc); 

     // Third line - strap width 
     gc.gridx--; 
     gc.gridy++; 
     this.add(new JLabel("Width: "), gc); 

     gc.gridx++; 
     this.add(widthField, gc); 

     // Fourth line - predominating color 
     gc.gridx--; 
     gc.gridy++; 
     this.add(new JLabel("Predominaing color: "), gc); 

     gc.gridx++; 
     this.add(fabricColorComboBox, gc); 

     // Fifth line - strap price 
     gc.gridx--; 
     gc.gridy++; 
     this.add(new JLabel("Price per meter: "), gc); 

     gc.gridx++; 
     this.add(priceField, gc); 

     // Sixth line - control buttons 
     gc.gridx--; 
     gc.gridy++; 
     this.add(okButton, gc); 

     gc.gridx++; 
     this.add(cancelButton, gc); 
    } 

    public void constructPDialogMaterial(int maskType){ 
     this.setLayout(new GridBagLayout()); 
     this.setLocationRelativeTo(this.getParent()); 
     this.setDefaultCloseOperation(PDialog.DISPOSE_ON_CLOSE); 
     this.setSize(size); 
     this.setResizable(false); 
     this.setVisible(false); 
     this.setIconImage(getPicture("/images/material_32pos.gif").getImage()); 
     this.nameField.setBackground(this.getBackground()); 
     this.vendorField.setBackground(this.getBackground()); 
     this.priceField.setBackground(this.getBackground()); 

     switch (maskType) { 

     case PDialogMaterial.FABRIC_MASK: 
      this.setTitle("Fabric material"); 
      setFabricMask(); 
      break; 

     case PDialogMaterial.STRAP_MASK: 
      this.setTitle("Straps"); 
      setStrapMask(); 
      break; 

     // TODO 
     default: 
      System.out.println("Oh noes! Something happend!"); 
     } 

     okButton.addActionListener(new ActionListener() { 
      public void actionPerformed(ActionEvent event) { 

       String priceString = dfc.removeWhitespacesAndSwapCommas(priceField.getText()); 

       if(dfc.testDoubleFormat(priceString)){ 

        Double price = Double.valueOf(priceString); 

        MainFrameChildrenEventObject eventObject = new MainFrameChildrenEventObject(okButton, vendorField.getText(), nameField.getText(), 
          (String)materialColorComboBoxModel.getSelectedItem(), (String)materialColorComboBoxModel.getSelectedItem(), 
          price, PDialog.MATERIAL_EVENT_FABRIC); 

        firePDialogEvent(eventObject); 

        dispose(); 
       } 

       else{ 
        JOptionPane.showMessageDialog(PDialogMaterial.this, "Wrong price format", "Format error", 
          JOptionPane.WARNING_MESSAGE); 
       } 
      } 
     }); 

     cancelButton.addActionListener(new ActionListener() { 
      public void actionPerformed(ActionEvent arg0) { 
       dispose(); 
      } 
     }); 
    } 
} 

PDialogCustomer（実施例）の完全なコード：

 package view.dialogs; 

import java.awt.GridBagConstraints; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.net.URL; 

import javax.swing.BorderFactory; 
import javax.swing.ImageIcon; 
import javax.swing.JButton; 
import javax.swing.JLabel; 
import javax.swing.JTextField; 

import view.listeners.MainFrameChildrenEventObject; 

public class PDialogCustomer extends PDialog { 
    private static final long serialVersionUID = 8431597688560531951L; 

    private GridBagConstraints gc = new GridBagConstraints(); 

    private URL imageLink; 
    private URL iconLink; 

    // New customer GUI setup 
    JLabel nameLabel = new JLabel("Customer name: "); 
    JLabel addressLabel = new JLabel("Customer address: "); 
    JLabel dogLabel = new JLabel("Dog name: "); 
    JTextField nameField = new JTextField(8); 
    JTextField streetField = new JTextField(8); 
    JTextField cityField = new JTextField(8); 
    JTextField countryField = new JTextField(8); 
    JTextField dogField = new JTextField(8); 
    JButton okBttn = new JButton("Ok"); 
    JButton cancelBttn = new JButton("Cancel"); 

    // ________________________________________________________ 

    public PDialogCustomer() { 

     String imagePath = "/images/customer_32pos.gif"; 
     String iconPath = "/images/customer_16pos.gif"; 

     this.iconLink = getClass().getResource(iconPath); 
     this.setIconImage(new ImageIcon(iconLink).getImage()); 
     this.imageLink = getClass().getResource(imagePath); 
     this.setTitle("New customer"); 

     nameField.setBorder(BorderFactory.createEtchedBorder()); 
     nameField.setBackground(this.getBackground()); 
     streetField.setBorder(BorderFactory.createTitledBorder("Street")); 
     streetField.setBackground(this.getBackground()); 
     cityField.setBorder(BorderFactory.createTitledBorder("City")); 
     cityField.setBackground(this.getBackground()); 
     countryField.setBorder(BorderFactory.createTitledBorder("Country")); 
     countryField.setBackground(this.getBackground()); 
     dogField.setBorder(BorderFactory.createTitledBorder("Dogs name")); 
     dogField.setBackground(this.getBackground()); 

     gc.weightx = 1; 
     gc.weighty = 1; 
     gc.gridheight = 1; 
     gc.gridwidth = 2; 
     gc.gridx = 0; 
     gc.gridy = 0; 
     gc.anchor = GridBagConstraints.CENTER; 

     add(new JLabel(new ImageIcon(imageLink))); 

     gc.gridwidth = 1; 
     gc.gridy++; 
     add(nameLabel, gc); 

     gc.gridx++; 
     add(nameField, gc); 

     gc.gridy++; 
     gc.gridx--; 
     add(addressLabel, gc); 

     gc.gridx++; 
     add(streetField, gc); 

     gc.gridy++; 
     add(cityField, gc); 

     gc.gridy++; 
     add(countryField, gc); 

     gc.gridy++; 
     gc.gridx--; 
     add(dogLabel, gc); 

     gc.gridx++; 
     add(dogField, gc); 

     gc.gridy++; 
     gc.gridx--; 
     add(okBttn, gc); 

     gc.gridx++; 
     add(cancelBttn, gc); 

     okBttn.addActionListener(new ActionListener() { 
      public void actionPerformed(ActionEvent e) { 
       String address = streetField.getText() + ", " + cityField.getText() + ", " + countryField.getText(); 
       firePDialogEvent(new MainFrameChildrenEventObject(okBttn, nameField.getText(), address, 
         dogField.getText(), PDialog.CUSTOMER_EVENT)); 
       dispose(); 
      } 
     }); 

     cancelBttn.addActionListener(new ActionListener() { 
      public void actionPerformed(ActionEvent e) { 
       dispose(); 
      } 
     }); 
    } 
} 

Answer 1

問題における問題クラスはそれを再宣言することです

private MainFrameChildrenListener listener; 

フィールド。したがって、スーパークラスには2つのプライベートフィールドがあり、サブクラスには同じ名前のプライベートフィールドが2つあります。サブクラス内のメソッドは、そのサブクラスのメソッドにあるときにスーパークラスのメソッドをオーバーライドしますが、スーパークラスに定義されているメソッドでは表示されません。サブクラスのリスナーフィールドを削除すると、正常に動作するはずです。

Answer 2

Markusすでに言われているように、機能していないリスナーでは、リスナーフィールドを隠していて、セッターを再宣言しています。// WWW：早く、[MCVE]または[ショート、自炊、正しい例]（HTTPを投稿

import java.util.Arrays; 

public class HiddenField { 

    static abstract class Base { 
     String field = "BASE"; 

     // sets the base's field 
     void setField(String set) { 
      this.field = set; 
     } 

     // ensures not to be overridden and returns the base's field. 
     final String getField() { 
      return this.field; 
     } 

     // access the field by getter (ensured to be base) and field 'field' 
     @Override 
     public String toString() { 
      return this.getClass().getSimpleName() + ": get()->" + getField() + " vs. field->" + field; 
     } 
    } 

    static class ProperExtension extends Base { 
     /* no need to override the base's field */ 
    } 

    static class HidingExtension extends Base { 

     // this field isn't related to the one in Base, but has the same name! 
     String field = "HIDING"; 

     // the setter is overridden (exact copy!) but because of the same-named 
     // field in this extending class, it sets this class's field and not the 
     // one in the base-class! 
     @Override 
     void setField(String set) { 
      this.field = set; 
     } 

     // copied the toString from above - here it is accessing the 
     // base-class's field via getter and this class's field directly. 
     @Override 
     public String toString() { 
      return this.getClass().getSimpleName() + ": get()->" + getField() + " vs. field->" + field; 
     } 
    } 

    public static void main(String[] args) { 
     // build both types of extending classes and invoke their setters 
     Arrays.asList(new ProperExtension(), new HidingExtension()).forEach(obj -> { 
      System.out.println("before ~> " + obj); 
      obj.setField("SET"); 
      System.out.println("after ~> " + obj + "\n"); 
     }); 
    } 
}