ActionListener嵌套在ActionListener中？

Question

我有一个程序，它有三个功能:读取一个文件，写入一个文件，并在一个文件中搜索特定的文本。我目前正在创建一个GUI，以便不再依赖控制台。我已经为上述三个函数创建了一个功能齐全的“主窗口”和功能按钮，以及一个退出按钮。现在，我正在处理我的搜索功能的GUI窗口-该窗口是创建为响应被点击的搜索按钮。，我有窗口和组件按我想要的方式布局，但是当用户输入他们想要搜索的字符串后，当用户按Enter时，设置动作监听器会有困难。我看过许多不同的源，包括SOverflow、javadoc和actionlistener教程；但是我没有进展很快。

下面是在主窗口中绘制搜索按钮的基本代码，并链接到Search (我通过main链接到它)：

public class SimpleDBGUI{
    static File targetFile;                                                                                         //Declare File var to be used in methods below for holding user's desired file
    static JTextField sdbTarget;
    static JTextField searchTerm;


    public void mainWindow(){

        //Create main window for Program
        JFrame mainWindow = new JFrame("Simple Data Base");                                                         //Init frame
        mainWindow.setSize(500, 180);                                                                               //Set frame size
        mainWindow.setVisible(true);                                                                                //Make frame visible

        //Create panel for the main window of the GUI
        JPanel simpleGUI = new JPanel( new GridBagLayout());
        GridBagConstraints gbCons = new GridBagConstraints();
        mainWindow.getContentPane().add(simpleGUI);                                                                 //Adds JPanel container to the ContentPane of the JFrame

        //Create button linking to the search function
        JButton searchButton = new JButton("Search");                                                               //Init button with text
        gbCons.fill = GridBagConstraints.BOTH;
        gbCons.gridx = 1;
        gbCons.gridy = 2;
        gbCons.weightx = .1;
        searchButton.setActionCommand("Search");
        searchButton.addActionListener( new ButtonClickListener());
        simpleGUI.add(searchButton, gbCons);                                                                        //Adds the "Search" button to the JPanel

        //Create TextField for user to input a desired file
        sdbTarget = new JTextField();
        gbCons.fill = GridBagConstraints.BOTH;
        gbCons.gridx = 0;
        gbCons.gridy = 1;
        gbCons.gridwidth = 3;
        simpleGUI.add(sdbTarget, gbCons);                                                                           //Adds TextField to GUI
    }

    public class ButtonClickListener implements ActionListener{                                                     //Sets the EventListener for every function

        public void actionPerformed(ActionEvent event){

            targetFile = new File(sdbTarget.getText());
            String function = event.getActionCommand();                                                             //Reads the ActionCommand into a string for use in performing desired function

            if( function.equals("Search")){                                                                         //Search Function, draws search window and components
                JFrame searchWindow = new JFrame("SimpleDB Search");                                                //Draw window
                searchWindow.setSize(500, 200);
                searchWindow.setVisible(true);

                JPanel searchGUI = new JPanel( new GridBagLayout());                                                //Create container and add to window 
                GridBagConstraints gb1Cons = new GridBagConstraints();
                searchWindow.getContentPane().add(searchGUI);

                JLabel searchPrompt = new JLabel("Please input the word/phrase you wish to find:");                 //Prompt user to specify string to search for
                gb1Cons.fill = GridBagConstraints.BOTH;
                gb1Cons.gridy = 0;
                gb1Cons.gridx = 0;
                //gb1Cons.weighty = .1;
                searchGUI.add(searchPrompt, gb1Cons);                                                               //Add prompt to container

                JTextField searchTerm = new JTextField();                                                           //Create JTextField for user input and add to container
                gb1Cons.fill = GridBagConstraints.BOTH;
                gb1Cons.gridy = 1;
                gb1Cons.gridx = 0;
                //gb1Cons.weighty = .1;
                searchGUI.add(searchTerm, gb1Cons); 
                searchTerm.addActionListener(this);                                                                 //Assign ActionListener to JTextField

                JTextArea searchResult = new JTextArea();                                                           //Create search output box and add to container
                gb1Cons.fill = GridBagConstraints.BOTH;
                gb1Cons.gridy = 2;
                gb1Cons.gridx = 0;
                //gb1Cons.weighty = .1;
                searchGUI.add(searchResult, gb1Cons);

                public void actionPerformed( ActionEvent event){        //Tried this as one event handler, supposed to execute the following upon the user pressing Enter, failed of course

                    boolean stringFound = false;                                                                    //Set flag false
                    try{
                        Scanner searchFile = new Scanner(targetFile);                                               //Read file to be searched into a scanner
                        String searchInput = searchTerm.getText();                                                  //Read term to search for into a string

                        while( searchFile.hasNextLine()){                                                           //Check that specified file has a next line and:
                            String searchLine = searchFile.nextLine();                                                  //Read line into string
                            if( searchLine.contains(searchInput)){                                                      //Check that Line contains searched term and:
                                stringFound = true;                                                                         //If line contains term, set flag to true
                                searchResult.append("**" + searchLine + "**");                                              //Append line with term to output box
                            }
                        }searchFile.close();                                                                        //Close scanner

                        if(!stringFound){
                            searchResult.append("The term(s) you searched for does not exist in this file");        //Output if line does not contain term
                        }
                    }catch(IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }
    }
}

Answer 1

您应该尝试重新构造代码

我不会在actionPerformed中创建GUI，也不会在外部创建GUI(或者为其扩展JFrame创建类)，而在actionPerformed中，只需显示setVisible(true)即可。

即使这个建议不是你的问题，它也可能解决它。

当前的情况是：

您要将actionListener添加到JTextField searchTerm中，而您要添加的actionListener实际上是ButtonClickListener，因此您已经有了一个actionPerformed方法，因此使用相同的方法！

所以结果是：：

当您在searchTerm中按enter键时，ButtonClickListener.actionPerformed将被调用，如果您试图在textfield中编写"Search“，您将看到--一些有趣的！！

添加新actionListener的简短代码将是

searchTerm.addActionListener(new ActionListener() {
  public void actionPerformed(ActionEvent e) {
    //DO YOUR STUFF
  }
});

Answer 2

只需将此代码粘贴到构造函数中即可。

希望能帮上忙。请记住，您的searchTerm应该是jtextfield，因为jtextxarea的代码有点不同。

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