我有一个有三个功能的程序;读取文件，写入文件并搜索文件中的特定文本。我正在创建一个与它一起使用的GUI，以便我不再依赖于控制台。我已经创建了一个功能齐全的“主窗口”和关于上述三个功能的功能按钮，以及一个退出按钮。现在我正在使用我的搜索功能的GUI窗口 - 创建窗口作为对单击的搜索按钮的响应。 我的窗口和组件按照我想要的方式布局，但是当用户在输入要搜索的字符串后按Enter键时，我无法设置动作监听器。 < / strong>我看了很多不同的资源，包括SOverflow，javadoc和actionlistener教程;但是我无处可去。
以下是在主窗口中绘制“搜索”按钮并链接到搜索GUI的基本代码（我通过main链接到此）：
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();
}
}
}
}
}
}
答案 0 :(得分：3)
您应该尝试重新构建代码
我不会在actionPerformed内创建GUI，在外面创建它（或者为它扩展JFrame创建一个类），而在actionPerformed中，只显示它setVisible(true)。
即使这个建议不是你的问题，它也许可以解决它。
您目前的情况是：
您正在将actionListener添加到JTextField searchTerm，您添加的actionListener实际上是ButtonClickListener，因此您已经拥有actionPerformed方法，因此同样的方法!!!
结果是：
当您在searchTerm按Enter键时，ButtonClickListener.actionPerformed会被调用，如果您尝试在文本字段中写“搜索”，您会看到有趣的内容 !! < / p>
添加新actionListener的简短代码是
searchTerm.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
//DO YOUR STUFF
}
});
答案 1 :(得分：1)
只需将此代码粘贴到构造函数中即可。
希望它会有所帮助。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);
}
});