java - 从文本文件中搜索字符串(不区分大小写)

Question

我正在用 Java 做我的论文。我被困在某一点上。我无法让工作从文件中搜索字符串。我需要从文件中搜索用户输入的单词，即使文件中的字符串是“F”并且他输入“f”我也必须得到响应。做到这一点的最佳方法是什么？这是实现这种目标的最佳方式吗？如果我错了，也许最好使用 ArrayList 来纠正我。

这是我到目前为止所做的:

 JButton btnTuletaParoolMeelde = new JButton("Tuleta parool meelde");
 btnTuletaParoolMeelde.setBackground(new Color(37, 209, 175));
 btnTuletaParoolMeelde.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent e) {


            //Search
            String keskkond = textArea.getText();

            if(keskkond.length()<=0){
                System.out.println("You didn't enter anything");
            }else{
               int tokencount;
               FileReader filereader = null;
            try {
                filereader = new FileReader("paroolid.txt");
            } catch (FileNotFoundException e2) {
                // TODO Auto-generated catch block
                e2.printStackTrace();
            }
               BufferedReader br=new BufferedReader(filereader);
               String s;
               int linecount=0;

               String keyword = keskkond; //keskkond is like Facebook etc..

               try {
                while ((s = br.readLine())!=null){
                      if(s.contains(keyword))
                     System.out.println(s);

                   }
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }                                                                             
               }
   }

这是人们可以输入网络和密码的地方，然后它将其写入文件。

  //Add your password and network and Button actions
  btnLisaParool = new JButton("Add passowrd");
  btnLisaParool.setBackground(new Color(37, 209, 175));
  btnLisaParool.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent e) {




    String parool = String.valueOf(passwordField.getPassword());
    String koht = textField.getText();
    if (koht.isEmpty() && parool.isEmpty()) {
     lblFeedback.setText("You didn't enter anything.");
    } else if(parool.isEmpty()) {
        lblFeedback.setText("Enter password please!.");
    }else if(koht.isEmpty()){
        lblFeedback.setText("Enter network please!");
    }else{
     FileWriter fWriter = null;
     BufferedWriter writer = null;
     try {
      fWriter = new FileWriter("paroolid.txt", true);
      writer = new BufferedWriter(fWriter);
      writer.write("Teie " + koht + " -i parool oli: " + parool);
      writer.newLine();
      writer.close();
      lblFeedback.setText("Teie " + koht + " parool, mis koosnes " + parool.length() + " tähest, on salvestatud.");

     } catch (Exception e1) {
         lblFeedback.setText("Error: " + "Couldn't find file");
     }

    }
    passwordField.setText("");
    textField.setText("");
   }

Answer 1

首先，不要在 EDT 上执行长时间运行的操作(例如读/写文件)。其次，确保释放所有使用的资源以防止内存泄漏。要回答您的问题，您可以将您正在搜索的 String 和正在搜索的字符串修改为小写或大写。

这是一个例子:

try(BufferedReader br = new BufferedReader(new FileReader("paroolid.txt"))){
    for(String line; (line = br.readLine()) != null;){
        if(line.toLowerCase().contains(toSearchFor.toLowerCase())){
            System.out.println(line);
        }
    }
}catch(Exception e){
    e.printStackTrace();
}