autocomplete in text file

[Markus1]

i am not so good in java.
I have a running code for search in text with a txt. file (from user bluefox815).

But I need a solution with autocomplete for for search in text with a txt. file.

Can you help me please.

Here is the code:
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import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;

/*
* this program searches for a string in a text file and
* says which line it found the string on
*/

public class SearchText implements ActionListener {

private String filename = "test_file.txt";

private JFrame frame;
private JTextField searchField;
private JButton searchButton;
private JLabel lineLabel;
private String searchFor;
private BufferedReader in;

public SearchText() {
frame = new JFrame("SearchText");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
searchField = new JTextField(80);
searchButton = new JButton("Search");
// this is used later in our actionPerformed method
searchButton.setActionCommand("search");
// this sets the action listener for searchButton, which is the current class
// because this class implements ActionListener
searchButton.addActionListener(this);
lineLabel = new JLabel("nach dem Fachbegriff suchen");
}

public void createGUI() {
JPanel topPanel = new JPanel();
topPanel.setLayout(new BoxLayout(topPanel, BoxLayout.X_AXIS));
JPanel bottomPanel = new JPanel();
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));
topPanel.add(searchField);
topPanel.add(searchButton);
bottomPanel.add(lineLabel);
mainPanel.add(topPanel);
mainPanel.add(bottomPanel);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setVisible(true);
}

public void actionPerformed(ActionEvent e) {
// now we get the action command and if it is search, then it is the button
if ("search".equals(e.getActionCommand())) {
searchFor = searchField.getText();
searchTheText();
}
}

private void searchTheText() {
// I initialize the buffered reader here so that every time the user searches
// then the reader will start at the beginning, instead of where it left off last time
try {
in = new BufferedReader(new FileReader(new File(filename)));
} catch (IOException e) {
}
String lineContent = null;
int currentLine = 0;
// this will be set to true if the string was found
boolean foundString = false;
while (true) {
currentLine++;
// get a line of text from the file
try {
lineContent = in.readLine();
} catch (IOException e) {
break;
}
// checks to see if the file ended (in.readLine() returns null if the end is reached)
if (lineContent == null) {
break;
}
if (lineContent.indexOf(searchFor) == -1) {
continue;
} else {
lineLabel.setText(String.valueOf(lineContent));
foundString = true;
break;
}
}
if (!foundString)
lineLabel.setText("Es kann kein Fachbegriff gefunden werden.");
try {
in.close();
} catch (IOException ioe) {
}
}

public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new SearchText().createGUI();
}
});
}

}