Get value from JTextCompnent and convert it to upper case : JTextComponent « Swing JFC « Java

Get value from JTextCompnent and convert it to upper case


import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;

public class Main implements ActionListener {
  JTextField jtf = new JTextField(10);

  JButton jbtnGetTextUpper = new JButton("Get Text In Uppercase");

  Main() {
    JFrame jfrm = new JFrame("Demonstrate a Text Field");
    jfrm.setLayout(new FlowLayout());
    jfrm.setSize(240, 140);


    jtf.addCaretListener(new CaretListener() {
      public void caretUpdate(CaretEvent ce) {
        System.out.println("Text in real time: " + jtf.getText());


  public void actionPerformed(ActionEvent ae) {
    if (ae.getActionCommand().equals("TF")) {
      System.out.println("ENTER key pressed: " + jtf.getText());
    } else {
      String str = jtf.getText().toUpperCase();
      System.out.println("Button pressed: " + str);

  public static void main(String args[]) {
    new Main();


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14.Sharing a Document Between JTextComponents
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18.Using the Selection of a JTextComponent
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22.Remove Highlighting in a JTextComponent
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