DELEGATION MODEL

18. Java Program to Display Several Dots on the Screen Continuously

            import java.awt.*;
            import java.awt.event.*;
            
            public class NumericTextFieldApp extends Frame {
            
                private TextField numberField;
            
                public NumericTextFieldApp() {
                    // Set up the frame
                    setTitle("Numeric Text Field Validation");
                    setSize(300, 150);
                    setLayout(new FlowLayout());
            
                    // Create a TextField
                    numberField = new TextField(20);
                    
                    // Add KeyListener to the TextField
                    numberField.addKeyListener(new KeyAdapter() {
                        
                        public void keyTyped(KeyEvent e) {
                            char c = e.getKeyChar();
                            // Check if the input is not a digit and is not a control character
                            if (!Character.isDigit(c) && c != KeyEvent.VK_BACK_SPACE && c != KeyEvent.VK_DELETE) {
                                e.consume(); // Consume the event to prevent the character from being typed
                            }
                        }
                    });
            
                    // Add components to the frame
                    add(new Label("Enter numbers only:"));
                    add(numberField);
            
                    // Set up close operation
                    addWindowListener(new WindowAdapter() {
                        
                        public void windowClosing(WindowEvent windowEvent) {
                            System.exit(0);
                        }
                    });
                }
            
                public static void main(String[] args) {
                    // Create and show the frame
                    NumericTextFieldApp app = new NumericTextFieldApp();
                    app.setVisible(true);
                }
            }
        

OUTPUT