package com.example;

import java.awt.*;         // Using AWT's containers and components
import java.awt.event.*;   // Using AWT's event classes and listener interfaces

// An AWT GUI program inherits the top-level container java.awt.Frame
public class AWTCounter extends Frame implements ActionListener {
    private Label lblCount;     // Declare component Label
    private TextField tfCount;  // Declare component TextField
    private Button btnCount;    // Declare component Button
    private int count = 0;      // counter's value

    // Constructor to setup UI components and event handlers
    public AWTCounter () {
        setLayout(new FlowLayout());
        // "super" Frame sets layout to FlowLayout, which arranges
        //  Components from left-to-right, then top-to-bottom.

        lblCount = new Label("Counter"); // Construct component Label
        add(lblCount);                   // "super" Frame adds Label

        tfCount = new TextField(count + "", 10); // Construct component TextField
        tfCount.setEditable(false);       // read-only
        add(tfCount);                     // "super" Frame adds TextField

        btnCount = new Button("Count");   // Construct component Button
        add(btnCount);                    // "super" Frame adds Button
        btnCount.addActionListener(this);
        // btnCount is the source object that fires ActionEvent when clicked.
        // The source add "this" instance as an ActionEvent listener, which provides
        //  an ActionEvent handler called actionPerformed().
        // Clicking btnCount invokes actionPerformed().

        setSize(250, 100);       // "super" Frame sets initial size
        setTitle("AWT Counter"); // "super" Frame sets title
        setVisible(true);        // show "super" Frame
    }

    // ActionEvent handler - Called back when the button is clicked.
    @Override
    public void actionPerformed(ActionEvent evt) {
        ++count;                     // Incrase the counter value
        tfCount.setText(count + ""); // Display on the TextField
        // setText() takes a String
    }

    // The entry main() method
    public static void main(String[] args) {
        // Invoke the constructor by allocating an anonymous instance
        new AWTCounter();
    }
}