🌟 Introduction
In the previous AWT blog, we learned how to:
- Create GUI windows 🪟
- Add components like Button, Label, TextField
- Use Layout Managers 🎯
👉 But there was one big missing piece…
❗ How do we take input from the user and actually process it?
This blog solves that problem 💡
🧠 What You Will Learn
- How to read input from
TextField - How to handle button click events
- How to process input (like Even/Odd, Sum, etc.)
- How GUI becomes interactive 🔥
🔄 Event Handling in AWT (Basic Idea)
👉 When a user clicks a button:
- An event is generated ⚡
- We must handle it using ActionListener
🧱 Basic Structure of Event Handling
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
// Code to execute on button click
}
});
🧪 Program 1: Even or Odd Checker
✅ Complete Runnable Program
import java.awt.*;
import java.awt.event.*;
public class EvenOddAWT {
public static void main(String[] args) {
Frame frame = new Frame("Even Odd Checker");
frame.setLayout(new FlowLayout());
Label label = new Label("Enter Number:");
TextField tf = new TextField(10);
Button btn = new Button("Check");
Label result = new Label("");
frame.add(label);
frame.add(tf);
frame.add(btn);
frame.add(result);
btn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
int num = Integer.parseInt(tf.getText());
if (num % 2 == 0) {
result.setText("Even Number ✅");
} else {
result.setText("Odd Number 🔥");
}
} catch (Exception ex) {
result.setText("Invalid Input ❌");
}
}
});
frame.setSize(300, 200);
frame.setVisible(true);
}
}
🔍 Explanation
tf.getText()→ reads input from userInteger.parseInt()→ converts String to intActionListener→ handles button clicksetText()→ displays output
🧪 Program 2: Addition of Two Numbers
✅ Complete Runnable Program
import java.awt.*;
import java.awt.event.*;
public class AdditionAWT {
public static void main(String[] args) {
Frame frame = new Frame("Addition Calculator");
frame.setLayout(new FlowLayout());
TextField tf1 = new TextField(10);
TextField tf2 = new TextField(10);
Button btn = new Button("Add");
Label result = new Label("Result: ");
frame.add(new Label("Number 1:"));
frame.add(tf1);
frame.add(new Label("Number 2:"));
frame.add(tf2);
frame.add(btn);
frame.add(result);
btn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
int n1 = Integer.parseInt(tf1.getText());
int n2 = Integer.parseInt(tf2.getText());
int sum = n1 + n2;
result.setText("Result: " + sum);
} catch (Exception ex) {
result.setText("Invalid Input ❌");
}
}
});
frame.setSize(300, 200);
frame.setVisible(true);
}
}
🧪 Program 3: Factorial Calculator
✅ Complete Runnable Program
import java.awt.*;
import java.awt.event.*;
public class FactorialAWT {
public static void main(String[] args) {
Frame frame = new Frame("Factorial Calculator");
frame.setLayout(new FlowLayout());
TextField tf = new TextField(10);
Button btn = new Button("Find Factorial");
Label result = new Label("");
frame.add(new Label("Enter Number:"));
frame.add(tf);
frame.add(btn);
frame.add(result);
btn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
int num = Integer.parseInt(tf.getText());
int fact = 1;
for (int i = 1; i <= num; i++) {
fact *= i;
}
result.setText("Factorial: " + fact);
} catch (Exception ex) {
result.setText("Invalid Input ❌");
}
}
});
frame.setSize(300, 200);
frame.setVisible(true);
}
}
🧪 Program 4: Reverse a Number
✅ Complete Runnable Program
import java.awt.*;
import java.awt.event.*;
public class ReverseNumberAWT {
public static void main(String[] args) {
Frame frame = new Frame("Reverse Number");
frame.setLayout(new FlowLayout());
TextField tf = new TextField(10);
Button btn = new Button("Reverse");
Label result = new Label("");
frame.add(new Label("Enter Number:"));
frame.add(tf);
frame.add(btn);
frame.add(result);
btn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
int num = Integer.parseInt(tf.getText());
int rev = 0;
while (num != 0) {
int digit = num % 10;
rev = rev * 10 + digit;
num /= 10;
}
result.setText("Reverse: " + rev);
} catch (Exception ex) {
result.setText("Invalid Input ❌");
}
}
});
frame.setSize(300, 200);
frame.setVisible(true);
}
}
How to make the program close by clicking on the close button of the frame:-
import java.awt.*;
import java.awt.event.*;
public class CloseWindowDemo {
public static void main(String[] args) {
Frame frame = new Frame("Close Example");
frame.setSize(300, 200);
// Handling window closing event
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0); // Terminates program
}
});
frame.setVisible(true);
}
}⚠️ Common Mistakes Students Make
❌ Forgetting getText()
👉 You cannot directly use TextField value
❌ Not converting String to int
int num = tf.getText(); // ❌ WRONG
❌ Not handling invalid input
👉 Program crashes if user enters text
❌ Forgetting to add ActionListener
👉 Button will not work
🤯 Common Confusions
🤔 Why input is String?
👉 Because GUI components deal with text
🤔 Why use ActionListener?
👉 To respond to user actions (clicks)
💼 Interview Questions
❓ How to read input from TextField?
👉 Using getText()
❓ How to handle button click?
👉 Using ActionListener
❓ Why convert String to int?
👉 Because TextField returns String
🎯 Key Takeaways
✔️ GUI input is always String
✔️ Use getText() to read input
✔️ Use parseInt() to convert
✔️ Use ActionListener for interaction
🏁 Conclusion
Now your GUI is no longer static — it is interactive 🎯
You learned:
- ✔️ How to take input from user
- ✔️ How to process data
- ✔️ How to handle events
- ✔️ Building real AWT applications
💡 Final Thought
👉 This is the bridge between basic GUI and real applications 🚀
🔥 One-Line Summary
👉 “AWT becomes powerful when user input and event handling are combined.”
💻 Happy Coding! 😄
Next step: Event Delegation Model (deep dive) & Swing 🔥
