MessManagementAWT.java

import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;

class Student {
    String id;
    String name;
    int meals;
    double bill;

    static final double COST_PER_MEAL = 50.0;

    Student(String id, String name) {
        this.id = id;
        this.name = name;
        this.meals = 0;
        this.bill = 0.0;
    }

    void addMeal() {
        meals++;
        bill += COST_PER_MEAL;
    }

    public String toString() {
        return id + " | " + name + " | Meals: " + meals + " | Bill: ₹" + bill;
    }
}

public class MessManagementAWT extends Frame implements ActionListener {
    TextField idField, nameField;
    TextArea outputArea;
    Button addBtn, mealBtn, viewBtn, clearBtn;
    ArrayList<Student> students = new ArrayList<>();

    public MessManagementAWT() {
        setTitle("Mess Management System");
        setSize(500, 500);
        setLayout(null);
        setBackground(new Color(240, 248, 255));

        Label idLabel = new Label("Student ID:");
        idLabel.setBounds(50, 50, 80, 25);
        add(idLabel);

        idField = new TextField();
        idField.setBounds(140, 50, 120, 25);
        add(idField);

        Label nameLabel = new Label("Name:");
        nameLabel.setBounds(50, 90, 80, 25);
        add(nameLabel);

        nameField = new TextField();
        nameField.setBounds(140, 90, 200, 25);
        add(nameField);

        addBtn = new Button("Register");
        addBtn.setBounds(50, 130, 80, 30);
        addBtn.addActionListener(this);
        add(addBtn);

        mealBtn = new Button("Mark Meal");
        mealBtn.setBounds(140, 130, 90, 30);
        mealBtn.addActionListener(this);
        add(mealBtn);

        viewBtn = new Button("View All");
        viewBtn.setBounds(240, 130, 80, 30);
        viewBtn.addActionListener(this);
        add(viewBtn);

        clearBtn = new Button("Clear");
        clearBtn.setBounds(330, 130, 60, 30);
        clearBtn.addActionListener(this);
        add(clearBtn);

        outputArea = new TextArea();
        outputArea.setEditable(false);
        outputArea.setBounds(50, 180, 390, 250);
        add(outputArea);

        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                dispose();
            }
        });

        setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        String id = idField.getText().trim();
        String name = nameField.getText().trim();

        if (e.getSource() == addBtn) {
            if (id.isEmpty() || name.isEmpty()) {
                showMessage("Enter both ID and Name!");
                return;
            }
            students.add(new Student(id, name));
            showMessage("Student registered.");
            clearFields();

        } else if (e.getSource() == mealBtn) {
            Student student = findStudent(id);
            if (student == null) {
                showMessage("Student not found.");
            } else {
                student.addMeal();
                showMessage("Meal marked for " + student.name);
            }

        } else if (e.getSource() == viewBtn) {
            if (students.isEmpty()) {
                showMessage("No students found.");
            } else {
                StringBuilder sb = new StringBuilder("---- Students ----\n");
                for (Student s : students) {
                    sb.append(s).append("\n");
                }
                outputArea.setText(sb.toString());
            }

        } else if (e.getSource() == clearBtn) {
            clearFields();
            outputArea.setText("");
        }
    }

    void showMessage(String msg) {
        outputArea.setText(msg);
    }

    void clearFields() {
        idField.setText("");
        nameField.setText("");
    }

    Student findStudent(String id) {
        for (Student s : students) {
            if (s.id.equalsIgnoreCase(id)) return s;
        }
        return null;
    }

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