Question

Java GUI Help!

Hi, I have a Java GUI exercise that I need to complete and was wondering if I could have a little bit of help... you can see it below.

Create a simple graphical application that will enable a user to perform push, pop and peek operations on a stack and display the resulting stack (using toString) in a text area.

Any help would be much appreciated! Thank you.

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

Note: This program uses Java’s built in Stack class. If you are looking for any custom implementation of the stack, I can provide that, just drop a comment.

// StackGUI.java

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.util.Stack;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPanel;

import javax.swing.JTextArea;

import javax.swing.JTextField;

public class StackGUI extends JFrame implements ActionListener {

      // declaring UI components and the Stack

      private JTextField input;

      private JButton push, pop, peek;

      private JTextArea result;

      private Stack<String> stk;

      public StackGUI() {

            // initializing stack

            stk = new Stack<String>();

            // using grid layout of 1 column as main layout

            setLayout(new GridLayout(0, 1));

            // initializing the GUI

            // creating a panel for input label and textfield

            JPanel inpPanel = new JPanel();

            inpPanel.add(new JLabel("Input: "));

            input = new JTextField(10);

            inpPanel.add(input);

            // creating a panel for buttons

            JPanel buttonsPanel = new JPanel();

            push = new JButton("PUSH");

            pop = new JButton("POP");

            peek = new JButton("PEEK");

            buttonsPanel.add(push);

            buttonsPanel.add(pop);

            buttonsPanel.add(peek);

            // adding action listener to the buttons

            push.addActionListener(this);

            pop.addActionListener(this);

            peek.addActionListener(this);

            // initializing text area, making it not editable, setting current value

            // of stack as its text

            result = new JTextArea();

            result.setEditable(false);

            result.setText("Stack: " + stk);

            // adding all to main frame.

            add(inpPanel);

            add(buttonsPanel);

            add(result);

            setDefaultCloseOperation(EXIT_ON_CLOSE);

            setSize(400, 200);

            setVisible(true); // making window visible

      }

      public static void main(String[] args) {

            new StackGUI();

      }

      @Override

      public void actionPerformed(ActionEvent e) {

            // resetting text area

            result.setText("");

            // finding the source of action

            if (e.getSource().equals(push)) {

                  // getting text from input, pushing to stack if it is not empty

                  String value = input.getText();

                  if (value.length() > 0) {

                        stk.push(value);

                        result.setText("Pushed value: " + value);

                        // resetting input

                        input.setText("");

                  }

            } else if (e.getSource().equals(pop)) {

                  // popping a value from stack and displaying if not empty

                  if (stk.isEmpty()) {

                        result.setText("Error! Stack is empty: ");

                  } else {

                        result.setText("Popped value: " + stk.pop());

                  }

            } else {

                  // peeking a value from stack and displaying if not empty

                  if (stk.isEmpty()) {

                        result.setText("Error! Stack is empty: ");

                  } else {

                        result.setText("Value on top: " + stk.peek());

                  }

            }

            // finally appending the contents of stack to result text area

            result.append("\nStack: " + stk);

      }

}

/*OUTPUT*/

Input: Felicity PUSH POP PEEK Pushed value: John Stack: [Oliver, John]

Input: PUSHPOP PEEK alue on top: Felicity Stack: [Oliver, John, Felicity

Input: PUSH POP PEEK Po Stack: [Oliver, John]