[SOLVED] [newbie] AbstractButton.setText() not setting text within JButton

[jon80]

I have this calculator program and it does not seem to clear the display text. So when I select the '=' the previous text does not clear.

:confused:

CalculatorPanel.java
package homenetwork.bkr.training;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

@SuppressWarnings("serial")
public class CalculatorPanel extends JPanel {
	public CalculatorPanel()
	{
		setLayout(new BorderLayout());
		
		result =0;
		lastCommand = "=";
		start=true;
		
		//add the display
		display = new JButton("0");
		display.setEnabled(false);
		add(display, BorderLayout.NORTH);
		
		ActionListener insert = new InsertAction();
		@SuppressWarnings("unused")
		ActionListener command = new CommandAction();
		
		//add the buttons in a 4 X 4 grid
		panel = new JPanel();
		panel.setLayout(new GridLayout(4,4));
		
		addButton("7", insert);
		addButton("8", insert);
		addButton("9", insert);
		addButton("/", insert);
		
		addButton("4", insert);
		addButton("5", insert);
		addButton("6", insert);
		addButton("*", insert);
		
		addButton("1", insert);
		addButton("2", insert);
		addButton("3", insert);
		addButton("-", insert);
		
		addButton("0", insert);
		addButton(".", insert);
		addButton("=", insert);
		addButton("+", insert);
		
		add(panel,BorderLayout.CENTER);
	}
	
		/**
		 * Adds a button to the center panel.
		 * @param label: the button label
		 * @param listener: the button listener
		 */
		private void addButton(String label, ActionListener listener)
		{
			JButton button = new JButton(label);
			button.addActionListener(listener);
			panel.add(button);
		}
		
		/**
		 * This action inserts the button action string to the end of the display text.
		 */
		private class InsertAction implements ActionListener
		{
			public void actionPerformed (ActionEvent event)
			{
				String input = event.getActionCommand();
				if (start)
				{
					display.setText("");
					start = false;
				}
				display.setText(display.getText() + input);
			}
		}
		
		/**
		 * This action executes the command that the button action string denotes.
		 */
		private class CommandAction implements ActionListener
		{
			public void actionPerformed (ActionEvent event) {
				String command = event.getActionCommand();
				if (start)
				{
					if (command.equals("-"))
					{
						display.setText(command);
						start=false;
					}
					else lastCommand = command;
				}
				else 
				{
					calculate(Double.parseDouble(display.getText()));
					lastCommand = command;
					start = true;
				}
			}
		}
		
		/**
		 * Carries out the pending calculation
		 */
		public void calculate(double x)
		{
			if (lastCommand.equals("+")) result += x;
			else if (lastCommand.equals("-")) result -= x;
			else if (lastCommand.equals("*")) result *= x;
			else if (lastCommand.equals("/")) result /= x;
			else if (lastCommand.equals("=")) result = x;
			[B]display.setText("" + result);[/B]
			
		}
		
		[B]private JButton display;[/B]
		private JPanel panel;
		private double result;
		private String lastCommand;
		private boolean start;
}

CalculatorFrame.java
package homenetwork.bkr.training;

import javax.swing.*;

@SuppressWarnings("serial")
public class CalculatorFrame extends JFrame {
	public CalculatorFrame()
	{
		setTitle("Calculator");
		CalculatorPanel panel = new CalculatorPanel();
		add(panel);
		pack();
	}
}


CalculatorTest.java
package homenetwork.bkr.training;

import java.awt.EventQueue;

import javax.swing.JFrame;

public class CalculatorTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable()
			{
				public void run()
				{
					CalculatorFrame frame = new CalculatorFrame();
					frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
					frame.setVisible(true);
				}
			});
	}

}

NOTE: It would be nice to have line numbers for code snippets.

[OrangeDog]

Probably the same old story - you need to call repaint() after changing the GUI.

NOTE: It would be nice to have line numbers for code snippets.

Then put line numbers in your code.

[Singing Boyo]

Hmm... line numbers would be nice in code snippets...

@OrangeDog Probably wouldn't be very good for the code to have line numbers entered into it. I think he means line numbers added to it whenever you post.

@OP Post a thread in the suggestions forum, see what happens

[Fubarable]

repaint() may not help here as you're calling setText on a JTextField, and Swing should update that automatically without a repaint. Rather, I wonder if the problem is that you're giving all of your buttons InsertAction ActionListeners including the non-numeric buttons, the ones that perhaps would work better if assigned CommandAction listeners?