Beginning Swing programming problem

Question

My classmates and I are trying to write a simple Swing program with a single button and a text field that contains the number of times the button has been pressed since the program started. The problem is that in the ActionPerformed method, any changes to the text field ends up with multiple event errors. It will print the count fine to the command prompt, but not the GUI. Any insight would be greatly appreciated.
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
class CounterGUI extends JFrame implements ActionListener
     public int count = 0;
     Container contents = getContentPane();
     JTextField counter;
     final String temp = "Total times pressed: ";
     public CounterGUI()
          final int width = 300;
          final int height = 300;
          setSize(width, height);
          JTextField counter = new JTextField(temp + count);
          counter.setEditable(false);
          JButton clicker = new JButton("Click me!");
          clicker.addActionListener(this);
          clicker.setActionCommand("Click");
          contents.add(counter, "Center");
          contents.add(clicker, "South");
     public void actionPerformed(ActionEvent e)
          String command = e.getActionCommand();
          if(command == "Click")
               count++;
               counter.setText(temp + count);     
               System.out.println(count);
     public static void main(String[] args)
     JFrame f = new CounterGUI();
     f.addWindowListener(new WindowCloser());
          f.setVisible(true);

Answer 1

Hi Guys,
The line JTextField counter = new JTextField(temp + count); is declared in the constructor, this means that the field counter is not visible to other methods and you'll get a null pointer exception (NPE) when you try to access the class field counter
Change to counter = new JTextField(temp + count); Now if you were catching and displaying exceptions you'd notice that this was happening.
Dave