I've written two classes, one that extends JPanel, and the other which contains only the main method. If I add these two classes to a project in Eclipse, and then run the project as a Java Application, the JPanel is displayed. When I invoke java from bash, it behaves exactly the same as in the Eclipse IDE. However, when I invoke java using my ant build file, It never displays the JPanel.

			

			// class containing the main method
			

			package myPkg;
			

			

			import javax.swing.JFrame;
			

			import javax.swing.JPanel;
			

			public class myApp {
			

			

			public static void main(String[] args) {
			

			

			JFrame frame = new JFrame("My Frame!");
			

			frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
			

			myPanel panel = new myPanel();
			

			frame.getContentPane().add(panel);
			

			frame.pack();
			

			frame.show();
			

			System.out.println("!");
			

			}
			

			}
			

		

			

			// class containing my JPanel
			

			package myPkg;
			

			

			import java.awt.Color;
			

			import java.awt.Dimension;
			

			import java.awt.Graphics;
			

			import javax.swing.JPanel;
			

			

			public class myPanel extends JPanel {
			

			

			public myPanel() {
			

			setPreferredSize(new Dimension(400, 400));
			

			setBackground(Color.white);
			

			setVisible(true);
			

			}
			

			public void paintComponent(Graphics page)
			

			

			{
			

			

			super.paintComponent(page);
			

			

			}
			

			}