A new kind of Edge: possibilities include dotted lines, colored lines and lines

Question

A new kind of Edge: possibilities include dotted lines, colored lines and lines with arrowheads

A additional enhancement that makes your graph more specialized than the Simple Graph Editor you are given; for example, you might add the ability to set a background (using a grid or set of evenly spaced lines) or you might restrict certain kinds of Edges to connect only certain kinds of Nodes - or you might come up with something completely original. You must clearly document what your enhancement is by naming your main class something other than SimpleGraphEditor - e.g. GraphEditorWithGrid if you chose the very first option.

Explanation / Answer

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

/**
This frame shows the toolbar and the graph.
*/
public class GraphFrame extends JFrame
{
/**
Constructs a graph frame that displays a given graph.
@param graph the graph to display
*/
public GraphFrame(final Graph graph)
{
setSize(FRAME_WIDTH, FRAME_HEIGHT);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

this.graph = graph;

constructFrameComponents();
// set up menus

JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
JMenu fileMenu = new JMenu("File");
menuBar.add(fileMenu);

JMenuItem openItem = new JMenuItem("Open");
openItem.addActionListener(new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
openFile();
}
});
fileMenu.add(openItem);

JMenuItem saveItem = new JMenuItem("Save");
saveItem.addActionListener(new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
saveFile();
}
});
fileMenu.add(saveItem);

JMenuItem exitItem = new JMenuItem("Exit");
exitItem.addActionListener(new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
System.exit(0);
}
});
fileMenu.add(exitItem);

JMenuItem deleteItem = new JMenuItem("Delete");
deleteItem.addActionListener(new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
panel.removeSelected();
}
});

JMenu editMenu = new JMenu("Edit");
editMenu.add(deleteItem);
menuBar.add(editMenu);
}

/**
Constructs the tool bar and graph panel.
*/
private void constructFrameComponents()
{
toolBar = new ToolBar(graph);
panel = new GraphPanel(toolBar, graph);
scrollPane = new JScrollPane(panel);
Container contentPane = getContentPane();
contentPane.add(toolBar, BorderLayout.NORTH);
contentPane.add(scrollPane, BorderLayout.CENTER);
}

/**
Asks the user to open a graph file.
*/
private void openFile()
{
// let user select file

JFileChooser fileChooser = new JFileChooser();
int r = fileChooser.showOpenDialog(this);
if (r == JFileChooser.APPROVE_OPTION)
{
// open the file that the user selected
try
{
File file = fileChooser.getSelectedFile();
ObjectInputStream in = new ObjectInputStream(
new FileInputStream(file));
graph = (Graph) in.readObject();
in.close();
Container contentPane = getContentPane();
contentPane.remove(scrollPane);
contentPane.remove(toolBar);
constructFrameComponents();
validate();
repaint();
}
catch (IOException exception)
{
JOptionPane.showMessageDialog(null,
exception);
}
catch (ClassNotFoundException exception)
{
JOptionPane.showMessageDialog(null,
exception);
}
}
}

/**
Saves the current graph in a file.
*/
private void saveFile()
{
JFileChooser fileChooser = new JFileChooser();
if (fileChooser.showSaveDialog(this)
== JFileChooser.APPROVE_OPTION)
{
try
{
File file = fileChooser.getSelectedFile();
ObjectOutputStream out = new ObjectOutputStream(
new FileOutputStream(file));
out.writeObject(graph);
out.close();
}
catch (IOException exception)
{
JOptionPane.showMessageDialog(null,
exception);
}
}
}

private Graph graph;
private GraphPanel panel;
private JScrollPane scrollPane;
private ToolBar toolBar;

public static final int FRAME_WIDTH = 600;
public static final int FRAME_HEIGHT = 400;
}

---------------------------------------------------------------------------------------------------------------------------------------------------------------

import java.awt.*;
import java.util.*;

public class SimpleGraph extends Graph
{
public Node[] getNodePrototypes()
{
Node[] nodeTypes =
{
new CircleNode(Color.BLACK),
new CircleNode(Color.WHITE)
};
return nodeTypes;
}

public Edge[] getEdgePrototypes()
{
Edge[] edgeTypes =
{
new LineEdge()
};
return edgeTypes;
}
}

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