NullPointerException in working with JButtons - io

Question

public class Node extends JButton {
private Node rightConnection ;
private Node downConnection ;
private Node rightNode ,downNode, leftNode ,upNode;
private ArrayList<String> buttonImages = new ArrayList<String>();
public static void connectNodes(ArrayList<Node> nodes) {
for (int i = 0; i < nodes.size(); i++) {
nodes.get(i).setRightNode((nodes.get(i).getLocation().x / 150 < Integer.parseInt(SetMap.getMapSize()) - 1) ? nodes.get(i + 1) : null);
nodes.get(i).setDownNode((nodes.get(i).getLocation().y / 150 < Integer.parseInt(SetMap.getMapSize()) - 1) ? nodes.get(i + Integer.parseInt(SetMap.getMapSize())) : null);
nodes.get(i).setLeftNode((nodes.get(i).getLocation().x / 150 > 0) ? nodes.get(i - 1) : null);
nodes.get(i).setUpNode((nodes.get(i).getLocation().y / 150 > 0) ? nodes.get(i - Integer.parseInt(SetMap.getMapSize())) : null);
}
}
public class SetContent {
private JPanel contentPanel;
private int imgNum;
public SetContent() {
contentPanel = new JPanel(null);
contentPanel.setLocation(1166, 0);
contentPanel.setSize(200, 768);
makeOptionNodes();
}
private void makeOptionNodes() {
MouseListener mouseListener = new DragMouseAdapter();
for (int row = 0; row < 13; row++) {
for (int col = 0; col < 2; col++) {
Node button = new Node();
button.setSize(100, 50);
button.setLocation(col * 100, row * 50);
ImageIcon img = new ImageIcon("src/com/company/" + this.imgNum++ + ".png");
button.setIcon(new ImageIcon(String.valueOf(img)));
// to remote the spacing between the image and button's borders
//button.setMargin(new Insets(0, 0, 0, 0));
// to add a different background
//button.setBackground( ... );
button.setTransferHandler(new TransferHandler("icon"));
button.addMouseListener(mouseListener);
contentPanel.add(button);
}
}
}
}
public class DragMouseAdapter extends MouseAdapter{
String name= new String();
public void mousePressed(MouseEvent e) {
JComponent c = (JComponent) e.getSource();
TransferHandler handler = c.getTransferHandler();
handler.exportAsDrag(c, e, TransferHandler.COPY);
name = handler.getDragImage().toString();// here is another nullpointerException
for(int i = 0 ; i< Integer.parseInt(SetMap.getMapSize()) ; i++) {
if (c.getName().equals(String.valueOf(i))) {
((Node) c).getButtonImages().add(name);
}
}
}
}
public class SetMap {
private static String mapSize;
private JPanel nodesPanel;
private ArrayList<Node> nodes;
public SetMap() {
nodes = new ArrayList<Node>();
for (Node node : nodes) {
node = new Node();
}
nodesPanel = new JPanel(null);
nodesPanel.setLocation(0, 0);
nodesPanel.setSize(1166, 768);
this.mapSize = JOptionPane.showInputDialog(null, "enter map size:");
makeMapNodes();
Node.connectNodes(this.nodes);
makeConnections();
}
private void makeMapNodes() {
for (int row = 0; row < Integer.parseInt(this.mapSize); row++) {
for (int col = 0; col < Integer.parseInt(this.mapSize); col++) {
final Node button = new Node();
button.setRightNode(null);
button.setDownNode(null);
button.setLeftNode(null);
button.setUpNode(null);
button.setRightConnection(null);
button.setDownConnection(null);
button.setTransferHandler(new TransferHandler("icon"));
button.setSize(100, 100);
button.setLocation(col * 150, row * 150);
this.nodes.add(button);
nodesPanel.add(button);
Node.setNodeName(this.nodes, this.nodes.indexOf(button));
button.addActionListener(new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
int index = nodes.indexOf(button);
nodes.remove(button);
Node.setNodeName(nodes, index);
button.invalidate();
button.setVisible(false);
if (button.getLocation().x / 150 < Integer.parseInt(SetMap.getMapSize()) - 1) {
button.getRightConnection().invalidate();
button.getRightConnection().setVisible(false);
}
if (button.getLocation().y / 150 < Integer.parseInt(SetMap.getMapSize()) - 1) {
button.getDownConnection().invalidate();
button.getDownConnection().setVisible(false);
}
if (button.getLocation().x / 150 > 0) {
button.getLeftNode().getRightConnection().invalidate();
button.getLeftNode().getRightConnection().setVisible(false);
}
if (button.getLocation().y / 150 > 0) {
button.getUpNode().getDownConnection().invalidate();
button.getUpNode().getDownConnection().setVisible(false);
}
}
});
}
}
}
private void makeConnections() {
for (Node button : this.nodes){
final Node rightConnection = new Node();
final Node downConnection = new Node();
rightConnection.setSize(50, 35);
downConnection.setSize(35, 50);
rightConnection.setLocation(button.getLocation().x + 100, button.getLocation().y + 35);
downConnection.setLocation(button.getLocation().x + 35, button.getLocation().y + 100);
button.setRightConnection(rightConnection);
button.setDownConnection(downConnection);
ImageIcon imgH = new ImageIcon("src/com/company/horizontal.png");
rightConnection.setIcon(new ImageIcon(String.valueOf(imgH)));
ImageIcon imgV = new ImageIcon("src/com/company/vertical.png");
downConnection.setContentAreaFilled(false);
downConnection.setIcon(new ImageIcon(String.valueOf(imgV)));
if(button.getLocation().x / 150 != Integer.parseInt(this.mapSize)-1) {
nodesPanel.add(rightConnection);
}
if(button.getLocation().y / 150 != Integer.parseInt(this.mapSize)-1) {
nodesPanel.add(downConnection);
}
rightConnection.addActionListener(new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
rightConnection.invalidate();
rightConnection.setVisible(false);
}
});
downConnection.addActionListener(new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
downConnection.invalidate();
downConnection.setVisible(false);
}
});
}
}
}
public class File {
public static void writeInFile(ArrayList<Node> nodes) {
try {
FileWriter fileWriter = new FileWriter("G:\\file.txt");
BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
bufferedWriter.write("[" + SetMap.getMapSize() + "]" + "[" + SetMap.getMapSize() + "]");
bufferedWriter.newLine();
Iterator itr = nodes.iterator();
while (itr.hasNext()) {
Node node = (Node) itr.next();
if (node != null) {
bufferedWriter.write(node.getText());
bufferedWriter.newLine();
bufferedWriter.write("R" + ((node.getRightConnection() != null) ? node.getRightNode().getText() : null) + " D" + ((node.getDownConnection() != null) ? node.getDownNode().getText() : null) + " L" + ((node.getLeftNode().getRightConnection() != null) ? node.getLeftNode().getText() : null) + " U" + ((node.getUpNode().getDownConnection() != null) ? node.getUpNode().getText() : null));//here is the NullPOinterException
bufferedWriter.newLine();
bufferedWriter.write("image");
bufferedWriter.newLine();
Iterator it = node.getButtonImages().iterator();
while (it.hasNext()){
String images = (String) it.next();
bufferedWriter.write(" " + images);
}
}
}
bufferedWriter.close();
fileWriter.close();
} catch (IOException e) {
System.out.println(e);
}
}
}
public class Main {
public static void main(String[] args) {
JFrame mainFrame = new JFrame();
mainFrame.setExtendedState(JFrame.MAXIMIZED_BOTH);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setLayout(null);
final SetMap map = new SetMap();
SetContent options = new SetContent();
mainFrame.add(map.getNodesPanel());
mainFrame.add(options.getContentPanel());
JButton saveButton = new JButton("save");
saveButton.setSize(100, 25);
saveButton.setLocation(1050, 10);
saveButton.addActionListener(new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
File.writeInFile(map.getNodes());
}
});
map.getNodesPanel().add(saveButton);
mainFrame.setVisible(true);
JOptionPane.showMessageDialog(null, "choose nodes and connections you want to remove");
}
}
I'm trying to write the changes that are made on some nodes I added in mapPanel but in the File class the line (which is commented), I get NullPointerException and also for another line in class DragMouseAdapter I get this exception again.
I've omitted some unimportant part of code. I know it's a lot to check code but I would be thankful for any simple help in this case cause I'm a real noob in programming.