String[] newFileList = new File("D:\\IRAM\\Tek\\OPMET\\SIGMET\\").list();

StringBuffer Strings = new StringBuffer(string);
              Strings.delete(4, 100);

 DefaultMutableTreeNode selectedNode = (DefaultMutableTreeNode) jTree1.getLastSelectedPathComponent();


        if (selectedNode == null) {
            return;
        }
        if (!selectedNode.isLeaf()) {
            return;
        }
        try {


            FileReader file_reader = new FileReader(Path_data + selectedNode);
            char buffer[] = new char[4096];
            int len;

            while ((len = file_reader.read(buffer)) != -1) {
                String s = new String(buffer, 0, len);
                jTextPane1.setText(s);
            }
        } catch (IOException e1) {
        }

public Sigmet() {
        initComponents();

        rootNode = new DefaultMutableTreeNode("SIGMET");
        model = new DefaultTreeModel(rootNode);
        jTree1.setModel(model);
        jTree1.setEditable(true);
        jTree1.setShowsRootHandles(true);
        jTree1.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);

        nodeMainFIR = new DefaultMutableTreeNode(Name_main);
        rootNode.add(nodeMainFIR);

        nodeAuxFIRs = new DefaultMutableTreeNode("Смежные");
        rootNode.add(nodeAuxFIRs);
        nodeAuxFIRList = new DefaultMutableTreeNode[RPI.size()];
        
        
        for (int i = 0; i < RPI.size(); ++i) {
            nodeAuxFIRList[i] = new DefaultMutableTreeNode(RPI.get(i));
            nodeAuxFIRs.add(nodeAuxFIRList[i]);


        }
        updateTree();
        repaint();

private void updateTree() {
        boolean isCommon;
        String[] newFileList = new File("D:\\IRAM\\Tek\\OPMET\\SIGMET\\").list();
        // Удаление старых
        for (int oldFileIndex = 0; oldFileIndex < totalFileList.length; ++oldFileIndex) {
            isCommon = false;
            for (int newFileIndex = 0; newFileIndex < newFileList.length; ++newFileIndex) {
                if (totalFileList[oldFileIndex].equals(newFileList[newFileIndex])) {
                    isCommon = true;
                    break;
                }
            }
            if (!isCommon) {
                deleteLeafFromTree(totalFileList[oldFileIndex]);
            }
        }
        // Добавление новых
        for (int newFileIndex = 0; newFileIndex < newFileList.length; ++newFileIndex) {
            isCommon = false;
            for (int oldFileIndex = 0; oldFileIndex < totalFileList.length; ++oldFileIndex) {
                if (newFileList[newFileIndex].equals(totalFileList[oldFileIndex])) {
                    isCommon = true;
                    break;
                }
            }
            if (!isCommon) {
                addLeafIntoTree(newFileList[newFileIndex]);

            }
        }
        // Запоминаем новый список
        totalFileList = newFileList;
    }

    public void deleteLeafFromTree(String string) {
        int sumMain = nodeMainFIR.getChildCount(); //Получаем кол-во главных FIR
        for (int i = 0; i < sumMain; ++i) {
            DefaultMutableTreeNode child = (DefaultMutableTreeNode) nodeMainFIR.getChildAt(i);

            if (child.toString().equals(string)) {
                model.removeNodeFromParent(child);
                break;
            }
        }
        for (int i = 0; i < RPI.size(); ++i) {
            int sumAux = nodeAuxFIRList[i].getChildCount();
            for (int j = 0; j < sumAux; ++j) {
                DefaultMutableTreeNode child = (DefaultMutableTreeNode) nodeAuxFIRList[i].getChildAt(j);
                if (child.toString().equals(string)) {
                    model.removeNodeFromParent(child);
                    break;
                }
            }
        }

        model.nodeChanged(nodeMainFIR);

        repaint();

    }

    public void addLeafIntoTree(String string) {
        
        model.insertNodeInto(new DefaultMutableTreeNode(string), nodeMainFIR, nodeMainFIR.getChildCount());
        model.nodeChanged(nodeMainFIR);
        repaint();


        for (int i = 0; i < RPI.size(); ++i) {
            model.insertNodeInto(new DefaultMutableTreeNode(string), nodeAuxFIRList[i], nodeAuxFIRList[i].getChildCount());
            model.nodeChanged(nodeAuxFIRList[i]);
            repaint();
        }


    }