public void toDot(String file) {
try {
BufferedWriter out = new BufferedWriter(new FileWriter(file));
out.write("digraph Stree {\n");
StringBuffer str = new StringBuffer();
toDot(str);
out.write(str.toString());
out.write("}\n");
out.close();
} catch (IOException e) {
System.err.println("ERROR: build dot");
}
}
public void toDot(StringBuffer str) {
str.append("e_" + id + " [");
str.append("shape=\"ellipse\", label=\"" + toString());
str.append("\"];\n");
}