read header entries of any file from GraphHopper without dependencies

ReadGHFile.java

import java.io.RandomAccessFile;

class ReadGHFile {
 public static void main(String[] args) throws Exception {
   String name = args[0];
   RandomAccessFile raFile = new RandomAccessFile(name, "r");
   
   raFile.seek(0);
   if (raFile.length() == 0) throw new IllegalArgumentException("empty file " + name);

   String versionHint = raFile.readUTF();
   if (!"GH".equals(versionHint)) throw new IllegalArgumentException("Not a GraphHopper file! Expected 'GH' as file marker but was " + versionHint);

   System.out.println("bytes: " + raFile.readLong());
   System.out.println("seg size:" + raFile.readInt());
   for (int i = 0; i < 20; i++) {
      System.out.println(i+"\t: " + raFile.readInt());
   }
 }
}