==== Here is the minimized test demonstrating the bug ====
import java.io.*;
public class java_io_RandomAccessFile_writeUTF {
  public static void main( String argv[] ) {
    RandomAccessFile f;
    String s="\uffff";
    for (int i=0; i<16; i++) 
      s+=s;
    System.out.println("String length= "+s.length());

    try {
      f=new RandomAccessFile("new_file","rw");

      try {
        f.writeUTF(s);
      }
      catch (Error e) {
        System.out.println(e);
      }
      System.out.println("File length now: "+f.length());

    }
    catch (IOException e) {
      System.out.println(e);
    }
  }
 
}
==== Here is the output of the test ====
String length= 65536
File length now: 196610