loadjava seems work but the query doesn't work on oracle sql developer

Question

I am trying to load a java class to oracle as a function. In the server I managed to use loadjava as below:

C:\Users\n12017>loadjava -user USER1/passw E:\JAVA_repository\SOOSProjects\Mehmet_java_2db_trial\classes\mehmet_java_2db_trial\kondrakk.class

And in the oracle db side:

create or replace function ngram_kondrakk(src in varchar2, trg in varchar2)
  return float
as language java
  name 'mehmet_java_2db_trial/kondrakk.getDistance(java.lang.string, java.lang.string) return java.lang.float';
/

However, when I apply the query as below, I got error. (As a result of the query I am expecting a similarity score of 1 since two identical strings are compared)

select ngram_kondrakk('mehmet','mehmet') from dual;

Here is the error:

ORA-29532: Java call terminated by uncaught Java exception: System error : java/lang/UnsupportedClassVersionError
29532. 00000 -  "Java call terminated by uncaught Java exception: %s"
*Cause:    A Java exception or error was signaled and could not be
           resolved by the Java code.
*Action:   Modify Java code, if this behavior is not intended.

Finally, here is the code that I am trying to use:

package mehmet_java_2db_trial;

public class kondrakk {

public static float getDistance(String source, String target) {
  final int sl = source.length();
  final int tl = target.length();

  if (sl == 0 || tl == 0) {
    if (sl == tl) {
      return 1;
    }
    else {
      return 0;
    }
  }

  int n=3;

  int cost = 0;
  if (sl < n || tl < n) {
    for (int i=0,ni=Math.min(sl,tl);i<ni;i++) {
      if (source.charAt(i) == target.charAt(i)) {
       cost++;
      }
    }
    return (float) cost/Math.max(sl, tl);
  }

  char[] sa = new char[sl+n-1];
  float p[]; //'previous' cost array, horizontally
  float d[]; // cost array, horizontally
 float _d[]; //placeholder to assist in swapping p and d

  //construct sa with prefix
  for (int i=0;i<sa.length;i++) {
    if (i < n-1) {
      sa[i]=0; //add prefix
    }
    else {
      sa[i] = source.charAt(i-n+1);
    }
  }
  p = new float[sl+1]; 
  d = new float[sl+1]; 

  // indexes into strings s and t
  int i; // iterates through source
  int j; // iterates through target

  char[] t_j = new char[n]; // jth n-gram of t

 for (i = 0; i<=sl; i++) {
     p[i] = i;
 }

 for (j = 1; j<=tl; j++) {
     //construct t_j n-gram 
     if (j < n) {
     for (int ti=0;ti<n-j;ti++) {
         t_j[ti]=0; //add prefix
       }
       for (int ti=n-j;ti<n;ti++) {
         t_j[ti]=target.charAt(ti-(n-j));
       }
     }
     else {
       t_j = target.substring(j-n, j).toCharArray();
     }
     d[0] = j;
     for (i=1; i<=sl; i++) {
         cost = 0;
         int tn=n;
         //compare sa to t_j
         for (int ni=0;ni<n;ni++) {
           if (sa[i-1+ni] != t_j[ni]) {
             cost++;
           }
           else if (sa[i-1+ni] == 0) { //discount matches on prefix
             tn--;
           }
       }
         float ec = (float) cost/tn;
         // minimum of cell to the left+1, to the top+1, diagonally left and up +cost
         d[i] = Math.min(Math.min(d[i-1]+1, p[i]+1),  p[i-1]+ec);
     }
     // copy current distance counts to 'previous row' distance counts
     _d = p;
     p = d;
     d = _d;
 }

 // our last action in the above loop was to switch d and p, so p now
 // actually has the most recent cost counts
 System.out.println(1.0f - (p[sl] / Math.max(tl, sl)));
 return 1.0f - (p[sl] / Math.max(tl, sl));

} 

}

Please HELP!

Thanks in advance...

Answer 1

When compiling Java classes to load into an Oracle database, be sure that you compile your Java classes to run with the JVM inside the Oracle database.

The version of Java that comes with an Oracle database is typically out of date compared to the current Java: expect to be using Java 1.4 with Oracle 10g and 1.5 with 11g. Your best bet is to use the Java compiler that ships with the database, but if you can't do that, use -target 1.5 or suchlike to force the compiler to compile classes to run on Java 1.5.