Java - find the first cause of an exception

Question

I need to check if an exception is caused by some database problem. I receive an Exception and check if its cause contains the \"ORA\" string and return that (something like

Answer 1

In the interests of not reinventing the wheel, if you're using Apache Commons Lang, then look at ExceptionUtils.getRootCause().

Is it worth including a library just for that? Maybe not. But if you already have it on your classpath, it's there for you, and note that it does some things that a 'naive' implementation might not do (e.g. deal with cycles in the cause chain... ugh!)

Answer 2

One line solution using core Java API:

    try {
        i = 1 / 0; 
    } catch (ArithmeticException e) {
        System.out.println(new ArithmeticException().initCause(e).getCause());
    }

One more solution below works as well:

    try {
        i = 1 / 0; 
    } catch (ArithmeticException e) {
        System.out.println(new Exception().initCause(e).getCause());
    }

Both of them will print

java.lang.ArithmeticException: / by zero

Answer 3

If the exception being thrown is always going to be of a specific type, like OracleException, you can catch just that exception.

For example:

try {

    ...

} catch(OracleException oe) {

    ...

}

This would only apply if there are specific Oracle exceptions being thrown. I don't know much about Oracle, so before attempting this you will probably want to find out if that's what's happening.

Answer 4

You could improve your code checking for SQLException

import java.sql.SQLException;

private static final String ORACLE = "ORA";

public String doHandle(Throwable t) {
    if (t.getClass().isAssignableFrom(SQLException.class)) {
    SQLException e = (SQLException) t;
    int errCode = e.getErrorCode();
    String state = e.getSQLState();
    String msg = e.getMessage();
    if (msg.contains(ORACLE)) {
        return msg;
        }
    } else {
        if (t.getCause() != null) {
            return this.doHandle(t.getCause());
            }
        }
    return "";
}

Also, I think in Oracle "errCode" contains the number associated to ORA-nnnn

Answer 5

on 28-01-2015 , i have unable to solve my problem with any of the above solution, so my recommendation is to use :

e.getMessage().toString();

Ps: i am using it on android.

Answer 6

Probably a bit overkill for your usage but I think it is cleaner (and reusable)

interface ThrowablePredicate {
    boolean accept(Throwable t);
}

public OracleErrorThrowablePredicate implements ThrowablePredicate {
    private static final ORA_ERR = "ORA";

    public boolean accept(Throwable t) {
        return t.toString().contains(ORA_ERR);
    }
}


public class CauseFinder {

   private ThrowablePredicate predicate;

   public CauseFinder(ThrowablePredicate predicate) {
      this.predicate = predicate;
   }

   Throwable findCause(Throwable t) {
      Throwable cause = t.getCause();

      return cause == null ? null 
         : predicate.accept(cause) ? cause : findCause(cause)
   }
}


// Your method
private String getErrorOracle(Throwable e){
    return new CauseFinder(new OracleErrorThrowablePredicate()).findCause(e);
}