Java Return Framework - Return Results From Different Tiers Properly. This has been used a lot on www.ilikeplaces.com to perfect effect.

Return.java

package ai.ilikeplaces.util;

import ai.ilikeplaces.doc.License;
import ai.ilikeplaces.rbs.RBGet;

/**
 * Created by IntelliJ IDEA.
 * User: <a href="http://www.ilikeplaces.com"> http://www.ilikeplaces.com </a>
 * Date: Jan 1, 2010
 * Time: 4:26:30 PM
 */

@License(content = "This code is licensed under GNU AFFERO GENERAL PUBLIC LICENSE Version 3")
public interface Return<T> {

    final static public String YIKES_SOMETHING_WENT_WRONG = RBGet.gui().getString("YIKES_SOMETHING_WENT_WRONG");

    public int returnStatus();

    public long returnErrorSeqCode();

    public T returnValue();

    /**
     * Use to optimistically obtain return value assuming there were no errors. This will throw a runtime exception if
     * errors had occured.
     *
     * @return
     */
    public T returnValueBadly();

    public Throwable returnError();

    public String returnMsg();

    /**
     *
     * @return true if value of {@link #returnStatus()} == 0
     */
    public boolean valid();

    @Override
    public String toString();
}

ReturnImpl.java

package ai.ilikeplaces.util;

import ai.ilikeplaces.doc.License;

/**
 * Created by IntelliJ IDEA.
 * User: <a href="http://www.ilikeplaces.com"> http://www.ilikeplaces.com </a>
 * Date: Jan 1, 2010
 * Time: 4:29:55 PM
 */

@License(content = "This code is licensed under GNU AFFERO GENERAL PUBLIC LICENSE Version 3")
final public class ReturnImpl<T> implements Return<T> {

    final static private String logMsgBeginning = "SORRY! I ENCOUNTERED AN EXCEPTION! HOWEVER, THE APPLICATION SHOULD REMAIN INTACT. SEE BELOW FOR MORE DETAILS.\n\n";

    static private long ERROR_SEQ_NUMBER = 1;

    private int returnStatus = 1;

    private T returnValue = null;

    private Throwable returnError = null;

    private String returnMsg = null;

    public ReturnImpl(final int returnStatus, final T returnValue, final Throwable returnError, final String returnMsg) {
        this.returnStatus = returnStatus;
        this.returnValue = returnValue;
        this.returnError = returnError;
        this.returnMsg = returnMsg;
    }

    public ReturnImpl(final T returnValue, final String returnMsg) {
        this.returnStatus = 0;
        this.returnValue = returnValue;
        this.returnMsg = returnMsg;
    }

    public ReturnImpl(final Throwable returnError, final String returnMsg, final boolean shouldLog) {
        if (shouldLog) {
            Loggers.EXCEPTION.error(logMsgBeginning + returnMsg + "\n", returnError);
        }
        this.returnStatus = 1;
        this.returnError = returnError;
        this.returnMsg = returnMsg;
    }

    /**
     * Returns 0 if no error occurred, or a unique error code specific only to this error. This code can be given to
     * the user and can be grepped or resolved in any manner you require, later.
     *
     * The current return implementation had to go by int and expects the system will not exeed integer range. To get
     * the exact error code, check if the return status is greater than zero and if so, get the code separately.
     *
     * @return
     */
    @Override
    final public int returnStatus() {
        return returnStatus == 0 ? returnStatus : (int) ERROR_SEQ_NUMBER++;
    }

    /**
     * Returns a unique error code for this error, if any, or throws IllegalAccessError if otherwise.
     * @return Unique ERROR_SEQ_NUMBER
     */
    @Override
    final public long returnErrorSeqCode(){
        if(returnStatus == 0){
            throw new IllegalAccessError("SORRY! YOU CANNOT OBTAIN AN ERROR CODE WHEN THERE IS NO ERROR. PLEASE AVOID CALLING THIS METHOD IF NO ERROR IS FOUND.");
        }
        return ERROR_SEQ_NUMBER;
    }

    @Override
    final public T returnValue() {
        return returnValue;
    }

    @Override
    final public T returnValueBadly() {
        if (returnStatus() != 0) {
            throw new RuntimeException(returnError);
        }
        return returnValue;
    }

    @Override
    final public Throwable returnError() {
        return returnError;
    }

    @Override
    public String returnMsg() {
        return returnMsg;
    }

    @Override
    public boolean valid(){
        return returnStatus() == 0;
    }

    @Override
    public String toString() {
        return "Return{" +
                "returnStatus=" + returnStatus +
                ", returnValue=" + (returnValue != null ? returnValue.toString() : "null") +
                ", returnError=" + (returnError != null ? returnError.toString() : "null") +
                ", returnMsg='" + (returnMsg != null ? returnMsg : "") + '\'' +
                '}';
    }
}

Please let people at www.ilikeplaces.com know if you need this under Apache 2.0. We are just a bit too busy to do those small things ;-)