org.apache.derbyDemo.scores.proc.Functions.java Source code

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Here is the source code for org.apache.derbyDemo.scores.proc.Functions.java

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/*
    
   Derby - Class org.apache.derbyDemo.scores.proc.Functions
    
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at
    
  http://www.apache.org/licenses/LICENSE-2.0
    
   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
    
 */

package org.apache.derbyDemo.scores.proc;

import java.sql.*;
import java.text.*;
import java.util.*;

import org.apache.commons.math.stat.descriptive.rank.Median;

import org.apache.derbyDemo.scores.util.*;

/**
 * <p>
 * Functions used by the Scores application.
 * </p>
 *
 */
public class Functions {
    ////////////////////////////////////////////////////////
    //
    // CONSTANTS
    //
    ////////////////////////////////////////////////////////

    public static final long MILLISECONDS_IN_YEAR = 1000L * 60L * 60L * 24L * 365L;

    ////////////////////////////////////////////////////////
    //
    // STATE
    //
    ////////////////////////////////////////////////////////

    ////////////////////////////////////////////////////////
    //
    // STATIC BEHAVIOR
    //
    ////////////////////////////////////////////////////////

    /**
     * <p>
     * Check that a legal answer was given to a question.
     * Throws an exception if it is not.
     * </p>
     */
    public static int vetChoice(int actualChoice, int questionID) throws SQLException {
        Connection conn = getDefaultConnection();
        int column = 1;

        PreparedStatement ps = Utils.prepare(conn,
                "select numberOfChoices, questionName\n" + "from Question\n" + "where questionID = ?\n");

        ps.setInt(1, questionID);

        ResultSet rs = ps.executeQuery();

        rs.next();

        int numberOfChoices = rs.getInt(column++);
        String questionName = rs.getString(column++);

        Utils.close(rs);
        Utils.close(ps);

        if ((actualChoice >= -1) && (actualChoice < numberOfChoices)) {
            return 1;
        } else {
            throw new SQLException("Illegal answer " + actualChoice + " given to question " + questionName);
        }
    }

    /**
     * <p>
     * Compute a Student's age given their birthday.
     * </p>
     */
    public static int computeAge(java.sql.Date date) {
        long interval = System.currentTimeMillis() - date.getTime();
        return (int) (interval / MILLISECONDS_IN_YEAR);
    }

    /**
     * <p>
     * Compute the relative weight of a Question given its difficulty.
     * </p>
     */
    public static double weighQuestion(int difficulty) {
        return Utils.weighQuestion(difficulty);
    }

    /**
     * <p>
     * Compute the score for a question. A penalty is assessed
     * for guessing the wrong answer. If actualChoice is -1,
     * then the Student didn't guess and we don't assess a penalty.
     * </p>
     */
    public static double scoreAnswer(int difficulty, int numberOfChoices, int correctChoice, int actualChoice) {
        return Utils.scoreAnswer(difficulty, numberOfChoices, correctChoice, actualChoice);
    }

    /**
     * <p>
     * Calculate the median score achieved on a Test.
     * </p>
     */
    public static double getMedianTestScore(int testID) throws SQLException {
        Logger log = Logger.getLogger();
        boolean loggingEnabled = log.isLoggingEnabled();
        Median median = new Median();
        ArrayList arraylist = new ArrayList();
        Connection conn = getDefaultConnection();

        try {
            log.enableLogging(false);

            PreparedStatement ps = Utils.prepare(conn, "select tk.score\n" + "from TestTaking tk, LastTaking lt\n"
                    + "where tk.takingID = lt.takingID\n" + "and tk.testID = ?\n");

            ps.setInt(1, testID);

            ResultSet rs = ps.executeQuery();

            while (rs.next()) {
                arraylist.add(new Double(rs.getDouble(1)));
            }

            Utils.close(rs);
            Utils.close(ps);
        } finally {
            log.enableLogging(loggingEnabled);
        }

        int count = arraylist.size();
        double values[] = new double[count];

        for (int i = 0; i < count; i++) {
            values[i] = ((Double) arraylist.get(i)).doubleValue();
        }

        return median.evaluate(values);
    }

    /**
     * <p>
     * Format a double as a percentage, suitable for printing.
     * </p>
     */
    public static String formatPercent(double score) throws SQLException {
        int rounded = (int) score;
        NumberFormat nf = NumberFormat.getNumberInstance();

        return nf.format(rounded);
    }

    /**
     * <p>
     * Get the default connection, called from inside the database engine.
     * </p>
     */
    static Connection getDefaultConnection() throws SQLException {
        return DriverManager.getConnection("jdbc:default:connection");
    }

}