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Plugin for DataNucleus providing persistence to RDBMS datastores.

There is a newer version: 6.0.8

/**********************************************************************
Copyright (c) 2003 Mike Martin (TJDO) and others. All rights reserved. 
Licensed 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. 
 

Contributors:
2004 Andy Jefferson - equality operator
2004 Erik Bengtson - addInheritedColumn() for app-id
    ...
**********************************************************************/
package org.datanucleus.store.rdbms.key;

import org.datanucleus.store.rdbms.table.Column;
import org.datanucleus.store.rdbms.table.Table;

/**
 * Representation of a Candidate key.
 * This represents a UNIQUE key on a column or columns.
 */
public class CandidateKey extends Key
{
    /**
     * Constructor.
     * @param table Table to apply this key to
     */
    public CandidateKey(Table table)
    {
        super(table);
    }

    /**
     * Mutator for the column spec, to add/change a column.
     * @param seq Sequence number of the column
     * @param col The column
     */
    public void setColumn(int seq, Column col)
    {
        assertSameDatastoreObject(col);

        setMinSize(columns, seq + 1);

        if (columns.get(seq) != null)
        {
            //throw new JDOFatalInternalException("Key part #" + seq + " for " + table + " already set");
        }

        columns.set(seq, col);
    }

    /**
     * Accessor for the size.
     * @return The size.
     **/
    public int size()
    {
        return columns.size();
    }

    /**
     * Equality operator.
     * @param obj The object to compare against
     * @return Whether the objects are equal
     */
    public boolean equals(Object obj)
    {
        if (obj == this)
        {
            return true;
        }

        if (!(obj instanceof CandidateKey))
        {
            return false;
        }

        return super.equals(obj);
    }

    /**
     * Stringify method.
     * @return String version of this object.
     **/
    public String toString()
    {
        StringBuffer s = new StringBuffer("UNIQUE ").append(getColumnList(columns));

        return s.toString();
    }
}