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## org.apache.openjpa.datacache
Class QueryKey

    java.lang.Object
      org.apache.openjpa.datacache.QueryKey

All Implemented Interfaces:
  Externalizable, Serializable

    public class QueryKey

extends Object
implements Externalizable

This class stores information about a particular invocation of a query. It contains a reference to the external properties of the query that was executed, as well as any parameters used to execute that query, with one exception: first-class objects used as parameter values are converted to OIDs.

Author:
  Patrick Linskey
See Also:
  Serialized Form

Constructor Summary
`QueryKey()` Public constructor for externalization only.

Method Summary
`boolean` | `changeInvalidatesQuery(Collection changed)` Returns `true` if modifications to any of the classes in `changed` results in a possible invalidation of this query; otherwise returns `false`.
`boolean` | `equals(Object ob)` Determine equality based on identifying information.
`String` | `getCandidateTypeName()` Returns the candidate class name for this query.
`int` | `getTimeout()` Return the amount of time this key is good for.
`int` | `hashCode()` Define a hashing algorithm corresponding to the `equals(java.lang.Object)` method defined above.
`static QueryKey` | `newInstance(Query q)` Return a key for the given query, or null if it is not cacheable.
`static QueryKey` | `newInstance(Query q, Map args)` Return a key for the given query, or null if it is not cacheable.
`static QueryKey` | `newInstance(Query q, Object[] args)` Return a key for the given query, or null if it is not cacheable.
`void` | `readExternal(ObjectInput in)`
`String` | `toString()`
`void` | `writeExternal(ObjectOutput out)`

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Constructor Detail

### QueryKey

    public QueryKey()

  Public constructor for externalization only.

Method Detail

### newInstance

    public static QueryKey newInstance(Query q)

  Return a key for the given query, or null if it is not cacheable.

### newInstance

    public static QueryKey newInstance(Query q,
                                       Object[] args)

  Return a key for the given query, or null if it is not cacheable.

### newInstance

    public static QueryKey newInstance(Query q,
                                       Map args)

  Return a key for the given query, or null if it is not cacheable.

### getCandidateTypeName

    public String getCandidateTypeName()

  Returns the candidate class name for this query.

### getTimeout

    public int getTimeout()

  Return the amount of time this key is good for.

### changeInvalidatesQuery

    public boolean changeInvalidatesQuery(Collection changed)

  Returns `true` if modifications to any of the classes in `changed` results in a possible invalidation of this query; otherwise returns `false`. Invalidation is possible if one or more of the classes in this query key's access path has been changed.

### equals

    public boolean equals(Object ob)

  Determine equality based on identifying information. Keys created for queries that specify a candidate collection are always not equal.

  Overrides:
    `equals` in class `Object`

### hashCode

    public int hashCode()

  Define a hashing algorithm corresponding to the `equals(java.lang.Object)` method defined above.

  Overrides:
    `hashCode` in class `Object`

### toString

    public String toString()

  Overrides:
    `toString` in class `Object`

### writeExternal

    public void writeExternal(ObjectOutput out)
                       throws IOException

  Specified by:
    `writeExternal` in interface `Externalizable`
  Throws:
    `IOException`

### readExternal

    public void readExternal(ObjectInput in)
                      throws IOException,
                             ClassNotFoundException

  Specified by:
    `readExternal` in interface `Externalizable`
  Throws:
    `IOException`
    `ClassNotFoundException`

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Copyright © 2006 Apache Software Foundation. All Rights Reserved.