QCon

java.lang.Object
- com.db4o.internal.query.processor.QCon

All Implemented Interfaces:

Visitor4, Constraint, Unversioned

Direct Known Subclasses:

QConEvaluation, QConJoin, QConObject, QConstraints, QConUnconditional
```
public abstract class QCon
extends java.lang.Object
implements Constraint, Visitor4, Unversioned
```
Base class for all constraints on queries.

Field Summary

Fields
Modifier and Type Field and Description

protected List4 _children

protected QE i_evaluator

protected QCon i_parent

Fields
Modifier and Type	Field and Description
`protected List4`	`_children`
`protected QE`	`i_evaluator`
`protected QCon`	`i_parent`

Constructor Summary

Constructors
Constructor and Description

QCon()

Constructors
Constructor and Description
`QCon()`

Method Summary

Methods
Modifier and Type	Method and Description
`Constraint`	`and(Constraint andWith)` links two Constraints for AND evaluation.
`Constraint`	`byExample()` set the evaluation mode to object comparison (query by example).
`boolean`	`canBeIndexLeaf()`
`boolean`	`canLoadByIndex()`
`int`	`childrenCount()`
`ObjectContainerBase`	`container()`
`Constraint`	`contains()` sets the evaluation mode to string contains comparison.
`Constraint`	`endsWith(boolean caseSensitive)` sets the evaluation mode to string endsWith comparison.
`Constraint`	`equal()` Used in conjunction with `Constraint.smaller()` or `Constraint.greater()` to create constraints like "smaller or equal", "greater or equal".
`QE`	`evaluator()`
`QField`	`getField()`
`java.lang.Object`	`getObject()` returns the Object the query graph was constrained with to create this `Constraint`.
`Constraint`	`greater()` sets the evaluation mode to `>`.
`boolean`	`hasChildren()`
`boolean`	`hasJoins()`
`boolean`	`hasObjectInParentPath(java.lang.Object obj)`
`boolean`	`hasParent()`
`int`	`id()`
`Constraint`	`identity()` sets the evaluation mode to identity comparison.
`int`	`identityID()`
`protected void`	`internalSetProcessedByIndex()`
`Iterator4`	`iterateChildren()`
`Iterator4`	`iterateJoins()`
`Constraint`	`like()` sets the evaluation mode to "like" comparison.
`Constraint`	`not()` turns on not() comparison.
`boolean`	`onSameFieldAs(QCon other)`
`Constraint`	`or(Constraint orWith)` links two Constraints for OR evaluation.
`QCon`	`parent()`
`boolean`	`processedByIndex()`
`void`	`setCandidates(QCandidates a_candidates)`
`void`	`setProcessedByIndex()`
`Constraint`	`smaller()` sets the evaluation mode to `<`.
`Constraint`	`startsWith(boolean caseSensitive)` sets the evaluation mode to string startsWith comparison.
`protected java.lang.Object`	`streamLock()`
`Transaction`	`transaction()`
`void`	`visit(java.lang.Object obj)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - _children
```
protected List4 _children
```
  - i_evaluator
```
protected QE i_evaluator
```
  - i_parent
```
protected QCon i_parent
```
- Constructor Detail
  - QCon
```
public QCon()
```
- Method Detail
  - container
```
public ObjectContainerBase container()
```
  - transaction
```
public Transaction transaction()
```
  - and
```
public Constraint and(Constraint andWith)
```
    Description copied from interface: Constraint
    
    links two Constraints for AND evaluation. For example:
    query.constrain(Pilot.class);
    query.descend("points").constrain(101).smaller().and(query.descend("name").constrain("Test Pilot0"));
    will retrieve all pilots with points less than 101 and name as "Test Pilot0"
    
    Specified by:
    
    and in interface Constraint
    
    Parameters:
    andWith - the other Constraint
    
    Returns:
    a new Constraint, that can be used for further calls to Constraint.and(Constraint) and Constraint.or(Constraint)
  - canBeIndexLeaf
```
public boolean canBeIndexLeaf()
```
  - canLoadByIndex
```
public boolean canLoadByIndex()
```
  - contains
```
public Constraint contains()
```
    Description copied from interface: Constraint
    
    sets the evaluation mode to string contains comparison. The contains comparison is case sensitive. For example:
    Pilot pilot = new Pilot("Test Pilot1", 100);
    container.store(pilot);
    ...
    query.constrain(Pilot.class);
    // All pilots with the name containing "est" will be retrieved
    query.descend("name").constrain("est").contains();
    
    Specified by:
    
    contains in interface Constraint
    
    Returns:
    this Constraint to allow the chaining of method calls.
    See Also:
    like() for case insensitive string comparison
  - equal
```
public Constraint equal()
```
    Description copied from interface: Constraint
    
    Used in conjunction with Constraint.smaller() or Constraint.greater() to create constraints like "smaller or equal", "greater or equal". For example:
    query.constrain(Pilot.class);
    query.descend("points").constrain(101).smaller().equal();
    will return all pilots with points <= 101.
    
    Specified by:
    
    equal in interface Constraint
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - getField
```
public QField getField()
```
  - getObject
```
public java.lang.Object getObject()
```
    Description copied from interface: Constraint
    
    returns the Object the query graph was constrained with to create this Constraint.
    
    Specified by:
    
    getObject in interface Constraint
    
    Returns:
    Object the constraining object.
  - greater
```
public Constraint greater()
```
    Description copied from interface: Constraint
    
    sets the evaluation mode to >. For example:
    query.constrain(Pilot.class);
    query.descend("points").constrain(101).greater()
    will return all pilots with points > 101.
    
    Specified by:
    
    greater in interface Constraint
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - hasChildren
```
public boolean hasChildren()
```
  - hasParent
```
public boolean hasParent()
```
  - parent
```
public QCon parent()
```
  - hasJoins
```
public boolean hasJoins()
```
  - hasObjectInParentPath
```
public boolean hasObjectInParentPath(java.lang.Object obj)
```
  - identity
```
public Constraint identity()
```
    Description copied from interface: Constraint
    
    sets the evaluation mode to identity comparison. In this case only objects having the same database identity will be included in the result set. For example:
    Pilot pilot = new Pilot("Test Pilot1", 100);
    Car car = new Car("BMW", pilot);
    container.store(car);
    // Change the name, the pilot instance stays the same
    pilot.setName("Test Pilot2");
    // create a new car
    car = new Car("Ferrari", pilot);
    container.store(car);
    Query query = container.query();
    query.constrain(Car.class);
    // All cars having pilot with the same database identity
    // will be retrieved. As we only created Pilot object once
    // it should mean all car objects
    query.descend("_pilot").constrain(pilot).identity();
    
    Specified by:
    
    identity in interface Constraint
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - byExample
```
public Constraint byExample()
```
    Description copied from interface: Constraint
    
    set the evaluation mode to object comparison (query by example).
    
    Specified by:
    
    byExample in interface Constraint
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - identityID
```
public int identityID()
```
  - iterateJoins
```
public Iterator4 iterateJoins()
```
  - iterateChildren
```
public Iterator4 iterateChildren()
```
  - like
```
public Constraint like()
```
    Description copied from interface: Constraint
    
    sets the evaluation mode to "like" comparison. This mode will include all objects having the constrain expression somewhere inside the string field. For example:
    Pilot pilot = new Pilot("Test Pilot1", 100);
    container.store(pilot);
    ...
    query.constrain(Pilot.class);
    // All pilots with the name containing "est" will be retrieved
    query.descend("name").constrain("est").like();
    
    Specified by:
    
    like in interface Constraint
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - startsWith
```
public Constraint startsWith(boolean caseSensitive)
```
    Description copied from interface: Constraint
    
    sets the evaluation mode to string startsWith comparison. For example:
    Pilot pilot = new Pilot("Test Pilot0", 100);
    container.store(pilot);
    ...
    query.constrain(Pilot.class);
    query.descend("name").constrain("Test").startsWith(true);
    
    Specified by:
    
    startsWith in interface Constraint
    
    Parameters:
    caseSensitive - comparison will be case sensitive if true, case insensitive otherwise
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - endsWith
```
public Constraint endsWith(boolean caseSensitive)
```
    Description copied from interface: Constraint
    
    sets the evaluation mode to string endsWith comparison. For example:
    Pilot pilot = new Pilot("Test Pilot0", 100);
    container.store(pilot);
    ...
    query.constrain(Pilot.class);
    query.descend("name").constrain("T0").endsWith(false);
    
    Specified by:
    
    endsWith in interface Constraint
    
    Parameters:
    caseSensitive - comparison will be case sensitive if true, case insensitive otherwise
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - not
```
public Constraint not()
```
    Description copied from interface: Constraint
    
    turns on not() comparison. All objects not fullfilling the constrain condition will be returned. For example:
    Pilot pilot = new Pilot("Test Pilot1", 100);
    container.store(pilot);
    ...
    query.constrain(Pilot.class);
    query.descend("name").constrain("t0").endsWith(true).not();
    
    Specified by:
    
    not in interface Constraint
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - onSameFieldAs
```
public boolean onSameFieldAs(QCon other)
```
    Parameters:
    other -
  - or
```
public Constraint or(Constraint orWith)
```
    Description copied from interface: Constraint
    
    links two Constraints for OR evaluation. For example:
    
    query.constrain(Pilot.class);
    query.descend("points").constrain(101).greater().or(query.descend("name").constrain("Test Pilot0"));
    will retrieve all pilots with points more than 101 or pilots with the name "Test Pilot0"
    
    Specified by:
    
    or in interface Constraint
    
    Parameters:
    orWith - the other Constraint
    
    Returns:
    a new Constraint, that can be used for further calls to Constraint.and(Constraint) and Constraint.or(Constraint)
  - setCandidates
```
public void setCandidates(QCandidates a_candidates)
```
  - smaller
```
public Constraint smaller()
```
    Description copied from interface: Constraint
    
    sets the evaluation mode to <. For example:
    query.constrain(Pilot.class);
    query.descend("points").constrain(101).smaller()
    will return all pilots with points < 101.
    
    Specified by:
    
    smaller in interface Constraint
    
    Returns:
    this Constraint to allow the chaining of method calls.
  - streamLock
```
protected java.lang.Object streamLock()
```
  - visit
```
public void visit(java.lang.Object obj)
```
    Specified by:
    
    visit in interface Visitor4
  - evaluator
```
public QE evaluator()
```
  - setProcessedByIndex
```
public void setProcessedByIndex()
```
  - internalSetProcessedByIndex
```
protected void internalSetProcessedByIndex()
```
  - processedByIndex
```
public boolean processedByIndex()
```
  - childrenCount
```
public int childrenCount()
```
  - id
```
public int id()
```

Class QCon

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

_children

i_evaluator

i_parent

Constructor Detail

QCon

Method Detail

container

transaction

and

canBeIndexLeaf

canLoadByIndex

contains

equal

getField

getObject

greater

hasChildren

hasParent

parent

hasJoins

hasObjectInParentPath

identity

byExample

identityID

iterateJoins

iterateChildren

like

startsWith

endsWith

not

onSameFieldAs

or

setCandidates

smaller

streamLock

visit

evaluator

setProcessedByIndex

internalSetProcessedByIndex

processedByIndex

childrenCount

id