com.goldencode.p2j.util

Class jobject<T>

java.lang.Object

com.goldencode.p2j.util.LazyUndoable

com.goldencode.p2j.util.BaseDataType

com.goldencode.p2j.util.jobject<T>

All Implemented Interfaces:

Undoable, java.io.Externalizable, java.io.Serializable, java.lang.Comparable

public class jobject<T>
extends BaseDataType

Wrapper class for all Java instances accessed from legacy 4GL code.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.goldencode.p2j.util.BaseDataType

BaseDataType.Type, BaseDataType.WrapperHandler

Field Summary

Fields

Modifier and Type	Field and Description
private T	ref The contained Java instance.
private java.lang.Class<T>	type The object's type.

Constructor Summary

Constructors

Constructor and Description
jobject() Default constructor.
jobject(BaseDataType value) Create a new jobject and assign it the given value.
jobject(java.lang.Class<? extends java.lang.Object> type) Initialize this object reference, allowing only assignment to objects compatible with the specified type.
jobject(java.lang.Class<? extends java.lang.Object> type, BaseDataType value) Create a new jobject with the specified type and assign it the given value.
jobject(jobject<T> other) Copy constructor.
jobject(T ref) Initialize this object with the given reference.

Method Summary

Modifier and Type	Method and Description
void	assign(BaseDataType value) Sets the state (data and unknown value) of this instance based on the state of the passed instance.
void	assign(jobject<?> value) Assign the current instance reference to the referenced wrapped by the specified value.
void	assign(java.lang.Object ref) Set this instance ref to the specified value, directly.
void	assign(Undoable old) Modify the contained data of the instance to copy the instance data from the given instance.
int	compareTo(java.lang.Object obj) Compares this instance with the specified instance and returns -1 if this instance is less than the specified, 0 if the two instances are equal and 1 if this instance is greater than the specified instance.
java.lang.String	defaultFormatString() Return the default display format string for this type.
jobject<T>	duplicate() Does the same as standard clone() method but returns an instance of BaseDataType and doesn't throw the CloneNotSupportedException.
static <T extends BaseDataType> T	fromJava(java.lang.Class<T> type, jobject<?> value) Convert the given Java-style value to a BDT instance.
(package private) static <T extends BaseDataType> T	fromJava(jobject<?> value) Convert the given Java-style value to a BDT instance.
BaseDataType.Type	getType() Get the type
int	hashCode() A minimal implementation which satisfies the need for a concrete method.
BaseDataType	instantiateDefault() Creates a new instance of the same type that represents the default initialized value.
BaseDataType	instantiateUnknown() Creates a new instance of the same type that represents the unknown value.
boolean	isUnknown() Reports if this instance represents the unknown value.
logical	isValid() Determines if this instance is valid (to be used).
void	readExternal(java.io.ObjectInput in) Replacement for the default object reading method.
T	ref() Return the wrapped reference if this instance is not set to unknown value.
(package private) void	set(java.lang.Object ref) Set this object's reference and type from the given instance.
void	setUnknown() Sets the state of this instance's unknown value flag or state to true.
static <T> jobject<T>	toJava(BaseDataType value) Convert the given BDT value to a jobject instance.
static <T> jobject<T>	toJava(java.lang.Class<T> type, BaseDataType value) Convert the given BDT value to a jobject instance.
private static java.lang.Object	toJavaInstance(java.lang.Class<?> type, BaseDataType value) Convert the specified legacy BDT value to a Java-compatible instance.
java.lang.String	toString(java.lang.String fmt) Creates a string representation of the instance data using the given format string.
java.lang.String	toStringExport() Creates a string representation of the instance data using the 'export' format.
java.lang.String	toStringMessage() Creates a string representation of the instance data in a form that is compatible with the MESSAGE language statement.
(package private) java.lang.Class<T>	type() Get the object's declared class.
void	writeExternal(java.io.ObjectOutput out) Replacement for the default object writing method.

Methods inherited from class com.goldencode.p2j.util.BaseDataType

calcFormatLength, createProxy, createProxy, deepCopy, elementsOfType, equals, fallback, formatLength, fromTypeName, generateDefault, generateUnknown, getAssigner, getSize, getTypeName, incompatibleTypesOnConversion, initialize, initializeDefaultExtent, instantiateDefaultExtent, invalidInitializer, isAllKnown, isAllKnown, isAssignDirect, isIncompatibleTypesOnConversion, isProxy, isUnknownValue, maximum, minimum, notUnknownValue, sameType, val, variable

Methods inherited from class com.goldencode.p2j.util.LazyUndoable

changed, checkUndoable, checkUndoable, checkUndoable, getTransLevel, isGlobal, isUndoable, markUndoable, popBlock, rollback, setGlobal

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

ref

private T ref

The contained Java instance. null is unknown value.

type

private java.lang.Class<T> type

The object's type.

Constructor Detail

jobject

public jobject()

Default constructor.

jobject

public jobject(java.lang.Class<? extends java.lang.Object> type,
               BaseDataType value)

Create a new jobject with the specified type and assign it the given value.

Parameters:

type - The expected type.

value - The reference. If needed, convert from legacy 4GL type to Java.

jobject

public jobject(BaseDataType value)

Create a new jobject and assign it the given value.

Parameters:

value - The reference. If needed, convert from legacy 4GL type to Java.

jobject

public jobject(java.lang.Class<? extends java.lang.Object> type)

Initialize this object reference, allowing only assignment to objects compatible with the specified type.

Parameters:

type - The type of references this object can hold.

jobject

public jobject(T ref)

Initialize this object with the given reference.

Parameters:

ref - The reference.

jobject

public jobject(jobject<T> other)

Copy constructor.

Parameters:

other - The object from which to copy.

Method Detail

toJava

public static <T> jobject<T> toJava(BaseDataType value)

Convert the given BDT value to a jobject instance.

Parameters:

value - The BDT instance to be converted to Java.

Returns:

A jobject instance wrapping the converted value. Note that if the conversion is not possible, then an ERROR condition will be thrown.

toJava

public static <T> jobject<T> toJava(java.lang.Class<T> type,
                                    BaseDataType value)

Convert the given BDT value to a jobject instance.

Parameters:

type - The expected type.

value - The BDT instance to be converted to Java.

Returns:

A jobject instance wrapping the converted value. Note that if the conversion is not possible, then a ERROR condition will be thrown.

fromJava

public static <T extends BaseDataType> T fromJava(java.lang.Class<T> type,
                                                  jobject<?> value)

Convert the given Java-style value to a BDT instance.

Parameters:

type - The expected BDT instance for the value.

value - The jobject wrapping a Java-style value.

Returns:

The converted BDT value.

fromJava

static <T extends BaseDataType> T fromJava(jobject<?> value)

Convert the given Java-style value to a BDT instance.

Parameters:

value - The jobject wrapping a Java-style value.

Returns:

The converted BDT value.

ref

public T ref()

Return the wrapped reference if this instance is not set to unknown value.

Returns:

The contained reference or raise an error if this is unknown value.

compareTo

public int compareTo(java.lang.Object obj)

Compares this instance with the specified instance and returns -1 if this instance is less than the specified, 0 if the two instances are equal and 1 if this instance is greater than the specified instance. This is the implementation of the Comparable interface.

The algorithm will fail to give meaningful results in the case where one tries to sort against other objects that do not represent compatible values.

Parameters:

obj - The instance to compare against.

Returns:

≤-1, 0, or ≥1 depending on if this instance is less than, equal to or greater (respectively) than the specified instance obj.

hashCode

public int hashCode()

A minimal implementation which satisfies the need for a concrete method.

Specified by:

hashCode in class BaseDataType

Returns:

The hash code for this object instance.

assign

public void assign(java.lang.Object ref)

Set this instance ref to the specified value, directly.

If ref is null, it will be set to unknown.

If the type is not compatible with ref, an error condition is raised.

Overrides:

assign in class BaseDataType

Parameters:

ref - The instance to assign.

assign

public void assign(jobject<?> value)

Assign the current instance reference to the referenced wrapped by the specified value.

Overrides:

assign in class BaseDataType

Parameters:

value - The Java-style wrapped reference.

getType

public BaseDataType.Type getType()

Get the type

Specified by:

getType in class BaseDataType

Returns:

type

assign

public void assign(BaseDataType value)

Sets the state (data and unknown value) of this instance based on the state of the passed instance.

If the value is not of the same type, some form of automatic type conversion may occur, or an error will be raised.

This variant is meant to handle the cases of built-in functions and methods in the 4GL which have polymorphic return types (e.g. DYNAMIC-FUNCTION()). This should NOT be used for non-polymorphic assignments.

Specified by:

assign in class BaseDataType

Parameters:

value - The instance from which to copy state.

assign

public void assign(Undoable old)

Modify the contained data of the instance to copy the instance data from the given instance. Generally, the class of the given instance must match the class upon which the assign method is called, although this is not a strict requirement.

Parameters:

old - The backup instance from which to copy data.

isUnknown

public boolean isUnknown()

Reports if this instance represents the unknown value.

Specified by:

isUnknown in class BaseDataType

Returns:

true if this instance is set to the unknown value.

isValid

public logical isValid()

Determines if this instance is valid (to be used).

Returns:

true if this instance can be used.

setUnknown

public void setUnknown()

Sets the state of this instance's unknown value flag or state to true.

Warning: the data stored in this instance will be invalid after calling this method.

Specified by:

setUnknown in class BaseDataType

duplicate

public jobject<T> duplicate()

Does the same as standard clone() method but returns an instance of BaseDataType and doesn't throw the CloneNotSupportedException.

Specified by:

duplicate in class BaseDataType

Returns:

A clone of this instance.

instantiateUnknown

public BaseDataType instantiateUnknown()

Creates a new instance of the same type that represents the unknown value.

Specified by:

instantiateUnknown in class BaseDataType

Returns:

An instance that represents the unknown value.

toString

public java.lang.String toString(java.lang.String fmt)

Creates a string representation of the instance data using the given format string. If the instance represents the unknown value, a '?' will be returned.

Specified by:

toString in class BaseDataType

Parameters:

fmt - The format string to use.

Returns:

The formatted string.

toStringMessage

public java.lang.String toStringMessage()

Creates a string representation of the instance data in a form that is compatible with the MESSAGE language statement. If the instance represents the unknown value, a '?' will be returned.

Specified by:

toStringMessage in class BaseDataType

Returns:

The 'message' formatted string.

toStringExport

public java.lang.String toStringExport()

Creates a string representation of the instance data using the 'export' format. If the instance represents the unknown value, a '?' will be returned.

Specified by:

toStringExport in class BaseDataType

Returns:

The 'export' formatted string.

defaultFormatString

public java.lang.String defaultFormatString()

Return the default display format string for this type.

Specified by:

defaultFormatString in class BaseDataType

Returns:

The default format string.

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Replacement for the default object reading method. The latest state is read from the input source.

Parameters:

in - The input source from which fields will be restored.

Throws:

java.io.NotSerializableException - Always, as legacy objects can't be serialized.

java.io.IOException

java.lang.ClassNotFoundException

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Replacement for the default object writing method. The latest state is written to the output destination.

Parameters:

out - The output destination to which fields will be saved.

Throws:

java.io.NotSerializableException - Always, as legacy objects can't be serialized.

java.io.IOException

set

void set(java.lang.Object ref)

Set this object's reference and type from the given instance.

Parameters:

ref - The object instance.

type

java.lang.Class<T> type()

Get the object's declared class.

Returns:

The type.

instantiateDefault

public BaseDataType instantiateDefault()

Creates a new instance of the same type that represents the default initialized value.

Specified by:

instantiateDefault in class BaseDataType

Returns:

An instance that represents the default value.

toJavaInstance

private static java.lang.Object toJavaInstance(java.lang.Class<?> type,
                                               BaseDataType value)

Convert the specified legacy BDT value to a Java-compatible instance.

Parameters:

type - The expected type of the Java instance.

value - The legacy BDT value.

Returns:

The converted Java instance; ERROR condition is raised if conversion is not possible.