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java.lang.Object com.sun.jna.Structure com.sun.jna.Union
public abstract class Union
Represents a native union. When writing to native memory, the field
corresponding to the type passed to setType(java.lang.Class)
will be written
to native memory. Upon reading from native memory, Structure, String,
or WString fields will not be initialized unless they are
the current field as identified by a call to setType(java.lang.Class)
. The current
field is always unset by default to avoid accidentally attempting to read
a field that is not valid. In the case of a String, for instance, an
invalid pointer may result in a memory fault when attempting to initialize
the String.
Nested Class Summary |
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Nested classes/interfaces inherited from class com.sun.jna.Structure |
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Structure.ByReference, Structure.ByValue, Structure.FFIType, Structure.StructField |
Field Summary |
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Fields inherited from class com.sun.jna.Structure |
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ALIGN_DEFAULT, ALIGN_GNUC, ALIGN_MSVC, ALIGN_NONE, CALCULATE_SIZE, fieldOrder, layoutInfo |
Constructor Summary | |
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protected |
Union()
Create a Union whose size and alignment will be calculated automatically. |
protected |
Union(Pointer p)
Create a Union of the given size, using default alignment. |
protected |
Union(Pointer p,
int alignType)
Create a Union of the given size and alignment type. |
protected |
Union(Pointer p,
int alignType,
TypeMapper mapper)
Create a Union of the given size and alignment type. |
protected |
Union(TypeMapper mapper)
Create a Union of the given size and alignment type. |
Method Summary | |
---|---|
protected List |
getFieldOrder()
Unions do not need a field order, so automatically provide a value to satisfy checking in the Structure superclass. |
protected int |
getNativeAlignment(Class type,
Object value,
boolean isFirstElement)
All fields are considered the "first" element. |
Object |
getTypedValue(Class type)
Reads the Structure field of the given type from memory, sets it as the active type and returns it. |
Object |
readField(String fieldName)
Force a read of the given field from native memory. |
protected Object |
readField(Structure.StructField field)
Avoid reading pointer-based fields and structures unless explicitly selected. |
void |
setType(Class type)
Indicates by type which field will be used to write to native memory. |
void |
setType(String fieldName)
Indicates which field will be used to write to native memory. |
Object |
setTypedValue(Object object)
Set the active type and its value. |
void |
writeField(String fieldName)
Write the given field value to native memory. |
void |
writeField(String fieldName,
Object value)
Write the given field value to the field and native memory. |
protected void |
writeField(Structure.StructField field)
Only the currently selected field will be written. |
Methods inherited from class com.sun.jna.Structure |
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allocateMemory, allocateMemory, autoAllocate, autoRead, autoRead, autoWrite, autoWrite, busy, cacheTypeInfo, calculateSize, clear, conditionalAutoRead, ensureAllocated, equals, fieldOffset, fields, getAutoRead, getAutoWrite, getFieldList, getFields, getFieldTypeInfo, getFieldValue, getNativeSize, getNativeSize, getPointer, getStringEncoding, getStructAlignment, getTypeInfo, getTypeInfo, getTypeMapper, hashCode, newInstance, newInstance, read, reading, setAlignType, setAutoRead, setAutoSynch, setAutoWrite, setFieldOrder, setFieldValue, setStringEncoding, size, size, size, sortFields, toArray, toArray, toString, toString, typeInfoField, updateStructureByReference, useMemory, useMemory, validate, write |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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protected Union()
protected Union(Pointer p)
protected Union(Pointer p, int alignType)
protected Union(TypeMapper mapper)
protected Union(Pointer p, int alignType, TypeMapper mapper)
Method Detail |
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protected List getFieldOrder()
getFieldOrder
in class Structure
public void setType(Class type)
setType(String)
instead with the field name.
IllegalArgumentException
- if the type does not correspond to
any declared union field.public void setType(String fieldName)
IllegalArgumentException
- if the name does not correspond to
any declared union field.public Object readField(String fieldName)
readField
in class Structure
IllegalArgumentException
- if no field exists with the given namepublic void writeField(String fieldName)
writeField
in class Structure
IllegalArgumentException
- if no field exists with the given namepublic void writeField(String fieldName, Object value)
writeField
in class Structure
IllegalArgumentException
- if no field exists with the given namepublic Object getTypedValue(Class type)
Union u;
Class type;
u.setType(type);
u.read();
value = u.field;
type
- class type of the Structure field to read
public Object setTypedValue(Object object)
Union u;
Class type;
u.setType(type);
u.field = value;
object
- instance of a class which is part of the union
protected void writeField(Structure.StructField field)
writeField
in class Structure
protected Object readField(Structure.StructField field)
readField
in class Structure
protected int getNativeAlignment(Class type, Object value, boolean isFirstElement)
getNativeAlignment
in class Structure
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