Class BitField
int, short or
byte.
Each BitField is constructed with a mask value, which indicates
the bits that will be used to store and retrieve the data for that field.
For instance, the mask 0xFF indicates the least-significant byte
should be used to store the data.
As an example, consider a car painting machine that accepts paint instructions as integers. Bit fields can be used to encode this:
// blue, green and red are 1 byte values (0-255) stored in the three least
// significant bytes
BitField blue = new BitField(0xFF);
BitField green = new BitField(0xFF00);
BitField red = new BitField(0xFF0000);
// anyColor is a flag triggered if any color is used
BitField anyColor = new BitField(0xFFFFFF);
// isMetallic is a single bit flag
BitField isMetallic = new BitField(0x1000000);
Using these BitField instances, a paint instruction can be
encoded into an integer:
int paintInstruction = 0;
paintInstruction = red.setValue(paintInstruction, 35);
paintInstruction = green.setValue(paintInstruction, 100);
paintInstruction = blue.setValue(paintInstruction, 255);
Flags and data can be retrieved from the integer:
// Prints true if red, green or blue is non-zero
System.out.println(anyColor.isSet(paintInstruction)); // prints true
// Prints value of red, green and blue
System.out.println(red.getValue(paintInstruction)); // prints 35
System.out.println(green.getValue(paintInstruction)); // prints 100
System.out.println(blue.getValue(paintInstruction)); // prints 255
// Prints true if isMetallic was set
System.out.println(isMetallic.isSet(paintInstruction)); // prints false
- Since:
- 2.0
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionintclear(int holder) Clears the bits.byteclearByte(byte holder) Clears the bits.shortclearShort(short holder) Clears the bits.intgetRawValue(int holder) Obtains the value for the specified BitField, unshifted.shortgetShortRawValue(short holder) Obtains the value for the specified BitField, unshifted.shortgetShortValue(short holder) Obtains the value for the specified BitField, appropriately shifted right, as a short.intgetValue(int holder) Obtains the value for the specified BitField, appropriately shifted right.booleanisAllSet(int holder) Returns whether all of the bits are set or not.booleanisSet(int holder) Returns whether the field is set or not.intset(int holder) Sets the bits.intsetBoolean(int holder, boolean flag) Sets a boolean BitField.bytesetByte(byte holder) Sets the bits.bytesetByteBoolean(byte holder, boolean flag) Sets a boolean BitField.shortsetShort(short holder) Sets the bits.shortsetShortBoolean(short holder, boolean flag) Sets a boolean BitField.shortsetShortValue(short holder, short value) Replaces the bits with new values.intsetValue(int holder, int value) Replaces the bits with new values.
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Constructor Details
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BitField
Creates a BitField instance.- Parameters:
mask- the mask specifying which bits apply to this BitField. Bits that are set in this mask are the bits that this BitField operates on
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Method Details
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clear
Clears the bits.- Parameters:
holder- the int data containing the bits we're interested in- Returns:
- the value of holder with the specified bits cleared
(set to
0)
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clearByte
Clears the bits.- Parameters:
holder- the byte data containing the bits we're interested in- Returns:
- the value of holder with the specified bits cleared
(set to
0)
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clearShort
Clears the bits.- Parameters:
holder- the short data containing the bits we're interested in- Returns:
- the value of holder with the specified bits cleared
(set to
0)
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getRawValue
Obtains the value for the specified BitField, unshifted.- Parameters:
holder- the int data containing the bits we're interested in- Returns:
- the selected bits
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getShortRawValue
Obtains the value for the specified BitField, unshifted.- Parameters:
holder- the short data containing the bits we're interested in- Returns:
- the selected bits
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getShortValue
Obtains the value for the specified BitField, appropriately shifted right, as a short.Many users of a BitField will want to treat the specified bits as an int value, and will not want to be aware that the value is stored as a BitField (and so shifted left so many bits).
- Parameters:
holder- the short data containing the bits we're interested in- Returns:
- the selected bits, shifted right appropriately
- See Also:
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getValue
Obtains the value for the specified BitField, appropriately shifted right.Many users of a BitField will want to treat the specified bits as an int value, and will not want to be aware that the value is stored as a BitField (and so shifted left so many bits).
- Parameters:
holder- the int data containing the bits we're interested in- Returns:
- the selected bits, shifted right appropriately
- See Also:
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isAllSet
Returns whether all of the bits are set or not.This is a stricter test than
isSet(int), in that all of the bits in a multi-bit set must be set for this method to returntrue.- Parameters:
holder- the int data containing the bits we're interested in- Returns:
trueif all of the bits are set, elsefalse
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isSet
Returns whether the field is set or not.This is most commonly used for a single-bit field, which is often used to represent a boolean value; the results of using it for a multi-bit field is to determine whether *any* of its bits are set.
- Parameters:
holder- the int data containing the bits we're interested in- Returns:
trueif any of the bits are set, elsefalse
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set
Sets the bits.- Parameters:
holder- the int data containing the bits we're interested in- Returns:
- the value of holder with the specified bits set
to
1
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setBoolean
Sets a boolean BitField.- Parameters:
holder- the int data containing the bits we're interested inflag- indicating whether to set or clear the bits- Returns:
- the value of holder with the specified bits set or cleared
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setByte
Sets the bits.- Parameters:
holder- the byte data containing the bits we're interested in- Returns:
- the value of holder with the specified bits set
to
1
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setByteBoolean
Sets a boolean BitField.- Parameters:
holder- the byte data containing the bits we're interested inflag- indicating whether to set or clear the bits- Returns:
- the value of holder with the specified bits set or cleared
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setShort
Sets the bits.- Parameters:
holder- the short data containing the bits we're interested in- Returns:
- the value of holder with the specified bits set
to
1
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setShortBoolean
Sets a boolean BitField.- Parameters:
holder- the short data containing the bits we're interested inflag- indicating whether to set or clear the bits- Returns:
- the value of holder with the specified bits set or cleared
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setShortValue
Replaces the bits with new values.- Parameters:
holder- the short data containing the bits we're interested invalue- the new value for the specified bits- Returns:
- the value of holder with the bits from the value parameter replacing the old bits
- See Also:
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setValue
Replaces the bits with new values.- Parameters:
holder- the int data containing the bits we're interested invalue- the new value for the specified bits- Returns:
- the value of holder with the bits from the value parameter replacing the old bits
- See Also:
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