实战Android：图片处理之ColorMatrix和Matrix实例

原博文在此，原来的文章中对Matrix和ColorMatrix都有解释，不再多说。

https://blog.csdn.net/qqxiaoqiang1573/article/details/50781466

https://blog.csdn.net/QQxiaoqiang1573/article/details/50847587

看一下效果，

原文的源码我整合到一个项目中，有些显示地方作了改动，下载即可直接运行。

https://download.csdn.net/download/tanmx219/10574162

 

下面是来自Android 官网，因为不想老是FQ，所以拷贝过来Ref.

https://developer.android.com/reference/android/graphics/Matrix

https://developer.android.com/reference/android/graphics/ColorMatrix

ColorMatrix

4x5 matrix for transforming the color and alpha components of a Bitmap. The matrix can be passed as single array, and is treated as follows:

[ a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t ]

When applied to a color [R, G, B, A], the resulting color is computed as:

R’ = a*R + b*G + c*B + d*A + e;

G’ = f*R + g*G + h*B + i*A + j;

B’ = k*R + l*G + m*B + n*A + o;

A’ = p*R + q*G + r*B + s*A + t;

That resulting color [R’, G’, B’, A’] then has each channel clamped to the 0 to 255 range.

The sample ColorMatrix below inverts incoming colors by scaling each channel by -1, and then shifting the result up by255 to remain in the standard color space.

[ -1, 0, 0, 0, 255, 0, -1, 0, 0, 255, 0, 0, -1, 0, 255, 0, 0, 0, 1, 0 ]

Summary

Public constructors

ColorMatrix()

Create a new colormatrix initialized to identity (as if reset() had been called).

ColorMatrix(float[] src)

Create a new colormatrix initialized with the specified array of values.

ColorMatrix(ColorMatrix src)

Create a new colormatrix initialized with the specified colormatrix.

Public methods
boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
final float[]	getArray() Return the array of floats representing this colormatrix.
void	postConcat(ColorMatrix postmatrix) Concat this colormatrix with the specified postmatrix.
void	preConcat(ColorMatrix prematrix) Concat this colormatrix with the specified prematrix.
void	reset() Set this colormatrix to identity: [ 1 0 0 0 0 - red vector 0 1 0 0 0 - green vector 0 0 1 0 0 - blue vector 0 0 0 1 0 ] - alpha vector
void	set(float[] src) Assign the array of floats into this matrix, copying all of its values.
void	set(ColorMatrix src) Assign the src colormatrix into this matrix, copying all of its values.
void	setConcat(ColorMatrix matA, ColorMatrix matB) Set this colormatrix to the concatenation of the two specified colormatrices, such that the resulting colormatrix has the same effect as applying matB and then applying matA.
void	setRGB2YUV() Set the matrix to convert RGB to YUV
void	setRotate(int axis, float degrees) Set the rotation on a color axis by the specified values.
void	setSaturation(float sat) Set the matrix to affect the saturation of colors.
void	setScale(float rScale, float gScale, float bScale, float aScale) Set this colormatrix to scale by the specified values.
void	setYUV2RGB() Set the matrix to convert from YUV to RGB

Public methods

equals

public boolean equals (Object obj)

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only ify.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z)returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

Parameters
obj	Object: the reference object with which to compare.

Returns
boolean	true if this object is the same as the obj argument; false otherwise.

getArray

public final float[] getArray ()

Return the array of floats representing this colormatrix.

 

Returns
float[]

postConcat

public void postConcat (ColorMatrix postmatrix)

Concat this colormatrix with the specified postmatrix.

This is logically the same as calling setConcat(postmatrix, this);

 

 

Parameters
postmatrix	ColorMatrix

preConcat

public void preConcat (ColorMatrix prematrix)

Concat this colormatrix with the specified prematrix.

This is logically the same as calling setConcat(this, prematrix);

 

 

Parameters
prematrix	ColorMatrix

reset

public void reset ()

Set this colormatrix to identity:

[ 1 0 0 0 0 - red vector 0 1 0 0 0 - green vector 0 0 1 0 0 - blue vector 0 0 0 1 0 ] - alpha vector

 

 

set

public void set (float[] src)

Assign the array of floats into this matrix, copying all of its values.

 

Parameters
src	float

set

public void set (ColorMatrix src)

Assign the src colormatrix into this matrix, copying all of its values.

 

Parameters
src	ColorMatrix

setConcat

public void setConcat (ColorMatrix matA, ColorMatrix matB)

Set this colormatrix to the concatenation of the two specified colormatrices, such that the resulting colormatrix has the same effect as applying matB and then applying matA.

It is legal for either matA or matB to be the same colormatrix as this.

 

 

Parameters
matA	ColorMatrix
matB	ColorMatrix

setRGB2YUV

public void setRGB2YUV ()

Set the matrix to convert RGB to YUV

 

setRotate

public void setRotate (int axis, float degrees)

Set the rotation on a color axis by the specified values.

axis=0 correspond to a rotation around the RED color axis=1 correspond to a rotation around the GREEN coloraxis=2 correspond to a rotation around the BLUE color

 

 

Parameters
axis	int
degrees	float

setSaturation

public void setSaturation (float sat)

Set the matrix to affect the saturation of colors.

 

Parameters
sat	float: A value of 0 maps the color to gray-scale. 1 is identity.

setScale

public void setScale (float rScale, float gScale, float bScale, float aScale)

Set this colormatrix to scale by the specified values.

 

Parameters
rScale	float
gScale	float
bScale	float
aScale	float

setYUV2RGB

public void setYUV2RGB ()

Set the matrix to convert from YUV to RGB

 

Matrix

java.lang.Object
↳	android.graphics.Matrix

 

The Matrix class holds a 3x3 matrix for transforming coordinates.

Summary

Nested classes
enum	Matrix.ScaleToFit Controlls how the src rect should align into the dst rect for setRectToRect().

Constants
int	MPERSP_0
int	MPERSP_1
int	MPERSP_2
int	MSCALE_X
int	MSCALE_Y
int	MSKEW_X
int	MSKEW_Y
int	MTRANS_X
int	MTRANS_Y

Public constructors

Matrix()

Create an identity matrix

Matrix(Matrix src)

Create a matrix that is a (deep) copy of src

Public methods
boolean	equals(Object obj) Returns true iff obj is a Matrix and its values equal our values.
void	getValues(float[] values) Copy 9 values from the matrix into the array.
int	hashCode() Returns a hash code value for the object.
boolean	invert(Matrix inverse) If this matrix can be inverted, return true and if inverse is not null, set inverse to be the inverse of this matrix.
boolean	isAffine() Gets whether this matrix is affine.
boolean	isIdentity() Returns true if the matrix is identity.
void	mapPoints(float[] dst, int dstIndex, float[] src, int srcIndex, int pointCount) Apply this matrix to the array of 2D points specified by src, and write the transformed points into the array of points specified by dst.
void	mapPoints(float[] dst, float[] src) Apply this matrix to the array of 2D points specified by src, and write the transformed points into the array of points specified by dst.
void	mapPoints(float[] pts) Apply this matrix to the array of 2D points, and write the transformed points back into the array
float	mapRadius(float radius) Return the mean radius of a circle after it has been mapped by this matrix.
boolean	mapRect(RectF rect) Apply this matrix to the rectangle, and write the transformed rectangle back into it.
boolean	mapRect(RectF dst, RectF src) Apply this matrix to the src rectangle, and write the transformed rectangle into dst.
void	mapVectors(float[] vecs) Apply this matrix to the array of 2D vectors, and write the transformed vectors back into the array.
void	mapVectors(float[] dst, int dstIndex, float[] src, int srcIndex, int vectorCount) Apply this matrix to the array of 2D vectors specified by src, and write the transformed vectors into the array of vectors specified by dst.
void	mapVectors(float[] dst, float[] src) Apply this matrix to the array of 2D vectors specified by src, and write the transformed vectors into the array of vectors specified by dst.
boolean	postConcat(Matrix other) Postconcats the matrix with the specified matrix.
boolean	postRotate(float degrees, float px, float py) Postconcats the matrix with the specified rotation.
boolean	postRotate(float degrees) Postconcats the matrix with the specified rotation.
boolean	postScale(float sx, float sy, float px, float py) Postconcats the matrix with the specified scale.
boolean	postScale(float sx, float sy) Postconcats the matrix with the specified scale.
boolean	postSkew(float kx, float ky) Postconcats the matrix with the specified skew.
boolean	postSkew(float kx, float ky, float px, float py) Postconcats the matrix with the specified skew.
boolean	postTranslate(float dx, float dy) Postconcats the matrix with the specified translation.
boolean	preConcat(Matrix other) Preconcats the matrix with the specified matrix.
boolean	preRotate(float degrees) Preconcats the matrix with the specified rotation.
boolean	preRotate(float degrees, float px, float py) Preconcats the matrix with the specified rotation.
boolean	preScale(float sx, float sy) Preconcats the matrix with the specified scale.
boolean	preScale(float sx, float sy, float px, float py) Preconcats the matrix with the specified scale.
boolean	preSkew(float kx, float ky) Preconcats the matrix with the specified skew.
boolean	preSkew(float kx, float ky, float px, float py) Preconcats the matrix with the specified skew.
boolean	preTranslate(float dx, float dy) Preconcats the matrix with the specified translation.
boolean	rectStaysRect() Returns true if will map a rectangle to another rectangle.
void	reset() Set the matrix to identity
void	set(Matrix src) (deep) copy the src matrix into this matrix.
boolean	setConcat(Matrix a, Matrix b) Set the matrix to the concatenation of the two specified matrices and return true.
boolean	setPolyToPoly(float[] src, int srcIndex, float[] dst, int dstIndex, int pointCount) Set the matrix such that the specified src points would map to the specified dst points.
boolean	setRectToRect(RectF src, RectF dst, Matrix.ScaleToFit stf) Set the matrix to the scale and translate values that map the source rectangle to the destination rectangle, returning true if the the result can be represented.
void	setRotate(float degrees, float px, float py) Set the matrix to rotate by the specified number of degrees, with a pivot point at (px, py).
void	setRotate(float degrees) Set the matrix to rotate about (0,0) by the specified number of degrees.
void	setScale(float sx, float sy) Set the matrix to scale by sx and sy.
void	setScale(float sx, float sy, float px, float py) Set the matrix to scale by sx and sy, with a pivot point at (px, py).
void	setSinCos(float sinValue, float cosValue, float px, float py) Set the matrix to rotate by the specified sine and cosine values, with a pivot point at (px, py).
void	setSinCos(float sinValue, float cosValue) Set the matrix to rotate by the specified sine and cosine values.
void	setSkew(float kx, float ky) Set the matrix to skew by sx and sy.
void	setSkew(float kx, float ky, float px, float py) Set the matrix to skew by sx and sy, with a pivot point at (px, py).
void	setTranslate(float dx, float dy) Set the matrix to translate by (dx, dy).
void	setValues(float[] values) Copy 9 values from the array into the matrix.
String	toShortString()
String	toString() Returns a string representation of the object.

 

Public methods

equals

public boolean equals (Object obj)

Returns true iff obj is a Matrix and its values equal our values.

 

Parameters
obj	Object: the reference object with which to compare.

Returns
boolean	true if this object is the same as the obj argument; false otherwise.

getValues

public void getValues (float[] values)

Copy 9 values from the matrix into the array.

 

Parameters
values	float

hashCode

public int hashCode ()

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equalscomparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java™ programming language.)

 

Returns
int	a hash code value for this object.

invert

public boolean invert (Matrix inverse)

If this matrix can be inverted, return true and if inverse is not null, set inverse to be the inverse of this matrix. If this matrix cannot be inverted, ignore inverse and return false.

 

Parameters
inverse	Matrix

Returns
boolean

isAffine

public boolean isAffine ()

Gets whether this matrix is affine. An affine matrix preserves straight lines and has no perspective.

 

Returns
boolean	Whether the matrix is affine.

isIdentity

public boolean isIdentity ()

Returns true if the matrix is identity. This maybe faster than testing if (getType() == 0)

 

Returns
boolean

mapPoints

public void mapPoints (float[] dst, int dstIndex, float[] src, int srcIndex, int pointCount)

Apply this matrix to the array of 2D points specified by src, and write the transformed points into the array of points specified by dst. The two arrays represent their "points" as pairs of floats [x, y].

 

Parameters
dst	float: The array of dst points (x,y pairs)
dstIndex	int: The index of the first [x,y] pair of dst floats
src	float: The array of src points (x,y pairs)
srcIndex	int: The index of the first [x,y] pair of src floats
pointCount	int: The number of points (x,y pairs) to transform

mapPoints

public void mapPoints (float[] dst, float[] src)

Apply this matrix to the array of 2D points specified by src, and write the transformed points into the array of points specified by dst. The two arrays represent their "points" as pairs of floats [x, y].

 

Parameters
dst	float: The array of dst points (x,y pairs)
src	float: The array of src points (x,y pairs)

mapPoints

public void mapPoints (float[] pts)

Apply this matrix to the array of 2D points, and write the transformed points back into the array

 

Parameters
pts	float: The array [x0, y0, x1, y1, ...] of points to transform.

mapRadius

public float mapRadius (float radius)

Return the mean radius of a circle after it has been mapped by this matrix. NOTE: in perspective this value assumes the circle has its center at the origin.

 

Parameters
radius	float

Returns
float

mapRect

public boolean mapRect (RectF rect)

Apply this matrix to the rectangle, and write the transformed rectangle back into it. This is accomplished by transforming the 4 corners of rect, and then setting it to the bounds of those points

 

Parameters
rect	RectF: The rectangle to transform.

Returns
boolean	the result of calling rectStaysRect()

mapRect

public boolean mapRect (RectF dst, RectF src)

Apply this matrix to the src rectangle, and write the transformed rectangle into dst. This is accomplished by transforming the 4 corners of src, and then setting dst to the bounds of those points.

 

Parameters
dst	RectF: Where the transformed rectangle is written.
src	RectF: The original rectangle to be transformed.

Returns
boolean	the result of calling rectStaysRect()

mapVectors

public void mapVectors (float[] vecs)

Apply this matrix to the array of 2D vectors, and write the transformed vectors back into the array. Note: this method does not apply the translation associated with the matrix. Use mapPoints(float[]) if you want the translation to be applied.

 

Parameters
vecs	float: The array [x0, y0, x1, y1, ...] of vectors to transform.

mapVectors

public void mapVectors (float[] dst, int dstIndex, float[] src, int srcIndex, int vectorCount)

Apply this matrix to the array of 2D vectors specified by src, and write the transformed vectors into the array of vectors specified by dst. The two arrays represent their "vectors" as pairs of floats [x, y]. Note: this method does not apply the translation associated with the matrix. Use mapPoints(float[], int, float[], int, int) if you want the translation to be applied.

 

Parameters
dst	float: The array of dst vectors (x,y pairs)
dstIndex	int: The index of the first [x,y] pair of dst floats
src	float: The array of src vectors (x,y pairs)
srcIndex	int: The index of the first [x,y] pair of src floats
vectorCount	int: The number of vectors (x,y pairs) to transform

mapVectors

public void mapVectors (float[] dst, float[] src)

Apply this matrix to the array of 2D vectors specified by src, and write the transformed vectors into the array of vectors specified by dst. The two arrays represent their "vectors" as pairs of floats [x, y]. Note: this method does not apply the translation associated with the matrix. Use mapPoints(float[], float[]) if you want the translation to be applied.

 

Parameters
dst	float: The array of dst vectors (x,y pairs)
src	float: The array of src vectors (x,y pairs)

postConcat

public boolean postConcat (Matrix other)

Postconcats the matrix with the specified matrix. M' = other * M

 

Parameters
other	Matrix

Returns
boolean

postRotate

public boolean postRotate (float degrees, float px, float py)

Postconcats the matrix with the specified rotation. M' = R(degrees, px, py) * M

 

Parameters
degrees	float
px	float
py	float

Returns
boolean

postRotate

public boolean postRotate (float degrees)

Postconcats the matrix with the specified rotation. M' = R(degrees) * M

 

Parameters
degrees	float

Returns
boolean

postScale

public boolean postScale (float sx, float sy, float px, float py)

Postconcats the matrix with the specified scale. M' = S(sx, sy, px, py) * M

 

Parameters
sx	float
sy	float
px	float
py	float

Returns
boolean

postScale

public boolean postScale (float sx, float sy)

Postconcats the matrix with the specified scale. M' = S(sx, sy) * M

 

Parameters
sx	float
sy	float

Returns
boolean

postSkew

public boolean postSkew (float kx, float ky)

Postconcats the matrix with the specified skew. M' = K(kx, ky) * M

 

Parameters
kx	float
ky	float

Returns
boolean

postSkew

public boolean postSkew (float kx, float ky, float px, float py)

Postconcats the matrix with the specified skew. M' = K(kx, ky, px, py) * M

 

Parameters
kx	float
ky	float
px	float
py	float

Returns
boolean

postTranslate

public boolean postTranslate (float dx, float dy)

Postconcats the matrix with the specified translation. M' = T(dx, dy) * M

 

Parameters
dx	float
dy	float

Returns
boolean

preConcat

public boolean preConcat (Matrix other)

Preconcats the matrix with the specified matrix. M' = M * other

 

Parameters
other	Matrix

Returns
boolean

preRotate

public boolean preRotate (float degrees)

Preconcats the matrix with the specified rotation. M' = M * R(degrees)

 

Parameters
degrees	float

Returns
boolean

preRotate

public boolean preRotate (float degrees, float px, float py)

Preconcats the matrix with the specified rotation. M' = M * R(degrees, px, py)

 

Parameters
degrees	float
px	float
py	float

Returns
boolean

preScale

public boolean preScale (float sx, float sy)

Preconcats the matrix with the specified scale. M' = M * S(sx, sy)

 

Parameters
sx	float
sy	float

Returns
boolean

preScale

public boolean preScale (float sx, float sy, float px, float py)

Preconcats the matrix with the specified scale. M' = M * S(sx, sy, px, py)

 

Parameters
sx	float
sy	float
px	float
py	float

Returns
boolean

preSkew

public boolean preSkew (float kx, float ky)

Preconcats the matrix with the specified skew. M' = M * K(kx, ky)

 

Parameters
kx	float
ky	float

Returns
boolean

preSkew

public boolean preSkew (float kx, float ky, float px, float py)

Preconcats the matrix with the specified skew. M' = M * K(kx, ky, px, py)

 

Parameters
kx	float
ky	float
px	float
py	float

Returns
boolean

preTranslate

public boolean preTranslate (float dx, float dy)

Preconcats the matrix with the specified translation. M' = M * T(dx, dy)

 

Parameters
dx	float
dy	float

Returns
boolean

rectStaysRect

public boolean rectStaysRect ()

Returns true if will map a rectangle to another rectangle. This can be true if the matrix is identity, scale-only, or rotates a multiple of 90 degrees.

 

Returns
boolean

reset

public void reset ()

Set the matrix to identity

 

set

public void set (Matrix src)

(deep) copy the src matrix into this matrix. If src is null, reset this matrix to the identity matrix.

 

Parameters
src	Matrix

setConcat

public boolean setConcat (Matrix a, Matrix b)

Set the matrix to the concatenation of the two specified matrices and return true.

Either of the two matrices may also be the target matrix, that is matrixA.setConcat(matrixA, matrixB); is valid.

In Build.VERSION_CODES.GINGERBREAD_MR1 and below, this function returns true only if the result can be represented. InBuild.VERSION_CODES.HONEYCOMB and above, it always returns true.

Parameters
a	Matrix
b	Matrix

Returns
boolean

setPolyToPoly

public boolean setPolyToPoly (float[] src, int srcIndex, float[] dst, int dstIndex, int pointCount)

Set the matrix such that the specified src points would map to the specified dst points. The "points" are represented as an array of floats, order [x0, y0, x1, y1, ...], where each "point" is 2 float values.

Parameters
src	float: The array of src [x,y] pairs (points)
srcIndex	int: Index of the first pair of src values
dst	float: The array of dst [x,y] pairs (points)
dstIndex	int: Index of the first pair of dst values
pointCount	int: The number of pairs/points to be used. Must be [0..4]

Returns
boolean	true if the matrix was set to the specified transformation

setRectToRect

public boolean setRectToRect (RectF src, RectF dst, Matrix.ScaleToFit stf)

Set the matrix to the scale and translate values that map the source rectangle to the destination rectangle, returning true if the the result can be represented.

Parameters
src	RectF: the source rectangle to map from.
dst	RectF: the destination rectangle to map to.
stf	Matrix.ScaleToFit: the ScaleToFit option

Returns
boolean	true if the matrix can be represented by the rectangle mapping.

setRotate

public void setRotate (float degrees, float px, float py)

Set the matrix to rotate by the specified number of degrees, with a pivot point at (px, py). The pivot point is the coordinate that should remain unchanged by the specified transformation.

Parameters
degrees	float
px	float
py	float

setRotate

public void setRotate (float degrees)

Set the matrix to rotate about (0,0) by the specified number of degrees.

Parameters
degrees	float

setScale

public void setScale (float sx, float sy)

Set the matrix to scale by sx and sy.

Parameters
sx	float
sy	float

setScale

public void setScale (float sx, float sy, float px, float py)

Set the matrix to scale by sx and sy, with a pivot point at (px, py). The pivot point is the coordinate that should remain unchanged by the specified transformation.

Parameters
sx	float
sy	float
px	float
py	float

setSinCos

public void setSinCos (float sinValue, float cosValue, float px, float py)

Set the matrix to rotate by the specified sine and cosine values, with a pivot point at (px, py). The pivot point is the coordinate that should remain unchanged by the specified transformation.

Parameters
sinValue	float
cosValue	float
px	float
py	float

setSinCos

public void setSinCos (float sinValue, float cosValue)

Set the matrix to rotate by the specified sine and cosine values.

 

Parameters
sinValue	float
cosValue	float

setSkew

public void setSkew (float kx, float ky)

Set the matrix to skew by sx and sy.

 

Parameters
kx	float
ky	float

setSkew

public void setSkew (float kx, float ky, float px, float py)

Set the matrix to skew by sx and sy, with a pivot point at (px, py). The pivot point is the coordinate that should remain unchanged by the specified transformation.

 

Parameters
kx	float
ky	float
px	float
py	float

setTranslate

public void setTranslate (float dx, float dy)

Set the matrix to translate by (dx, dy).

 

Parameters
dx	float
dy	float

setValues

public void setValues (float[] values)

Copy 9 values from the array into the matrix. Depending on the implementation of Matrix, these may be transformed into 16.16 integers in the Matrix, such that a subsequent call to getValues() will not yield exactly the same values.

Parameters
values	float

toShortString

public String toShortString ()

Returns
String

toString

public String toString ()

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())