com.mathworks.toolbox.javabuilder.MWArray Class

Namespace: com.mathworks.toolbox.javabuilder

Java class to serve as base for all MATLAB array types with native array handling

Description

Declaration

public abstract class MWArray extends java.lang.Object 
implements java.lang.Cloneable, java.lang.Comparable, java.io.Serializable, Disposable

The MWArray class is the base class for all MATLAB array types. This class stores a handle to a native MATLAB array and provides methods for querying the array's properties and accessing the array's data

Implemented Interfaces: Disposable, java.io.Serializable, java.lang.Cloneable, java.lang.Comparable

Direct Known Subclasses: MWCellArray, MWCharArray, MWJavaObjectRef, MWLogicalArray, MWMatrixRef, MWNumericArray, MWStringArray, MWStructArray

Class Attributes: ,

Creation

Constructors

public MWArray()

Properties

Public Properties

EMPTY_ARRAY — Represent an empty array

public static final MWArray

A convenient, efficient, and consistent way to represent an empty array as follows:

public static final MWArray EMPTY_ARRAY

Methods

Public Methods

applyVisitor	public abstract <T> T applyVisitor(AbstractMWArrayVisitor<T> v) This method is abstract and returns a type specified by the type parameter <T>. It takes an instance of AbstractMWArrayVisitor<T> as an argument. The purpose of this method is to apply the visitor pattern to an MWArray object. By calling this method with an appropriate visitor, you can traverse and perform operations on elements of the MWArray in a type-safe manner. Parameters: v An instance of AbstractMWArrayVisitor<T> representing the visitor to be applied to the MWArray object. Returns: T The result of applying the visitor to the MWArray object, with the specific type specified by <T>.
classID	public abstract MWClassID classID() Returns the MATLAB type of this array. This example uses a 3-by-6 MWNumericArray object A, as constructed by this Java code: int[][] Adata = {{ 1, 2, 3, 4, 5, 6}, { 7, 8, 9, 10, 11, 12}, {13, 14, 15, 16, 17, 18}}; MWNumericArray A = new MWNumericArray(Adata, MWClassID.INT32); Example: Getting the Class ID of an MWArray Return the class ID for an MWNumericArray object created previously as follows: System.out.println("Class of A is " + A.classID()); Class of A is int32 Returns: MWClassID of this array
clone	public java.lang.Object clone() throws java.lang.CloneNotSupportedException This method creates and returns a deep copy of the MWArray object. Because clone allocates a new array, any changes made to this new array are not reflected in the original. Example: Cloning an MWArray Object Object C = A.clone(); System.out.println("Clone of matrix A is:"); System.out.println(C.toString()); Clone of matrix A is: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Overrides: clone in class java.lang.Object Returns: An MWArray instance representing a deep copy of the underlying MATLAB array. Throws: java.lang.CloneNotSupportedException The object's class does not implement the Cloneable interface.
columnIndex	public abstract int[] columnIndex() This method returns an array containing the column index of each element in the underlying MATLAB array. In the following example, the contents of the sparse MWArray (created by the newSparse method) are: (2,1) 50 (1,2) 10 (2,2) 60 (1,5) 40 (2,5) 90 Example: Getting the Column Indices of a Sparse MWArray Get the column indices of the elements of the sparse array: System.out.print("Column indices are: "); int[] colidx = A.columnIndex(); for (int i = 0; i < 5; i++) System.out.print(colidx[i] + " "); System.out.println(); When run, the example displays this output: Column indices are: 1 2 2 5 5 Returns: Array of indices.
compareTo	public abstract int compareTo(java.lang.Object obj) This method compares the MWArray object with the input object. It returns a negative integer, zero, or a positive integer if the MWArray object is less than, equal to, or greater than the specified object, respectively. Example: Comparing MWArrays with compareTo Create a shared copy of the MWArray object and then compare it to the original object. A return value of zero indicates that the two objects are equal: Object S = A.sharedCopy(); if (A.compareTo(S) == 0) System.out.println("Matrix S is equal to matrix A"); Matrix S is equal to matrix A Specified by: compareTo in interface java.lang.Comparable Parameters: obj Object Array to compare with this MWArray object
dispose	public abstract void dispose() This method destroys the native MATLAB array contained by the array object and frees the memory occupied by the array. Example: Constructing an MWArray Object Construct and then destroy an MWArray object as follows: MWArray A = new MWArray(); A.dispose(); Specified by: dispose in interface Disposable
disposeArray	public static void disposeArray(java.lang.Object obj) This method destroys any native MATLAB arrays contained in the input object and frees the memory occupied by them. This is a static method of the class and thus does not need to be invoked in reference to an instance of the class. If the input object implements the Disposable interface, the object is freed by calling its Disposable.dispose() method. If the input object represents an array of Disposable instances, each object in the array is disposed. If the input object represents an array of java.lang.Object, or a multi-dimensional array, the array is recursively processed to free each Disposable instance contained in the array. Example: Constructing an MWNumericArray Object MWArray[] MArr = new MWArray[10]; for (int i = 0; i < 10; i++) MArr[i] = new MWNumericArray(); MWArray.disposeArray(MArr); Parameters: obj Object to process.
equals	public abstract boolean equals(java.lang.Object obj) This method indicates the MWArray object is equal to the input object. The equals method of the MWArray class overrides the equals method of class Object. Example: Comparing MWArrays with equals Object S = A.sharedCopy(); if (A.equals(S)) System.out.println("Matrix S is equal to matrix A"); Matrix S is equal to matrix A Overrides: equals in class java.lang.Object Parameters: obj Object Array to compare with this MWArray object
get	public abstract java.lang.Object get(int index) Returns the element at the specified 1-based offset in this array. Offers better performance than public Object get(int[] index). Example: Getting an MWArray Value with get int[] cdims = {1, 3}; MWArray C = new MWArray(cdims); Integer val = new Integer(15); int[] index2 = {1, 3}; C.set(index2, val); Object x = C.get(index2); if (x instanceof int[][]) { int[][] y = (int[][])x; System.out.println("B: Cell data C(1,3) is " + y[0][0]); } B: Cell data C(1,3) is 15 Parameters: index The index of the requested element. Valid range: 1 <= index <= N, where N = total number of elements in the array. Returns: Object containing the requested element. Throws: java.lang.IndexOutOfBoundsException An invalid index has been supplied.
get	public abstract java.lang.Object get(int[] index) Returns the element at the specified 1-based index-array in this array. Parameters: index Array of indices specifying the location of the requested element. The length of the index array must be exactly the number of dimensions of this array. Each element of the index array has the valid range: 1 <= index[i] <= N[i], where N[i] = the size of the ith dimension. Returns: Object containing the requested element. Throws: java.lang.IndexOutOfBoundsException An invalid index has been supplied.
getData	public abstract java.lang.Object getData() Returns a 1-D array containing a copy of the data in the underlying MATLAB array. The elements of the returned array are converted according to default conversion rules. If the underlying MATLAB array is a complex numeric type, getData returns the real part. If the underlying array is a cell or struct array, toArray is recursively called on each cell. Example: Getting an MWArray Value with getData Get the data from MWArray object A, casting the type from Object to int: System.out.println("Data read from matrix A:"); int[] x = (int[]) A.getData(); for (int i = 0; i < x.length; i++) System.out.print(" " + x[i]); System.out.println(); Data read from matrix A: 1 7 13 2 8 14 3 9 15 4 10 16 5 11 17 6 12 18 Returns: A 1-D array of elements stored in column-wise order. The length of the returned array equals numberOfElements() for a non-sparse array, and numberOfNonZeros() for a sparse array.
getDimensions	public abstract int[] getDimensions() Returns an array containing the size of each dimension of this array. This example uses a 3-by-6 MWNumericArray object A, as constructed by this Java code: int[][] Adata = {{ 1, 2, 3, 4, 5, 6}, { 7, 8, 9, 10, 11, 12}, {13, 14, 15, 16, 17, 18}}; MWNumericArray A = new MWNumericArray(Adata, MWClassID.INT32); Example: Getting Array Dimensions of an MWArray int[] dimA = A.getDimensions(); System.out.println("Dimensions of A are " + dimA[0] + " x " + dimA[1]); Dimensions of A are 3 x 6 Returns: array containing size of each dimension
hashCode	public abstract int hashCode() This method returns a hash code value for the MWArray object. The hashCode method of the MWArray class overrides the hashCode method of class Object. Example: Getting an MWArray Hash Code Obtain the hash code for MWArray object A: System.out.println("Hash code for matrix A is " + A.hashCode()); Hash code for matrix A is 45668 Overrides: hashCode in class java.lang.Object
isEmpty	public abstract boolean isEmpty() This method returns true if the array object contains no elements, and false otherwise. This example uses a 3-by-6 MWNumericArray object A, as constructed by this Java code: int[][] Adata = {{ 1, 2, 3, 4, 5, 6}, { 7, 8, 9, 10, 11, 12}, {13, 14, 15, 16, 17, 18}}; MWNumericArray A = new MWNumericArray(Adata, MWClassID.INT32); Example: Testing for an Empty MWArray if (A.isEmpty()) System.out.println("Matrix A is empty"); else System.out.println("A = " + A.toString()); A= 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Returns: true if empty, false otherwise.
isSparse	public abstract boolean isSparse() This method returns true if the MWArray object is sparse, and false otherwise. The contents of the sparse MWArray, created by the newSparse method, used in the following example are: (2,1) 50 (1,2) 10 (2,2) 60 (1,5) 40 (2,5) 90 Example: Testing an MWArray for Sparseness Test the MWArray object A created previously for sparseness: if (A.isSparse()) System.out.println("Matrix A is sparse"); Matrix A is sparse Returns: true if sparse, false otherwise
maximumNonZeros	public abstract int maximumNonZeros() This method returns the allocated capacity of a sparse array. If the underlying array is nonsparse, this method returns the same value as numberOfElements. The contents of the sparse MWArray, created by the newSparse method, used in the following example are: (2,1) 50 (1,2) 10 (2,2) 60 (1,5) 40 (2,5) 90 Example: Getting the Maximum Number of Nonzeros in an MWArray Display the maximum number of nonzeros for this array: System.out.println("Maximum number of nonzeros for matrix A is " + A.maximumNonZeros()); When run, the example displays this output: Maximum number of nonzeros for matrix A is 10
numberOfDimensions	public abstract int numberOfDimensions() Returns the number of dimensions of this array. This example uses a 3-by-6 MWNumericArray object A, as constructed by this Java code: int[][] Adata = {{ 1, 2, 3, 4, 5, 6}, { 7, 8, 9, 10, 11, 12}, {13, 14, 15, 16, 17, 18}}; MWNumericArray A = new MWNumericArray(Adata, MWClassID.INT32); Example: Getting the Number of Dimensions of an MWArray Display the number of elements in array object A: System.out.println("Matrix A has " + A.numberOfDimensions() + " dimensions"); When run, the example displays this output: Matrix A has 2 dimensions Returns: number of dimensions
numberOfElements	public abstract int numberOfElements() Returns the total number of elements in this array. This example uses a 3-by-6 MWNumericArray object A, as constructed by this Java code: int[][] Adata = {{ 1, 2, 3, 4, 5, 6}, { 7, 8, 9, 10, 11, 12}, {13, 14, 15, 16, 17, 18}}; MWNumericArray A = new MWNumericArray(Adata, MWClassID.INT32); Example: Getting the Number of MWArray Elements Display the number of elements in array object A: System.out.println("Matrix A has " + A.numberOfElements() + " elements"); When run, the example displays this output: Matrix A has 18 elements Returns: number of elements
numberOfNonZeros	public abstract int numberOfNonZeros() This method returns the number of nonzero elements in a sparse array. If the underlying array is nonsparse, this method returns the same value as numberOfElements. The contents of the sparse MWArray, created by the newSparse method, used in the following example are: (2,1) 50 (1,2) 10 (2,2) 60 (1,5) 40 (2,5) 90 Example: Getting the Number of Nonzeros in an MWArray Display the number of nonzero values in this array: When run, the example displays this output: System.out.println("The number of nonzeros for matrix A is " + A.numberOfNonZeros()); The number of nonzeros for matrix A is 5 Returns: Current number of non-zero elements in a sparse array.
rowIndex	public abstract int[] rowIndex() This method returns an array containing the row index of each element in the underlying MATLAB array. In the following example, the contents of the sparse MWArray (created by the newSparse method) are: (2,1) 50 (1,2) 10 (2,2) 60 (1,5) 40 (2,5) 90 Example: Getting the Row Indices of a Sparse MWArray Get the row indices of the elements of the sparse array: System.out.print("Row indices are: "); int[] rowidx = A.rowIndex(); for (int i = 0; i < 5; i++) System.out.print(rowidx[i] + " "); System.out.println(); Row indices are: 2 1 2 1 2 Returns: Array of indices.
set	public abstract void set(int index, java.lang.Object element) Replaces the element at the specified 1-based offset in this array with the specified element. Offers better performance than public void set(int[] index, Object element). Example: Setting an MWArray Value Modify the data in element (2, 4) of MWArray object A: int[] index = {2, 4}; A.set(index, 555); Object d_out = A.get(index); System.out.println("Data read from A(2,4) is " + d_out.toString()); Data read from A(2,4) is 555 Parameters: index The index of the element to replace. Valid range: 1 <= index <= N, where N = total number of elements in the array. element New element to replace at index. Throws: java.lang.IndexOutOfBoundsException An invalid index has been supplied.
set	public abstract void set(int[] index, java.lang.Object element) Replaces the element at the specified 1-based index-array in this array with the specified element. Parameters: index Array of indices specifying the location of the element to replace. The length of the index array must be exactly the number of dimensions of this array. Each element of the index array has the valid range: 1 <= index[i] <= N[i], where N[i] = the size of the ith dimension. element New element to replace at index. Throws: java.lang.IndexOutOfBoundsException An invalid index has been supplied.
setData	public abstract void setData(java.lang.Object data)
sharedCopy	public abstract java.lang.Object sharedCopy() This method creates and returns a shared copy of the array. The shared copy points to the underlying original MATLAB array. Any changes made to the copy are reflected in the original. Example: Making a Shared Copy of an MWArray Create a shared copy of MWArray object A: Object S = A.sharedCopy(); System.out.println("Shared copy of matrix A is:"); System.out.println(S.toString()); Shared copy of matrix A is: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Returns: An MWArray instance representing a shared copy of the underlying MATLAB array.
toArray	public abstract java.lang.Object[] toArray() Returns an array containing a copy of the data in the underlying MATLAB array. The returned array has the same dimensionality as the underlying MATLAB array. The elements of the returned array are converted according to default conversion rules. If the underlying MATLAB array is a complex numeric type, toArray returns the real part. If the underlying array is sparse, a full representation of the array is returned. Care should be taken when calling toArray on a sparse array with large row and column dimensions, as this action may exhaust system memory. If the underlying array is a cell or struct array, toArray is recursively called on each cell Example: Getting an MWArray with toArray Create and display a copy of MWArray object A: int[][] x = (int[][]) A.toArray(); int[] dimA = A.getDimensions(); System.out.println("Matrix A is:"); for (int i = 0; i < dimA[0]; i++) { for (int j = 0; j < dimA[1]; j++) System.out.print(" " + x[i][j]); System.out.println(); } Matrix A is: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Returns: An array with the same dimensionality of the MATLAB array.
toString	public abstract java.lang.String toString() This method returns a string representation of the array. The toString method of the MWArray class overrides the toString method of class Object. Example: Converting an MWArray to a String Display the contents of MWArray object A: System.out.println("A = " + A.toString()); When run, the example displays the contents of A: A= 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Overrides: toString in class java.lang.Object

Inherited Methods

Methods inherited from class java.lang.Object.

finalize	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
getClass	public final Class<?> getClass() Returns the runtime class of this Object.
notify	public final void notify()
notifyAll	public final void notifyAll() Wakes up all threads that are waiting on this object's monitor.
wait	public final void wait(long timeout, int nanos) throws InterruptedException Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.

Examples

Hello World

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Inheritance Hierarchy

• java.lang.Object

  • com.mathworks.javabuilder.MWArray

Version History

Introduced in R2006a