我想构建一个程序来操作多维数组，这是我想学习的一个新概念......
我想它可能有一些方法......
public int get(int row, int column)
// a method to get the value in row/column
// keep in mind columns/rows start at 0
public void set(int row, int column, int value)
// a method to set the matrix element to the value
// again keep in mind columns/rows start at 0
public void negate()
// method that negates through each element
public void add(Matrix m)
// adds the matrix m to this
谁能告诉我这是否是正确的方法，我该怎么做？提前致谢
您的方法看起来通常是明智的。
有几点需要考虑：
int对于数学矩阵的基本数据类型来说，这并不是一个好的选择。例如，您通常无法获得int矩阵的准确逆。你确定你宁愿不使用double吗？add，set和negate应该返回一个新的矩阵。支持可变性的唯一真正论据是性能（但在这种情况下......你应该使用现有的库而不是滚动你自己的库！）如果你想使用或研究一个现有的库来做这样的事情（以及更多），那么你可能会对我相当广泛的向量/矩阵数学库感兴趣：
Vectorz 专门针对double用于快速数值工作的原始数组，但同样的原则也适用于任何类型的数组/矩阵。
看看这个实现并分析它，如果这是为了家庭作业，那么如果你不知道发生了什么，那么“剪贴板继承”对你没有好处。
public class Matrix
{
private double[][] matrixData;
private int col;
private int row;
/**
* Create matrix of zero size
*/
public Matrix()
{
this(0);
}
public Matrix(double[][] matrixData)
{
this.matrixData = matrixData;
this.row = matrixData.length;
this.col = matrixData[0].length;
}
public Matrix(double[] matrixData)
{
this.row = matrixData.length;
for (int i = 0, size = matrixData.length; i < size; i++)
{
this.matrixData[0][i] = matrixData[i];
}
}
public Matrix(int size)
{
this.matrixData = new double[size][size];
this.col = size;
this.row = size;
}
public Matrix(int row, int col)
{
matrixData = new double[row][col];
this.row = row;
this.col = col;
}
/**
* Static method which creates a matrix with a single column.
*
* @param input
* @return
*/
public static Matrix createColumnMatrix(final double input[])
{
double result[][] = new double[input.length][1];
for (int i = 0; i < input.length; i++)
result[i][0] = input[i];
return new Matrix(result);
}
/**
* Static method which creates a matrix with a single row.
*
* @param input
* @return
*/
public static Matrix createRowMatrix(final double input[])
{
double result[][] = new double[1][input.length];
for (int i = 0, size = input.length; i < size; i++)
result[0][i] = input[i];
return new Matrix(result);
}
/**
* Convert the matrix into a one dimentional matrix
*
* @return
*/
public double[] toPackedArray()
{
int size = row * col;
int index = 0;
double[] results = new double[size];
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
results[index++] = matrixData[i][j];
return results;
}
/**
* Adds the specified value to given cell in the matrix.
*
* @param row
* @param col
* @param value
*/
public void add(final int row, final int col, final double value)
{
matrixData[row][col] += value;
}
/**
* Sets every cell in a matrix to zero.
*/
public void clear()
{
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
matrixData[i][j] = 0;
}
@Override
protected Object clone() throws CloneNotSupportedException
{
return new Matrix(matrixData);
}
@Override
public boolean equals(Object obj)
{
if (obj == null)
{
return false;
}
if (!(obj instanceof Matrix))
{
return false;
}
Matrix that = (Matrix)obj;
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
{
if (matrixData[i][j] != that.get(i,j))
return false;
}
return true;
}
public void print()
{
for (int i = 0; i < matrixData.length; i++)
{
for (int j = 0; j < matrixData[i].length; j++)
{
System.out.print(matrixData[i][j] + ", ");
}
System.out.println();
}
}
/**
* Gets one column of a matrix object as a new matrix object.
*
* @param col
* @return
*/
public Matrix getCol(final int col)
{
double[] results = new double[matrixData[col].length];
for (int i = 0; i < row; i++)
results[i] = matrixData[i][col];
return Matrix.createColumnMatrix(results);
}
/**
* Gets one row of a matrix object as a new matrix object.
*
* @param row
* @return
*/
public Matrix getRow(final int row)
{
double[] results = new double[this.row];
for (int i = 0; i < col; i++)
results[i] = matrixData[row][i];
return Matrix.createRowMatrix(results);
}
/**
* Returns the sum of every cell in a matrix object.
*
* @return
*/
public double sum()
{
double total = 0;
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
{
total += matrixData[i][j];
}
return total;
}
/**
* Determines if every cell in a matrix object is zero.
*
* @return
*/
public boolean isZero()
{
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
{
if (matrixData[i][j] != 0)
return false;
}
return true;
}
/**
* Get given value at a specific location
*
* @param row
* @param col
* @return
*/
public double get(int row, int col)
{
return matrixData[row][col];
}
public int getCols()
{
return col;
}
public int getRows()
{
return row;
}
public static Matrix identity(final int size)
{
final Matrix result = new Matrix(size,size);
for (int i = 0; i < size; i++)
{
result.set(i,i,1);
}
return result;
}
/**
* Set given row and column using 0 based indexes
*
* @param row
* @param col
* @param value
*/
public void set(int row, int col, double value)
{
matrixData[row][col] = value;
}
/**
* Get the copy of the current matrix
*
* @return
*/
public double[][] getRawMatrix()
{
double[][] copy = new double[matrixData.length][];
for (int i = 0; i < matrixData.length; i++)
{
copy[i] = new double[matrixData[i].length];
for (int j = 0; j < matrixData[i].length; j++)
copy[i][j] = matrixData[i][j];
}
return copy;
}
public static void dump(double[] arr)
{
for (int i = 0; i < arr.length; i++)
{
System.out.print(arr[i] + ", ");
}
}
public void dump()
{
dump(System.out);
}
public void dump(PrintStream ps)
{
for (int i = 0; i < row; i++)
{
for (int j = 0; j < col; j++)
{
ps.print(matrixData[i][j] + ", ");
}
ps.println();
}
ps.println();
}
public void add(Matrix contribution)
{
// TODO Auto-generated method stub
}
谁能告诉我这是否是正确的方法，我该怎么做？
是的，一点没错。
但是，按照惯例，注释应该在方法声明的上方。并称为方法头。
例如：
// a method to get the value in row/column
// keep in mind columns/rows start at 0
public int get(int row, int column)
您的界面（即您计划的方法）似乎非常合理。
至于一般的多维数组操作，有很多关于这方面的教程，例如here、here、here、here和here。
Aaand 让您开始使用简单的代码示例：
创建很棒的多维数组
int[][] multi = new int[2][3]; // this mda has two rows and three columns
访问他们的 rad 元素
int el = multi[0][1]; // el is in the first row, second column
像老板一样遍历它们
for (int rowNum = 0; rowNum < multi.length; rowNum++) {
for (int colNum = 0; colNum < multi[rowNum].length; colNum++) {
int currentElement = multi[rowNum][colNum];
}
}