将元素设置为行r和列c的值为v该方法必须检查r和c是否在nRow（）和nCol（）的范围内。如果r或c超出矩阵维度的范围，它就不应该做任何事情。
我明白他们在问我什么，但不确定我的代码在做什么是不正确的。
public class Matrix {
private int nRow, nCol;
private double[] data; // must store as linear array unless 0
// getter for NRow - do not modify
public int getNRow() {
return nRow;
}
// getter for NCol - do not modify
public int getNCol() {
return nCol;
}
/**
* set nRow to r if r is not negative, otherwise set nRow to 0
*
* @param r:
* value to be assigned to nRow
*/
public void setNRow(int r) {
if (r > 0)
nRow = r;
else
nRow = 0;
// to be completed
}
/**
* set nCol to c if c is not negative, otherwise set nCol to 0
*
* @param c:
* value to be assigned to nCol
*/
public void setNCol(int c) {
if (c > 0)
nCol = c;
else
nCol = 0;
// to be completed
}
/**
*
* @return true if numberOfRow() and numberOfColumn are zero
*/
public boolean isEmpty() {
if (nRow == 0)
if (nCol == 0)
return true;
return false;
// to be completed
}
/**
* DO NOT MODIFY if arr is null, instance array data should become null,
* otherwise if arr.length is not equal to nRow * nCol, set nRow, nCol to 0 and
* data to null, otherwise instantiate instance array data to be of the same
* size as arr. then copy each item of arr into data. IMPORTANT: do not
* re-declare data!
*
* @param arr
*/
public void setData(double[] arr) {
if (arr == null)
data = null;
else {
if (nRow * nCol != arr.length) {
nRow = 0;
nCol = 0;
data = null;
return;
}
data = new double[arr.length];
for (int i = 0; i < arr.length; i++) {
data[i] = arr[i];
}
}
}
/**
* Default constructor. instance variables nRow and nCol should be set to 0
* using the setters. the data member data should be set to null
*/
public Matrix() {
nRow = 0;
nCol = 0;
data = null;
// to be completed
}
/**
* Constructor a matrix which has r rows and c columns. data member nRow and
* nCol should be set accordingly using setters. AFTER THAT, instance array data
* should be instantiated to size nRow*nCol
*
* @param r:
* number of rows
* @param c:
* number of columns
*/
public Matrix(int r, int c) {
setNRow(r);
setNCol(c);
// to be completed
}
/**
*
* @return true if the matrix is a square matrix (a matrix for which number of
* rows and number of columns is the same)
*/
public boolean isSquare() {
if (nRow == nCol)
return true;
return false; // to be completed
}
/**
*
* @param other
* @return true if calling object and parameter object have the same dimensions
* (they both have the same number of rows compared to each other, and
* the same number of columns compared to each other), false otherwise
*/
public boolean sameDimensions(Matrix other) {
if (this.nRow == other.nRow)
return true;
return false; // to be completed
}
/**
* @param r
* @return true if r is a valid row number, false otherwise only row numbers 0
* to nRow-1 (inclusive on both sides) are valid
*/
public boolean isValidRowNumber(int r) {
if (r < 0 || r > nRow - 1)
return false;
return true; // to be completed
}
/**
* @param c
* @return true if c is a valid column number, false otherwise only column
* numbers 0 to nCol-1 (inclusive on both sides) are valid
*/
public boolean isValidColumnNumber(int c) {
if (c < 0 || c > nCol - 1)
return false;
return true; // to be completed
}
/**
* The constructor must first check that r * c is equal to the length of array
* d. if this requirement does not meet, member nRow and nCol should be set to 0
* and data should be set to null. if the requirement is met, nRow should be set
* to r and nCol should be set to c. d should be copied into data using
* setData(double[] arr) method
*
* @param r:
* number of rows
* @param c:
* number of columns
* @param d:
* array d to populate data
*/
public Matrix(int r, int c, double[] d) {
if (r * c == d.length) {
nRow = r;
nCol = c;
setData(d);
} else {
nRow = 0;
nCol = 0;
data = null;
}
}
/**
* The method must check that r and c are valid row numbers and column numbers
* respectively. Note that row and column numbers begin with 0. It should return
* 0 if r or c is out of range of the dimension of the matrix
*
* @param r
* @param c
* @return an element of the Matrix at row r and column c
*/
public double get(int r, int c) {
if (isValidRowNumber(r) && isValidColumnNumber(c))
return data[(r * nCol) + c];
return 0; // to be completed
}
/**
* setting and element to row r and column c with value v The method must check
* that r and c are in the range of numberOfRow() and numberOfColumn(). It
* should not do anything if r or c is out of range of the dimension of the
* matrix
*
* @param r
* @param c
* @param v
*/
public void set(int r, int c, double v) {
if(r >= 0 && r <= nRow - 1 && (c >= 0) && c<=nCol - 1)
data[(r * nCol) + c] = v;
// to be completed
}
/**
* DO NOT MODDIFY
*/
public String toString() {
String result = "";
for (int r = 0; r < nRow; r++) {
result = result + "| ";
for (int c = 0; c < nCol; c++) {
result = result + String.format("%7.2f ", get(r, c));
}
result = result + "|\n";
}
return result;
}
}
提前致谢
Matrix m = new Matrix(2, 3);
for(int r = 0; r < 2; r++)
{
for(int c = 0; c < 3; c++)
{
assertEquals(0, m.get(r, c), 0.01); //before TEST FAILED HERE
m.set(r, c, (r+1)*(c+1));
assertEquals((r+1)*(c+1), m.get(r, c), 0.01); //after
}
}