Question

如何用java程序利用二维数组创建一个矩阵,编写方法完成该矩阵的逆转,两个矩阵之和。

Answer 1

两个类,一个是矩阵对象类Matrix,另一个是测试类MatrixTest
可以实现矩阵创建,赋值,转置,加法,支持行列数不同的矩阵
注1,转置方法将输出一个新的矩阵,并不改变原有矩阵的内容
注2:加法方法是a.add(b),b不发生变化,a发生变化,加法将改变a矩阵的内容,不会产生新矩阵

public class Matrix {
private int rows;
private int columns;
private Integer[][] m;

// 行列构造法
public Matrix(int rows, int columns) {
this.rows = rows;
this.columns = columns;
this.m = new Integer[rows][columns];
}

// 二维数组构造法
public Matrix(Integer[][] m) {
this.m = m;
this.rows = m.length;
this.columns = m[0].length;
}

// 转置
public Matrix exchange() {
Integer[][] result = new Integer[columns][rows];

for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
result[j][i] = m[i][j];
}
}

return new Matrix(result);
}

// 加法
public void add(Matrix obj) {
if (obj.getRows() != rows || obj.getColumns() != columns) {
System.out.println("不同行列的矩阵不能相加");
} else {
Integer[][] objarray = obj.toArray();

for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
m[i][j] += objarray[i][j];
}
}
}
}

// 矩阵赋值
public void setValue(int row, int column, int value) {
if (row < rows && column < columns) {
m[row][column] = value;
} else {
System.out.println("索引超出边界");
}
}

public int getRows() {
return rows;
}

public int getColumns() {
return columns;
}

public Integer[][] toArray() {
return m;
}

public String toString() {
String result = "";

for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
result = result + m[i][j] + " ";
}

result += "\r\n";
}

return result;
}
}

public class MatrixTest {

public static void main(String[] args) {
Matrix m1 = new Matrix(2, 3);

for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
m1.setValue(i, j, i + j);
}
}

System.out.println(m1.toString());

System.out.println(m1.exchange().toString());

Matrix m2 = new Matrix(2, 3);

for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
m2.setValue(i, j, (i + 1) * (j + 1));
}
}

System.out.println(m2.toString());

m1.add(m2);

System.out.println(m1.toString());
}
}

Answer 2

1 2 3 3 2 1 4 4 4
4 5 6 + 6 5 4 = 10 10 10
7 8 9 9 8 7 16 16 16

这样吗？你说的逆转是什么意思？举个例子出来。

追问

1 2 3 1 4 7
4 5 6 变为 2 5 8
7 8 9 3 6 9
就是逆转

追答

代码如下。
----------------------------------------------------------------------------------------------------------------
public class Main {
public static void main(String[] args) {
int len = 3, index = 1;
int[][] a = new int[len][len], b = new int[len][len], c = new int[len][len];

for (int row = 0; row < len; row++) {
for (int col = 0; col < len; col++) {
a[row][col] = index++;
}
}

for (int row = 0; row < len; row++) {
for (int col = 0; col < len; col++) {
b[col][row] = a[row][col];
}
}

for (int row = 0; row < len; row++) {
for (int col = 0; col < len; col++) {
c[row][col] = a[row][col] + b[row][col];
}
}

System.out.println("A");

for (int row = 0; row < len; row++) {
for (int col = 0; col < len; col++) {
System.out.print(a[row][col] + "\t");
}
System.out.println();
}
System.out.println("B");
for (int row = 0; row < len; row++) {
for (int col = 0; col < len; col++) {
System.out.print(b[row][col] + "\t");
}
System.out.println();
}
System.out.println("C=A+B");
for (int row = 0; row < len; row++) {
for (int col = 0; col < len; col++) {
System.out.print(c[row][col] + "\t");
}
System.out.println();
}
}
}