在 Java 中使用构造函数的用户定义异常
在 Java 中，我们已经定义了异常类，比如 ArithmeticException、NullPointerException 等。这些异常已经被设置为在预定义的条件下触发，例如当您将一个数除以零时，它会触发算术异常。
在 Java 中，我们可以创建自己的异常类，并使用 throw 关键字抛出该异常。这些异常被称为用户自定义或自定义异常。
问题陈述:实现一个 Java 类 Matrix 来表示实数的二维矩阵。该类应该导出以下方法:
- 矩阵(int n，int m): 创建大小为 nxm 的矩阵的构造函数，所有值初始设置为 0；
- 矩阵乘积(矩阵 m): 如果两个矩阵具有相容的维数，则返回作为对象和 m 的乘积的矩阵，否则为空；异常错误矩阵维度如果矩阵的维度对于矩阵的乘法是错误的，则在方法 check()中抛出。
示例:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to create user defined
// exceptions
import java.util.Scanner;
// User defined exception class to store the exception
// message
class ExceptionWrongMatrixDimension extends Exception {
public ExceptionWrongMatrixDimension(String str)
{
// stores the exception message to be displayed
super(str);
}
}
class twoDimensionalMatrix {
void Matrix(int n, int m)
throws ExceptionWrongMatrixDimension
{
// initialize matrix to be processed
int[][] matrix = { { 1, 2 },
{
4,
5,
} };
System.out.println("\nMatrix is :");
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println();
}
int rows = 2;
int cols = 2;
if (n != rows) {
// throw keyword for an exception in a method
throw new ExceptionWrongMatrixDimension(
"Invalid matrix dimensions to multiply");
}
else {
int[][] m_matrix = { { 6, 3 },
{
9,
2,
} };
System.out.println("\nMatrix to multiply is :");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
System.out.print(m_matrix[i][j] + " ");
}
System.out.println();
}
System.out.println("\nMatrix to multiply is :");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
System.out.print(m_matrix[i][j] + " ");
}
System.out.println();
}
int c[][] = new int[m][n];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < rows; j++) {
c[i][j] = 0;
for (int k = 0; k < rows; k++) {
c[i][j] += matrix[i][j]
* m_matrix[k][j];
}
}
}
System.out.println(
"\n\nMatrix after multiplication is");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
// prints the third matrix containing
// the multiplied values
System.out.print(c[i][j] + " ");
}
System.out.println();
}
}
}
}
public class Main {
public static void main(String args[])
{
twoDimensionalMatrix matrix
= new twoDimensionalMatrix();
try {
// block of code to be tested for errors while
// it is being executed.
System.out.println("Enter the number of rows");
int n = 2;
System.out.println(
"Enter the number of columns");
int m = 2;
matrix.Matrix(n, m);
}
catch (ExceptionWrongMatrixDimension e) {
// block of code to be executed, if an error
// occurs in the try block.
System.out.println(
"ExceptionWrongMatrixDimension:");
// returns a method object. The name parameter
// is passed as a string.
System.out.println(e.getMessage());
}
}
}
Output
Enter the number of rows
Enter the number of columns
Matrix is :
1 2
4 5
Matrix to multiply is :
6 3
9 2
Matrix to multiply is :
6 3
9 2
Matrix after multiplication is
15 10
60 25
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