我需要创建代码，该代码接受用户输入来创建 2d 数组的大小（行和列必须小于 6），然后用用户给出的值填充它（介于 -10 和 10 之间）。我获取值的循环根本不起作用，我不确定为什么。这是代码
import java.util.Scanner;
public class Matrix {
public static void main(String[] args) {
// TODO Auto-generated method stub
// Implement scanner
Scanner input = new Scanner(System.in);
// create loop for accepting matrix input
// first accept row size
System.out.println("Please enter the number of rows in your matrix. Must be 5 or less.");
int row = input.nextInt();
while (row > 5 || row < 1) {
System.out.println("Sorry. Your number is not the correct size. "
+ "Please enter the number of rows in your matrix. Must be between 5 and 1.");
row = input.nextInt();
}
// next accept column size
System.out.println("Please enter the number of columns in your matrix. Must be 5 or less.");
int column = input.nextInt();
while (column > 5 || column < 1) {
System.out.println("Sorry. Your number is not the correct size. "
+ "Please enter the number of columns in your matrix. Must be between 5 and 1.");
column = input.nextInt();
}
// declare array with row and columns the user gave
int[][] userArray = new int[row][column];
// create loop for accepting values within the matrix
// first loop for row values
for (int i = 0; i < userArray.length; i++) {
System.out.println("Please enter numbers between -10 and 10 for your matrix rows");
int rowValues = input.nextInt();
while (rowValues > 10 || column < -10) {
System.out.println(
"Sorry. Your number is not the correct size. " + "Please enter a number between 10 and -10.");
rowValues = input.nextInt();
}
// second embedded loop for column values
for (int j = 0; j < userArray[i].length; j++) {
System.out.println("Please enter numbers between -10 and 10 for your matrix columns");
int columnValues = input.nextInt();
while (columnValues > 10 || column < -10) {
System.out.println("Sorry. Your number is not the correct size. "
+ "Please enter a number between 10 and -10.");
columnValues = input.nextInt();
}
}
}
printMatrix(userArray);
}
这里有几件事。首先，for-loop有两个单独的行和列循环。我假设您要做的是提示用户输入 2D 数组的每个单独单元格，这将需要两个嵌套循环。其次，您的代码示例绝不会将用户输入分配给变量，因此我认为您的输出只是一堆 0 值？
您可能正在寻找更像这样的东西：
for (int i = 0; i < userArray.length; i++)
for(int j = 0; j < userArray[i].length; j++)
{
System.out.println("Please enter numbers between -10 and 10 for your matrix");
int valueIn = input.nextInt();
while (valueIn > 10 || valueIn < -10)
{
System.out.println("Sorry. Your number is not the correct size. " + "Please enter a number between 10 and -10.");
valueIn = input.nextInt();
}
userArray[i][j]=valueIn;
}
您需要一个嵌套循环，以读取行级的值，然后读取列级的值。如下所示：
import java.util.Scanner;
public class Matrix {
public static void main(String[] args) {
// TODO Auto-generated method stub
// Implement scanner
Scanner input = new Scanner(System.in);
// create loop for accepting matrix input
// first accept row size
System.out.println("Please enter the number of rows in your matrix. Must be 5 or less.");
int row = input.nextInt();
while (row > 5 || row < 1) {
System.out.println("Sorry. Your number is not the correct size. "
+ "Please enter the number of rows in your matrix. Must be between 5 and 1.");
row = input.nextInt();
}
// next accept column size
System.out.println("Please enter the number of columns in your matrix. Must be 5 or less.");
int column = input.nextInt();
while (column > 5 || column < 1) {
System.out.println("Sorry. Your number is not the correct size. "
+ "Please enter the number of columns in your matrix. Must be between 5 and 1.");
column = input.nextInt();
}
// declare array with row and columns the user gave
int[][] userArray = new int[row][column];
for(int i=0;i< row ; i++){
for(int j=0; j< column; j++) {
System.out.print("Please enter the value for array["+i+"]["+j+"] (between -10 and 10):");
int val = input.nextInt();
if(val>10 || val< -10) {
System.out.println("Invalid value.");
continue;
}
userArray[i][j] = val;
}
}
printMatrix(userArray, row, column);
}
public static void printMatrix(int[][] array, int row, int column) {
for (int i = 0; i < row; i++) {
for (int j = 0; j < column; j++) {
System.out.print(array[i][j] + " ");
}
System.out.println();
}
}
}
public class Matrix {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Enter number of rows.");
int rows = getValueFromConsole(scan, 1, 5);
System.out.println("Enter number of columns.");
int cols = getValueFromConsole(scan, 1, 5);
System.out.println("Enter matrix data.");
int[][] matrix = createMatrix(scan, rows, cols, -99, 99);
printMatrix(matrix);
}
private static int[][] createMatrix(Scanner scan, int rows, int cols, int min, int max) {
int[][] matrix = new int[rows][cols];
for (int row = 0; row < rows; row++)
for (int col = 0; col < cols; col++)
matrix[row][col] = getValueFromConsole(scan, min, max);
return matrix;
}
private static int getValueFromConsole(Scanner scan, int min, int max) {
while (true) {
System.out.format("Number [%d:%d]: ", min, max);
int val = scan.nextInt();
if (val >= min && val <= max)
return val;
System.out.println("Sorry. Your number is not correct. Try again.");
}
}
private static void printMatrix(int[][] matrix) {
for (int row = 0; row < matrix.length; row++) {
for (int col = 0; col < matrix[row].length; col++)
System.out.format("%4d", matrix[row][col]);
System.out.println();
}
}
}
输出：
Enter number of rows.
Number [1:5]: 3
Enter number of columns.
Number [1:5]: 3
Enter matrix data.
Number [-99:99]: 10
Number [-99:99]: -11
Number [-99:99]: 12
Number [-99:99]: -13
Number [-99:99]: 14
Number [-99:99]: -15
Number [-99:99]: 16
Number [-99:99]: -17
Number [-99:99]: 18
10 -11 12
-13 14 -15
16 -17 18