Java 是否可以从一个文件创建两个不同大小的数组/矩阵?
基本上,我尝试从一个文本文件创建两个不同大小的2D数组,如下所示:Java 是否可以从一个文件创建两个不同大小的数组/矩阵?,java,matrix,multidimensional-array,Java,Matrix,Multidimensional Array,基本上,我尝试从一个文本文件创建两个不同大小的2D数组,如下所示: 2 add 3 4 2 1 7 -10 0 5 -3 12 1 7 -2 -5 0 1 2 3 4 5 6 7 8 9 0 1 subtract 2 2 2 12 10 0 4 6 9 1 2是问题数(加法和减法),3和4是行数和列数,下面的数字是填充到2D数组中的两个独立矩阵。如果我就到此为止,该程序将正常工作: class Matrices { private Scanner fileReader; private in
2
add
3 4
2 1 7 -10
0 5 -3 12
1 7 -2 -5
0 1 2 3
4 5 6 7
8 9 0 1
subtract
2 2
2 12
10 0
4 6
9 1
2
是问题数(加法和减法),3
和4
是行数和列数,下面的数字是填充到2D数组中的两个独立矩阵。如果我就到此为止,该程序将正常工作:
class Matrices {
private Scanner fileReader;
private int rows;
private int columns;
int problems;
String method;
public Matrices(String file) throws FileNotFoundException {
this.fileReader = new Scanner(new FileInputStream(file));
problems = fileReader.nextInt();
method = fileReader.next();
if(method.equals("add")) {
rows = fileReader.nextInt();
columns = fileReader.nextInt();
}
}
public int[][] readMatrix() throws FileNotFoundException {
int[][] result = new int[rows][columns];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
result[i][j] = fileReader.nextInt();
}
}
return result;
}
public int[][] add(int[][] a, int[][] b) {
int[][] result = new int[rows][columns];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
result[i][j] = a[i][j] + b[i][j];
}
}
return result;
}
public void printMatrix(int[][] matrix) {
for ( int[] anArray : matrix ) {
for ( int anInt : anArray ) {
System.out.print(anInt+ " ");
}
System.out.println();
}
}
}
它创建和打印矩阵非常好,没有任何问题。但是,每当我尝试创建和打印下两个矩阵(文本文件中下面的2x2数组减法)时,它都会返回以下错误:
Enter name of file:
data/Matrices.txt
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:862)
at java.util.Scanner.next(Scanner.java:1485)
at java.util.Scanner.nextInt(Scanner.java:2117)
at java.util.Scanner.nextInt(Scanner.java:2076)
at baker.Matrices.readMatrix(Matrices.java:27)
at baker.MatricesDriver.main(MatricesDriver.java:15
我的问题是,我应该做哪些调整,以便程序识别出两个2D阵列为3x4,以下两个为2x2?您试图构建数据结构 您可以使用:
对于创建没有固定大小的数组或向量使用arrayList,您可以从arrayList创建arrayList我建议将实现分解为以下部分:
- 类
-保存问题定义中一个矩阵的值矩阵
- 类
-保存问题定义中的操作和两个矩阵问题
矩阵
类可以如下所示:
class Matrix {
private int[][] values;
public Matrix(int[][] values) {
this.values = values;
}
public int[][] getValues() {
return values;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("Matrix [values=\n");
for (int i = 0; i < values.length; i++) {
sb.append("\t" + Arrays.toString(values[i]) + "\n");
}
sb.append("]");
return sb.toString();
}
}
基于此,“驱动程序”类执行以下操作:
import java.io.FileInputStream;
导入java.io.FileNotFoundException;
导入java.util.ArrayList;
导入java.util.array;
导入java.util.List;
导入java.util.Scanner;
公共类矩阵驱动程序{
公共静态void main(字符串[]args)引发FileNotFoundException{
扫描仪键盘=新扫描仪(System.in);
System.out.println(“输入文件名:”);
字符串文件名=keyboard.next();
列出问题=读取问题(文件名);
系统输出打印(问题);
键盘关闭();
}
私有静态列表读取问题(最终字符串文件名)引发FileNotFoundException{
Scanner fileReader=new Scanner(new FileInputStream(filename));
int numberOfProblems=fileReader.nextInt();
列表问题=新数组列表(numberOfProblems);
对于(int i=1;i是给定的文本格式?文本文件?是的,它与这里列出的一样,没有空格,也没有单独的文件。没有空格,我的意思是行与行之间没有空格,对歧义表示歉意。主要问题是,在MatricesDriver的构造函数中,只初始化一次行和列。这意味着它正在导出3和4。以及lat呃,如果你第三次调用readMatrix,它仍然在处理这些维度。你需要将文件读取与矩阵/问题读取分开。这只是一个定义所有矩阵的巨大方法吗?还是一堆get方法?抱歉,我对这一点很陌生。代码的最终游戏是两个添加3x4矩阵和子矩阵计算2x2矩阵,然后打印出来。我认为我的思路正确,我更新了代码。好的。请您将答案标记为有用或正确,以结束本主题。谢谢。哦,是的,对不起。给您。再次感谢
class Matrix {
private int[][] values;
public Matrix(int[][] values) {
this.values = values;
}
public int[][] getValues() {
return values;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("Matrix [values=\n");
for (int i = 0; i < values.length; i++) {
sb.append("\t" + Arrays.toString(values[i]) + "\n");
}
sb.append("]");
return sb.toString();
}
}
class Problem {
private String operation;
private Matrix first;
private Matrix second;
public Problem(String operation, Matrix firstMatrix, Matrix secondMatrix) {
this.operation = operation;
first = firstMatrix;
second = secondMatrix;
}
public String getOperation() {
return operation;
}
public Matrix getFirst() {
return first;
}
public Matrix getSecond() {
return second;
}
@Override
public String toString() {
return "Problem [\noperation=" + operation + ", \nfirst=" + first + ", \nsecond=" + second + "\n]";
}
}
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
public class MatricesDriver {
public static void main(String[] args) throws FileNotFoundException {
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter name of file: ");
String filename = keyboard.next();
List<Problem> problems = readProblems(filename);
System.out.println(problems);
keyboard.close();
}
private static List<Problem> readProblems(final String filename) throws FileNotFoundException {
Scanner fileReader = new Scanner(new FileInputStream(filename));
int numberOfProblems = fileReader.nextInt();
List<Problem> problems = new ArrayList<>(numberOfProblems);
for (int i = 1; i <= numberOfProblems; i++) {
problems.add(readProblem(fileReader));
}
fileReader.close();
return problems;
}
private static Problem readProblem(Scanner fileReader) throws FileNotFoundException {
fileReader.nextLine(); // go to next line
String operation = fileReader.nextLine(); // read problem operation
int rows = fileReader.nextInt(); // read number of rows
int columns = fileReader.nextInt(); // read number of columns
Matrix firstMatrix = readMatrix(rows, columns, fileReader);
Matrix secondMatrix = readMatrix(rows, columns, fileReader);
return new Problem(operation, firstMatrix, secondMatrix);
}
private static Matrix readMatrix(final int rows, final int columns, final Scanner fileReader) throws FileNotFoundException {
int[][] result = new int[rows][columns];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
result[i][j] = fileReader.nextInt();
}
}
return new Matrix(result);
}
}