Necessary create a 2D matrix (array) sizes m*b:
- Filled in by manually, found Null, print results
- Filled in by automatically:
- create a File -> record File.txt
- read in created File.txt
- found Null
- print results
package labs1;
import java.io.*;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.*;
public class labs2 {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Add size matrix m*n nnumber of row m =");
int m = Integer.parseInt(reader.readLine());
System.out.println("number of columns n =");
int n = Integer.parseInt(reader.readLine());
int[][] matrix = new int[m][n];
System.out.println("Choose to method assignments matrix n0-manually n1-automatically");
int k = Integer.parseInt(reader.readLine());
while (true) {
if (k == 0) {
//
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
matrix[i][j] = Integer.parseInt(reader.readLine());
}
}
// print matrix
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println("");
}
//count of null in matrix
int count = 0;
for (int i = 0; i < matrix.length; i++) {
for (int j = 0; j < matrix[i].length; j++)
if (matrix[i][j] == 0) {
count++;
}
}
System.out.println("Quantity of Null in matrix: " + count);
}
//Assignment matrix automatically - Random
if (k == 1) {
for (int i = 0; i < matrix.length; i++) {
// do the for in the row according to the column size
for (int j = 0; j < matrix[i].length; j++) {
// multiple the random by 10 and then cast to in
matrix[i][j] = ((int) (Math.random() * 10));
}
}
// print matrix
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println("");
}
//count of null in matrix
int count = 0;
for (int i = 0; i < matrix.length; i++) {
for (int j = 0; j < matrix[i].length; j++)
if (matrix[i][j] == 0) {
count++;
}
}
System.out.println("Quantity of Null in matrix: " + count);
//Create a File .txt
// String Builder to create the table structure before writing it to the file.
StringBuilder sb = new StringBuilder();
for (int[] int1 : matrix) {
for (int j = 0; j < int1.length; j++) {
sb.append(int1[j]).append("t"); // Add tab to delimite the elements
}
sb.append("n"); // Add new line character
}
System.out.println("nMatrix record in filen" + sb);
// The path to your file
Path path = Paths.get("D:\labs1.txt");
// Writes to that path the bytes in the string from the stringBuilder object.
Files.write(path, sb.toString().getBytes());
ArrayList<int[]> list = readMaze("D:\labs1.txt");
System.out.println(Arrays.toString(list.toArray()));
}
if (k != 0 | k != 1) {
break;
}
}
}
//Reading in File
public static ArrayList<int[]> readMaze(String fileName) {
// Number of ints per line:
int width = 2;
// This will be the output - a list of rows, each with 'width' entries:
ArrayList<int[]> results = new ArrayList<int[]>();
String line = null;
try {
FileReader fileReader = new FileReader(fileName);
BufferedReader bufferedReader = new BufferedReader(fileReader);
Scanner mazeRunner = new Scanner(bufferedReader);
// While we've got another line..
while (mazeRunner.hasNextLine()) {
// Setup current row:
int[] row = new int[width];
// For each number..
for (int i = 0; i < width; i++) {
// Read the number and add it to the current row:
row[i] = mazeRunner.nextInt();
}
// Add the row to the results:
results.add(row);
// Go to the next line (optional, but helps deal with erroneous input files):
if (mazeRunner.hasNextLine()) {
// Go to the next line:
mazeRunner.nextLine();
}
}
mazeRunner.close();
} catch (FileNotFoundException ex) {
System.out.println("Unable to open file: " + fileName);
} catch (IOException ex) {
System.out.println("Error reading file: " + fileName);
}
return results;
}
}
I used public static readMaze from here – https://stackoverflow.com/questions/41632526/reading-a-text-file-into-a-2d-array
Print to the console:
Add size matrix m*n number of row m = 4 number of columns n = 2 Choose to method assignments matrix 0-manually 1-automatically 1 1 0 9 3 6 3 0 2 Quantity of Null in matrix: 2 Matrix record in file 1 0 9 3 6 3 0 2 [[I@5e9f23b4, [I@4783da3f, [I@378fd1ac, [I@49097b5d] Process finished with exit code 0
But this code incorrect reading and printing 2D matrix(array)
[[I@5e9f23b4, [I@4783da3f, [I@378fd1ac, [I@49097b5d]
I doubt about this code:
ArrayList<int[]> list = readMaze("D:\labs1.txt"); System.out.println(Arrays.toString(list.toArray()));
Please Help me, this’s need me to finish task in the University
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Answer
You are getting this result because you are printing the elements of ArrayList instead of the int[] arrays contained within that ArrayList. It should be something like this:
Replace this code (only):
ArrayList<int[]> list = readMaze("D:\labs1.txt");
System.out.println(Arrays.toString(list.toArray()));
With this code:
ArrayList<int[]> list = readMaze("D:\labs1.txt");
for (int[] intArray : list) {
System.out.println(Arrays.toString(intArray));
}