CODEWITHSUNDEEP
javaarrays
user2484149
user2484149

Reputation: 31

printing a two dimensional matrix (array) java

I need to print this in the correct two dimensional array format. SOmething is wrong. Need the print from the method. My output is what seems to be an infinite loop.

import java.util.Scanner;
public class hw3 {
public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    System.out.println("What is the dimension of your matrix?");
    int matrixdim = input.nextInt();
    double[][] matrix = new double[matrixdim][matrixdim];

    System.out.println("Enter " + matrixdim + " rows, and " + matrixdim + " columns." );
    Scanner input1= new Scanner(System.in);
    for (int row = 0; row < matrix.length; row++) {
        for (int column = 0; column < matrix[row].length; column++)
            matrix[row][column] = input1.nextDouble();
    }
    System.out.println("Your original array:");

    System.out.println(printArray(matrix));
}   
public static double printArray(double matrix[][]){
    for (int row = 0; row < matrix.length; row++) {
        for (int column = 0; column < matrix[row].length;column++) {
        System.out.println(matrix[row][column] + " ");
    }
    System.out.println();
}
return printArray(matrix);

Upvotes: 1

Views: 43364

Answers (4)

Pshemo
Pshemo

Reputation: 124215

As I told you in my previous answer invoking same method again return printArray(matrix); at the end of your method can lead to invoking it again (and again) until StackOverflow error.

Change return type to void. Now your method can look like 

public static void printArray(double matrix[][]) {
    for (int row = 0; row < matrix.length; row++) {
        for (int column = 0; column < matrix[row].length; column++) {
            System.out.print(matrix[row][column] + " ");
        }
        System.out.println();
    }
}

or even better

public static void printArray(double matrix[][]) {
    for (double[] row : matrix) 
        System.out.println(Arrays.toString(row));       
}

Upvotes: 12

darijan
darijan

Reputation: 9775

Just change the println to print in the first print call. 

public static void printArray(double matrix[][]){
    for (...) {
        for (...) {
            //here just print goes
            System.out.print(matrix[row][column] + " ");
        }
        //at the end each row of the matrix you want the new line - println is good here
        System.out.println();
    }
}

print does not print the newline (\n) at the end of the output, whereas the println does. That's why you're getting the ugly print.

Also, printArray should not return a value, it should be:

public static void printArray(double[][] matrix)

I think that's where you're getting your infinite loop. Don't return anything - no need, you are just printing it.

Upvotes: 2

Artur Dębski
Artur Dębski

Reputation: 34

you got System.out.println(printArray(matrix)); instead of printArray(matrix); since your method got print calls in it anyway

and as mentioned above - print vs println

Upvotes: -1

Simon Arsenault
Simon Arsenault

Reputation: 1845

You are missing a } and use print instead of println inside your 2nd loop.

public static double printArray(double matrix[][])
{
    for (int row = 0; row < matrix.length; row++) 
    {
        for (int column = 0; column < matrix[row].length;column++) 
        {
            System.out.print(matrix[row][column] + " ");
        }
        System.out.println();
    }
}

Upvotes: 1

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