Extracting a Row/Column from An Array

[besweeet]

I need to extract a row given [il]n[/il], print it out horizontally on the screen, and return it as a 1D-Array.

Here's my code so far:

	public static int[] extractRow(int [][] array1, int n){
		for (int row = 0; row<=array1.length; row++){
				System.out.println(array1[n] + "\t");}
		return array1[n];}

In main, I made an input scanner where the user will enter an integer from 1-10, called n, which is being passed to that method.

The output is usually something like [I@68916a2.

Any ideas? Once I get this finished, I can do the same thing for a column, and I'll be done :).

[Fubarable]

What you're seeing is the default toString() result from an array. To print out a one-dimensional array, either loop through it, printing each item as you loop, use the Arrays utility class's static method toString:

System.out.println(java.util.Arrays.toString(myArray));

[besweeet]

What you're seeing is the default toString() result from an array. To print out a one-dimensional array, either loop through it, printing each item as you loop, use the Arrays utility class's static method toString:

System.out.println(java.util.Arrays.toString(myArray));

I don't understand how to do either one of those. I've never used the second. The first one sounds easier, but I don't know what to write out.

[Webuser]

well, first of all you want to extract int [][] array :)

you should use two loops to scan [][] array ;)

Modify your code as I did :D

public static int[] extractRow(int [][] array1, int n){
		for (int row = 0; row<=array1.length; row++){
		for(int j=0; j<array1[row].length;j++)
                              {
                              System.out.println(array1[row][j] + "\t");
                              }		
                             
                       }
		return array1[n];
                     }

[Webuser]

The output is usually something like [I@68916a2.

That is all because you put out an array instead of its element

[besweeet]

Someone suggested me to use this:

        public static int[] extractRow(int [][] array1, int n){
                for (int row = 0; row<array1.length; row++){
                        if (n == array1[n])

It worked, but I don't understand what the for loop is doing here... I'm not good at tracing loops either.

[Webuser]

Someone suggested me to use this:

        public static int[] extractRow(int [][] array1, int n){
                for (int row = 0; row<array1.length; row++){
                        if (n == array1[n])

It worked, but I don't understand what the for loop is doing here... I'm not good at tracing loops either.

To scan and show each array element ;)

[besweeet]

To scan and show each array element ;)

What do you mean by "each array element"? Sorry for being such a noob... It's just that I am one :cool:.

[Webuser]

if (n == array1[n])

It means that array1[n] is supposed to contain the array indexes :) But it is no good to use the code style :(

[Webuser]

you should better use the loop iterator instead ;)

if(n==i)...

[JosAH]

well, first of all you want to extract int [][] array :)

you should use two loops to scan [][] array ;)

Modify your code as I did :D

public static int[] extractRow(int [][] array1, int n){
		for (int row = 0; row<=array1.length; row++){
		for(int j=0; j<array1[row].length;j++)
                              {
                              System.out.println(array1[row][j] + "\t");
                              }		
                             
                       }
		return array1[n];
                     }

This is utter nonsense; extracting row i (0 <= i < n) from a two dimensional array a[n][m] is simply a[i]. You need just one loop to print out all the elements of the row or use a static Arrays.toString(a[i]) call; btw, please don't beg for rep points.

kind regards,

Jos