I was wondering what the best way of printing a 2D array in Java was?
I was just wondering if this code is good practice or not?
Also any other mistakes I made in this code if you find any.
int rows = 5;
int columns = 3;
int[][] array = new int[rows][columns];
for (int i = 0; i<rows; i++)
for (int j = 0; j<columns; j++)
array[i][j] = 0;
for (int i = 0; i<rows; i++) {
for (int j = 0; j<columns; j++) {
System.out.print(array[i][j]);
}
System.out.println();
}
You can print in simple way.
Use below to print 2D array
int[][] array = new int[rows][columns];
System.out.println(Arrays.deepToString(array));
Use below to print 1D array
int[] array = new int[size];
System.out.println(Arrays.toString(array));
System.out.println(Arrays.deepToString(twoDm).replace("], ", "]\n"));I would prefer generally foreach when I don't need making arithmetic operations with their indices.
for (int[] x : array)
{
for (int y : x)
{
System.out.print(y + " ");
}
System.out.println();
}
List<Integer> instead of int[]. It looks similar but one needs to use the type of an ArrayList of Integers to this for (List<Integer> a : arr) for the first line of code.Simple and clean way to print a 2D array.
System.out.println(Arrays.deepToString(array).replace("], ", "]\n").replace("[[", "[").replace("]]", "]"));
There is nothing wrong with what you have. Double-nested for loops should be easily digested by anyone reading your code.
That said, the following formulation is denser and more idiomatic java. I'd suggest poking around some of the static utility classes like Arrays and Collections sooner than later. Tons of boilerplate can be shaved off by their efficient use.
for (int[] row : array)
{
Arrays.fill(row, 0);
System.out.println(Arrays.toString(row));
}
Two-liner with new line:
for(int[] x: matrix)
System.out.println(Arrays.toString(x));
One liner without new line:
System.out.println(Arrays.deepToString(matrix));
That's the best I guess:
for (int[] row : matrix){
System.out.println(Arrays.toString(row));
}
|1 2 3|
|4 5 6|
Use the code below to print the values.
System.out.println(Arrays.deepToString());
Output will look like this (the whole matrix in one line):
[[1,2,3],[4,5,6]]
From Oracle Offical Java 8 Doc:
public static String deepToString(Object[] a)
Returns a string representation of the "deep contents" of the specified array. If the array contains other arrays as elements, the string representation contains their contents and so on. This method is designed for converting multidimensional arrays to strings.
With Java 8 using Streams and ForEach:
Arrays.stream(array).forEach((i) -> {
Arrays.stream(i).forEach((j) -> System.out.print(j + " "));
System.out.println();
});
The first forEach acts as outer loop while the next as inner loop
System.out.println(Arrays.deepToString(array)
.replace("],","\n").replace(",","\t| ")
.replaceAll("[\\[\\]]", " "));
You can remove unwanted brackets with .replace(), after .deepToString if you like.
That will look like:
1 | 2 | 3
4 | 5 | 6
7 | 8 | 9
10 | 11 | 12
13 | 15 | 15
@Ashika's answer works fantastically if you want (0,0) to be represented in the top, left corner, per standard matrix convention. If however you would prefer to put (0,0) in the lower left hand corner, in the style of the standard coordinate system, you could use this:
LinkedList<String> printList = new LinkedList<String>();
for (char[] row: array) {
printList.addFirst(Arrays.toString(row));;
}
while (!printList.isEmpty())
System.out.println(printList.removeFirst());
This used LIFO (Last In First Out) to reverse the order at print time.
Try this,
for (char[] temp : box) {
System.err.println(Arrays.toString(temp).replaceAll(",", " ").replaceAll("\\[|\\]", ""));
}
Adapting from https://stackoverflow.com/a/49428678/1527469 (to add indexes):
System.out.print(" ");
for (int row = 0; row < array[0].length; row++) {
System.out.print("\t" + row );
}
System.out.println();
for (int row = 0; row < array.length; row++) {
for (int col = 0; col < array[row].length; col++) {
if (col < 1) {
System.out.print(row);
System.out.print("\t" + array[row][col]);
} else {
System.out.print("\t" + array[row][col]);
}
}
System.out.println();
}
class MultidimensionalArray {
public static void main(String[] args) {
// create a 2d array
int[][] a = {
{1, -2, 3},
{-4, -5, 6, 9},
{7},
};
// first for...each loop access the individual array
// inside the 2d array
for (int[] innerArray: a) {
// second for...each loop access each element inside the row
for(int data: innerArray) {
System.out.println(data);
}
}
}
}
You can do it like this for 2D array
