How to print two 2D double arrays?

Question

Like from {{1.0,2.0},{3.0,4.0}} and {{0.1,0.2},{0.3,0.4}} to {{1.1,2.2},{3.3,4.4}}. If the two input arrays are different sizes, method should return null.

My code below shows [[D@6d06d69c.

What is wrong with my code?

public class Homework13_1 {

    public static double[][] sum(double[][]a,double[][]b){
        double[][] newA= new double[a.length][a[0].length];
        int c=0;
        if ((a.length==b.length)){
            for (int i=0;i<a.length;i++){
                for(int j=0;j<a[0].length;j++){
                    newA[i][j]=a[i][j]+b[i][j];

                }

            }

            return newA;


        }
        else{
            return null;


        }

    }

    public static void main(String[] args) {
        double[][]x={{1,2,3},{2,3,4}};
        double[][]y={{2,3,4},{1,1,1}};
        double[][] b = {{1,2,-9,7},{3,4,9.9,1.2}};


        System.out.println(sum(x, y));


    }

}

your `sum()` function is returning a 2d array. seems like it should be returning an int right? — Andy Guibert, Nov 06 '15 at 02:43
flagging to close this as off-topic since it's a "do my homework for me" question. — Andy Guibert, Nov 06 '15 at 02:45
Possible duplicate of [What's the simplest way to print a Java array?](http://stackoverflow.com/questions/409784/whats-the-simplest-way-to-print-a-java-array) — Erwin Bolwidt, Nov 06 '15 at 06:13

score 0 · Answer 1 · answered Nov 06 '15 at 02:44

Java arrays don't override toString. But there is Arrays.deepToString(Object[]) which says (in part) This method is designed for converting multidimensional arrays to strings. You could change

System.out.println(sum(x, y));

to

System.out.println(Arrays.deepToString(sum(x, y)));

How to print two 2D double arrays?

1 Answers1