CODEWITHSUNDEEP
javaarraysmultidimensional-array
Abhishek Kumar
Abhishek Kumar

Reputation: 900

Copy 1D array to a row of a 2D array

int n = 5;
int[] oneD = new int[5];
int[] oneD2 = new int[5];
int[] oneD3 = new int[5];
.
.
.
n

int[][] twoD = new int[n][5];

How can the three oned arrays in java can be copied to seperate rows of the 2D array? Actually, is there some short and lovely handy feature in java 8+ to do so?

Upvotes: 0

Views: 446

Answers (2)

WJS
WJS

Reputation: 40057

Here is your Java 8 solution. It simply creates new arrays and combines them into a 2D array. The 2D arrays are independent of the originals. Thanks to Andreas for the int[]::clone tip.

int n = 5;
int[] oned = new int[5];
int[] oned2 = new int[5];
int[] oned3 = new int[5];
.
.
.
n

int[][] twod = Stream.of(oned, oned2, oned3,...,onedn)
        .map(int[]::clone)
        .toArray(int[][]::new);

Upvotes: 0

Andreas
Andreas

Reputation: 159250

Two options:

  1. Don't "copy" the arrays, use them:

    int[][] twod = new int[][] { oned, oned2, oned3 };

    OR:

    twod[0] = oned;
twod[1] = oned2;
twod[2] = oned3;

    E.g. twod[1][3] and oned2[3] now refer to the same value, so changing one changes the other.

  2. Copy the array contents:

    System.arraycopy(oned, 0, twod[0], 0, 5);
System.arraycopy(oned2, 0, twod[1], 0, 5);
System.arraycopy(oned3, 0, twod[2], 0, 5);

    twod is now entirely independent of the other arrays.

Upvotes: 5

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