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javaarrays
shamy
shamy

Reputation: 35

convert multi array into single array(java)

is it possible to copy the data from multi[][] to single[]?!?

double multi[][] = { {1.0, 2.0}, {2.11, 204.00, 11.00, 34.00},{66.5,43.3,189.6}};

to 

double single [] = {1.0, 2.0, 2.11, 204.00, 11.0, 66.5,43.3,189.6}

Upvotes: 0

Views: 3005

Answers (4)

assylias
assylias

Reputation: 328913

With Java 8 you can write:

double[] single = Arrays.stream(multi) //Creates a Stream<double[]>
            .flatMapToDouble(Arrays::stream) //merges the arrays into a DoubleStream
            .toArray(); //collects everything into a double[] array

Upvotes: 4

Ted Hopp
Ted Hopp

Reputation: 234857

It's entirely possible. Per @assylias's answer, Java 8 has a very nice solution. If you're not using Java 8, you'll have to do some work by hand. Since the multi elements are different length, The most efficient thing to do would be to use two passes: the first to count how many elements you need in the result and the second to actually copy the elements once you've allocated the array:

int n = 0;
for (int[] elt : multi) {
    n += elt.length;
}
double[] single = new double[n];
n = 0;
for (int[] elt : multi) {
    System.arraycopy(elt, 0, single, n, elt.length);
    n += elt.length;
}

If it is at all possible that an element of multi is null, you'd want to add an appropriate check inside each of the loops.

Upvotes: 2

Madhawa Priyashantha
Madhawa Priyashantha

Reputation: 9900

if you want a logical way..first you have to find the length of multy array content .and then make single [] with that length and add values 

double multy[][] = { {1.0, 2.0}, {2.11, 204.00, 11.00, 34.00},{66.5,43.3,189.6}};
int y=0;
for(int x=0;x<multy.length,x++){
    for(int i=0;i<multy[x].length,i++){
       y++;
    }
}
double single [] =new double[y];
y=0;

for(int x=0;x<multy.length,x++){
    for(int i=0;i<multy[x].length,i++){
       y++;
       single[y]==multy[x][i];
    }
}

Upvotes: 1

sukotto1
sukotto1

Reputation: 190

According to: https://stackoverflow.com/questions/20686499/java-how-to-convert-a-multidimensional-array-to-single-array-easily

ArrayUtils.addAll(array1,array2)

Upvotes: 0

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