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stackoverflow.com › questions › 1109988 › how-do-i-convert-double-to-double

If you don't mind using a 3rd party library, commons-lang has the ArrayUtils type with various methods for manipulation.

Double[] doubles;
...
double[] d = ArrayUtils.toPrimitive(doubles);

There is also the complementary method

doubles = ArrayUtils.toObject(d);

Edit: To answer the rest of the question. There will be some overhead to doing this, but unless the array is really big you shouldn't worry about it. Test it first to see if it is a problem before refactoring.

Implementing the method you had actually asked about would give something like this.

double[] getDoubles(int columnIndex) {
    return ArrayUtils.toPrimitive(data[columnIndex]);
}

Answer from Rich Seller on Stack Overflow

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stackoverflow.com › questions › 1109988 › how-do-i-convert-double-to-double

java - How do I convert Double[] to double[]? - Stack Overflow

Top answer

1 of 8

96

If you don't mind using a 3rd party library, commons-lang has the ArrayUtils type with various methods for manipulation.

Double[] doubles;
...
double[] d = ArrayUtils.toPrimitive(doubles);

There is also the complementary method

doubles = ArrayUtils.toObject(d);

Edit: To answer the rest of the question. There will be some overhead to doing this, but unless the array is really big you shouldn't worry about it. Test it first to see if it is a problem before refactoring.

Implementing the method you had actually asked about would give something like this.

double[] getDoubles(int columnIndex) {
    return ArrayUtils.toPrimitive(data[columnIndex]);
}

2 of 8

61

In Java 8, this is one-liner:

Double[] boxed = new Double[] { 1.0, 2.0, 3.0 };
double[] unboxed = Stream.of(boxed).mapToDouble(Double::doubleValue).toArray();

Note that this still iterates over the original array and creates a new one.

TutorialsPoint

tutorialspoint.com › convert-double-primitive-type-to-a-double-object-in-java

Convert double primitive type to a Double object in Java

JavaObject Oriented ProgrammingProgramming · To convert double primitive type to a Double object, you need to use Double constructor. Let’s say the following is our double primitive. // double primitive double val = 23.78; To convert it to a Double object, use Double constructor.

Discussions

cannot convert from double to double[]?

Need to tell it where to put it in the array. Something like amounts[0] = sc.nextDouble(); Or for (int i = 0; i < amounts.length; ++i) { amounts[i] = sc.nextDouble(); } More on reddit.com

r/javahelp

4

8

February 20, 2019

Convert java double to Double object Example July 14, 2019 4 Comments 1 Min Read 1 2 3 Convert double to Double object Example This example shows how a double primitive value can be converted to a Double object */ 4 5 6 public class JavadoubleToDoubleExample { 7 8 public static void main(String[] args) { double d = 10.56; 9 10 11 12 Use Double constructor to

Convert java double to Double object Example July 14, 2019 4 Comments 1 Min Read 1 2 3 Convert double to Double object Example This example shows how a double primitive value can be converted to a Double object */ 4 5 6 public class JavadoubleToDoubleExample { 7 8 public static void main(String[] ... More on chegg.com

chegg.com

1

May 24, 2021

Double[] instead of double[] variable declarator

Hi everyone i have a problem with java snippet. when i need as output an array of double the snippet automaticaly set Double which doesn’t exist as type. Possible bug? More on forum.knime.com

forum.knime.com

0

March 6, 2018

[Java] Possible lossy conversion from double to int error.

If you want to explicitly tell the compiler that you want to convert the numbers to integers, you should cast them as such. Example: int x = (int)(10.0/2.0) will make x have a value of 5.

Do note, however, that in the case of int birthrate, the operation 1.0/7.0 will simply be 0 when cast to an int.

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