How to convert double[] to Double[] in Java?

Approach 1: Traversing to each element and convert.

public static Double[] getBoxedArray_approach1(double[] arr) {
 if (arr == null)
  return null;

 Double[] result = new Double[arr.length];
 int index = 0;
 for (double i : arr) {
  result[index] = Double.valueOf(i);
  index++;
 }
 return result;
}

Approach 2: Using ‘Arrays.stream’.

Double[] result = Arrays.stream(arr).boxed().toArray(Double[]::new);

Approach 3: Using DoubleStream.

Double[] result = DoubleStream.of(arr).boxed().toArray(Double[]::new);

App.java

package com.sample.app;

import java.util.Arrays;
import java.util.stream.DoubleStream;

public class App {

 private static void printElements(Double[] arr) {
  for (double i : arr) {
   System.out.print(i + " ");
  }
  System.out.println();
 }

 public static Double[] getBoxedArray_approach1(double[] arr) {
  if (arr == null)
   return null;

  Double[] result = new Double[arr.length];
  int index = 0;
  for (double i : arr) {
   result[index] = Double.valueOf(i);
   index++;
  }
  return result;
 }
 
 public static Double[] getBoxedArray_approach2(double[] arr) {
  if (arr == null)
   return null;

  Double[] result = Arrays.stream(arr).boxed().toArray(Double[]::new);
  return result;
 }
 
 public static Double[] getBoxedArray_approach3(double[] arr) {
  if (arr == null)
   return null;

  Double[] result = DoubleStream.of(arr).boxed().toArray(Double[]::new);
  return result;
 }

 public static void main(String args[]) {
  double[] arr = { 1.1, 3.3, 5.5, 7.7, 2.2, 4.4, 6.6, 8.8, 10.10 };

  Double[] result1 = getBoxedArray_approach1(arr);
  Double[] result2 = getBoxedArray_approach2(arr);
  Double[] result3 = getBoxedArray_approach3(arr);

  printElements(result1);
  printElements(result2);
  printElements(result3);

 }

}

Output

1.1 3.3 5.5 7.7 2.2 4.4 6.6 8.8 10.1

1.1 3.3 5.5 7.7 2.2 4.4 6.6 8.8 10.1

1.1 3.3 5.5 7.7 2.2 4.4 6.6 8.8 10.1

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