Flatten nested arrays in java

by

The Stream API offers a compact and flexible solution. Using the method

private static Stream<Object> flatten(Object[] array) {
    return Arrays.stream(array)
        .flatMap(o -> o instanceof Object[] a? flatten(a): Stream.of(o));
}

or prior to JDK 16

private static Stream<Object> flatten(Object[] array) {
    return Arrays.stream(array)
        .flatMap(o -> o instanceof Object[]? flatten((Object[])o): Stream.of(o));
}

you can perform the operation as

Object[] array = { 1, 2, new Object[]{ 3, 4, new Object[]{ 5 }, 6, 7 }, 8, 9, 10 };
System.out.println("original: "+Arrays.deepToString(array));

Object[] flat = flatten(array).toArray();
System.out.println("flat:     "+Arrays.toString(flat));

or when you assume the leaf objects to be of a specific type:

int[] flatInt = flatten(array).mapToInt(Integer.class::cast).toArray();
System.out.println("flat int: "+Arrays.toString(flatInt));

More Related Contents:

  1. How to remove repetition in output results in this code
  2. Write a program that takes an array/arraylist of integer and finds longest sub array/arraylist whose entries are equal [closed]
  3. Finding the max/min value in an array of primitives using Java
  4. Connect 4 check for a win algorithm
  5. Quickest way to find missing number in an array of numbers
  6. Finding the second highest number in array
  7. Java, find intersection of two arrays
  8. Java, Shifting Elements in an Array
  9. Find duplicate element in array in time O(n)
  10. All possible combinations of an array
  11. How to find the only number in an array that doesn’t occur twice [duplicate]
  12. Generate Random Numbers in Array [duplicate]
  13. find an element in a sorted matrix [duplicate]
  14. Interview question – Search in sorted array X for index i such that X[i] = i
  15. In selection sort, if we have two duplicate elements, what is the behavior of the algorithm?
  16. Java while loop query [closed]
  17. How do I declare and initialize an array in Java?
  18. Are arrays passed by value or passed by reference in Java? [duplicate]
  19. Where is array’s length property defined?
  20. Java: Reading a file into an array
  21. How to map a PostgreSQL array with Hibernate
  22. Can an array be used as a HashMap key?
  23. varargs and the ‘…’ argument
  24. Getting the array length of a 2D array in Java
  25. Reversing an Array in Java [duplicate]
  26. Java array, NullPointerException?
  27. How to calculate the median of an array?
  28. Java OutOfMemoryError in reading a large text file
  29. Why does printing a Java array show a memory location [duplicate]
  30. Finding the median value of an array?

Leave a Comment