Created
December 4, 2017 18:07
-
-
Save sergchil/2980743f1bdca72aec0b2f3ac8173b90 to your computer and use it in GitHub Desktop.
Flatten nested arrays
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
public static void main() { | |
Object[] array1 = new Object[]{3}; // [3] | |
Object[] array2 = new Object[]{1, 2, array1}; // [ 1, 2, [3] ] | |
Object[] nestedArrays = new Object[]{array2, 4, null}; // [ [ 1, 2, [3] ] 4 ] | |
ArrayList<Integer> flatOutput = new ArrayList<>(); | |
try { | |
flatten(nestedArrays, flatOutput); | |
System.out.println("flatOutput = " + flatOutput); | |
} catch (NullPointerException e) { | |
System.err.println("something goes wrong"); | |
e.printStackTrace(); | |
} | |
} | |
public void flatten(Object[] nestedArrays, ArrayList<Integer> flatOutput) throws NullPointerException { | |
if (nestedArrays == null) { | |
throw new NullPointerException("Input array should not be null"); | |
} | |
if (flatOutput == null) { | |
throw new NullPointerException("Output array should not be null"); | |
} | |
for (Object element : nestedArrays) { | |
// of course int is not derived from Object, int this case JVM uses autoboxing to store int as Integer | |
if (element instanceof Integer) { | |
// is number | |
flatOutput.add((int) element); | |
} else { | |
// is array | |
flatten((Object[]) element, flatOutput); | |
} | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment